Section 1 -

Seminomatous Germ Cell Tumors Jae Y. Ro Department of Pathology, Weill Medical School, Cornell University The Methodist Hospital Houston, TX

Testicular neoplasms constitute approximately 1% of all cancers in males. The American Cancer Society has estimated that in the year 2006, 8,250 patients will developed testicular cancer, and 370 of these will die of their disease. [1]Tumors of germ cell origin account for 94–96% of all testicular neoplasms, and those of sex cord-stromal origin constitute 4–6%. The remaining testicular neoplasms of diverse histologic derivations are rare, and account for approximately 1% of all testicular neoplasms. Table 1 lists the classification of testicular and paratesticular tumors and tumor-like lesions as published in the recent WHO book. [2] The pathologist plays a key role in the management of patients with testicular tumors by accurately classifying the tumor, by providing the appropriate pathologic stage (Table 2), and by identifying prognostic parameters, which may be useful in making the decision between surveillance and further treatment. Therefore, evaluation of a testicular tumor must include a careful gross examination to document tumor size, to determine if the tumor extends into the spermatic cord and tunica, to note the presence of variations in gross appearance including necrosis and hemorrhage, and to direct adequate sampling for microscopic examination (in general, one section per 1cm tumor diameter including areas with differing appearances). Microscopic examination must identify the histologic type (i.e. germ cell or non-germ cell tumor, seminoma or non-seminomatous or mixed germ cell tumors including the different components and their relative percentages), determine the involvement of the spermatic cord and tunica albuginea, and confirm the presence or absence of vascular or lymphatic invasion. Other features that may be included in the report are tumor necrosis, mitoses, fibrosis, syncytiotrophoblastic giant cells, lymphoplasmacytic infiltrate, a granulomatous reaction, and the status of background testis including intratubular germ cell neoplasia. [3] Germ Cell Neoplasms The diverse views on the histogenesis of germ cell neoplasms and the wide range of their histologic appearances are reflected in various classifications that have been proposed (Table 3). [2, 4] For the purposes of treatment, however, the tumors are conventionally divided into two major categories: seminoma and non-seminomatous germ cell tumor. [3] If the tumor is non-seminomatous, it must be further classified as a pure or a mixed tumor. For mixed germ cell tumors, all components present in the tumor should be reported along with the approximate volume of each. Tumors containing both seminomatous and non-seminomatous elements are regarded as non-seminomatous germ cell tumors for treatment purposes. [3] Intratubular Germ Cell Neoplasia Intratubular germ cell neoplasia (ITGCN) is widely believed to be the precursor of most invasive germ cell tumors. Although Wilms [5] in 1896 described the presence of atypical intratubular cells adjacent to an invasive carcinoma, it was Skakkebaek [6] who, in 1972, first reported that the atypical germ cells within the seminiferous tubules actually represented the precursor of the invasive testicular germ cell neoplasm. This in-situ phase of germ cell tumor occurs in 0.5–1% of infertile patients with severe oligospermia, 2–8% of those with cryptorchidism, and 5% of patients with a history of testicular cancer. [7] There is a 15–20% risk for development of ITGCN in the remaining (contralateral) testis in patients with a history of undescended testis and testicular carcinoma. [8] Patients with dysgenetic gonads and testicular feminization syndrome also have an increased incidence of ITGCN. [9] Approximately 50% of patients with ITGCN will progress to invasive carcinoma within 5 years, and 90% or more if orchiectomy is not performed. [7] Most patients with ITGCN develop seminoma, and, in fact, the terms seminoma in-situ and carcinoma in situ (or gonocytoma in-situ) have been used interchangeably for ITGCN. The term seminoma in-situ is considered unsuitable because seminiferous tubules are not entirely replaced by atypical cells, and follow-up studies have shown that even non-seminomatous tumors may develop if orchiectomy is not performed. The term carcinoma in-situ is not recommended either, because germ cells are not epithelial and their malignant potential has not been well established in all cases. Nevertheless, it is recognized that the presentation and behavior of this lesion is that of a preinvasive process clearly analogous to carcinoma in- situ in other sites. [7, 10] Pathologic features On gross examination there are no abnormal findings produced by the ITGCN other than conditions that may harbor it. Microscopically, the seminiferous tubules show decreased diameters and thickened tubular walls. In the early stages there are scattered large atypical cells (twice the size of normal germ cells) with prominent nucleoli and abundant clear cytoplasm situated between other cells exhibiting an apparently normal maturation sequence. In the later stages, the atypical cells frequently align themselves circumferentially along the basement membrane, and as the process progresses, the number of abnormal cells increase to the point of packing entirely the seminiferous tubule. High-magnification microscopy demonstrates large prominent cells imparting a "pagetoid" appearance; these cells display large nuclei with a coarse chromatin pattern and large, prominent and irregular nucleoli. Mitotic figures, including abnormal forms, are present, and there is abundant clear cytoplasm, that contains lipids and glycogen. The atypical germ cells have the ultrastructural characteristics of spermatogenic precursor cells or malignant seminomatous cells. The DNA content of these cells demonstrates an aneuploid pattern. Periodic acid–Schiff (PAS) stains, with and without diastase, show abundant glycogen in the cytoplasm. Immunohistochemistry Placental alkaline phosphatase (PLAP) is the most utilized diagnostic antibody, but other markers including CD117 (C-Kit), p53, neuron-specific enolase (NSE), ferritin, monoclonal antibody M2A (D2-40), OCT4 and 43-9F are positive in the atypical intratubular germ cells. Giwercman et al. [11] reported that the cells of ITGCN reacted with 43-9F antibody, whereas normal germ cells, Sertoli cells, Leydig cells, and endothelial cells did not. The loss of FHIT expression (FHIT gene, located at human chromosome 3p14.2) is a consistent characteristic of ITGCN, which suggests a potential role in a maturation/differentiation defect early in the development of testicular germ cell tumors. Likewise, the lack of its expression in seminomas is supportive of this view. However, re-expression of FHIT in well-differentiated glandular epithelium of teratomatous component of mixed germ cell tumors suggests that there is no loss of FHIT gene in this subset of neoplasia but rather that FHIT protein expression is differently regulated through the phases of germ cell tumor progression. [12] Cytokeratin, a -fetoprotein (AFP), and human chorionic gonadotrophin (hCG) are usually negative. However, intratubular embryonal carcinoma is immunoreactive for CD30, cytokeratin (AE1/AE3), cytokeratin 7 focally, and p53, but negative for cytokeratin 20, p21, and alpha-fetoprotein. Karyotypic analyses have demonstrated the common occurrence of a marker chromosome, is chromosome (12p), in ITGCN and seminomatous and non-seminomatous germ cell tumors. [13] RNA binding motif (RBM) protein is a novel marker consistently expressed in normal male germ cells but not in malignant germ cell tumors or ITGCN. Thus, the absence of RBM expression in germ cells provides a new diagnostic tool of preinvasive malignancy of the testis. [14] In 75–99% of cases, ITGCN is seen in tubules adjacent to invasive germ cell tumors; it is associated more frequently with non-seminomatous germ cell tumors than with seminomas. In most cases, the intratubular neoplastic cells lack evidence of further differentiation; therefore, specific histologic subtypes can only be determined after extra tubular extension occurs. Whether all invasive germ cell tumors develop from an intratubular phase or some develop de novo remains to be determined, but the frequent finding of abnormal germ cells in the tubules adjacent to invasive lesions suggests that the former is more likely. Commonly seen intratubular neoplasms include intratubular seminoma and intratubular embryonal carcinoma; other forms include intratubular spermatocytic seminoma and, rarely, intratubular forms of yolk sac tumors or trophoblastic neoplasia. Direct evidence that ITGCN is a precursor of pediatric yolk sac tumors and teratoma, and of the adult spermatocytic seminoma is lacking. However, recent reports have described ITGCN in children and adolescents. [15] Management There is controversy as to whether ITGCN should be treated. Some investigators advocate low dose radiation, while others advocate surveillance on the basis that if a new primary develops, it would be easy to detect by patient's self-examination, physical examination or by elevation of markers. Furthermore, if a tumor develops, modern management is very effective. Seminomatous Tumors There are two types of seminoma: classic seminoma and spermatocytic type. Classic Seminoma Seminoma is the most common testicular neoplasm and comprises 40–50% of all testicular germ cell tumors; [16] 85–90% of seminomas are of the "typical" or classic type, and the remainder consist of rare variants such as anaplastic seminoma, and seminoma with syncytiotrophoblastic giant cells. Seminoma is the most frequent germ cell tumor in patients with bilateral germ cell tumors (2%) and frequently occurs in undescended testes (5–8%). [17] Clinical presentation Seminoma occurs most commonly in patients 35 to 45 years old, is relatively uncommon in men over 50 years of age, and is rare in children. This age group is a decade higher than that of patients with non-seminomatous tumors. The clinical presentation includes testicular enlargement, with or without pain, in more than 70% of all affected patients, and 10% present with symptoms of metastases. Some patients with seminoma are asymptomatic. Gynecomastia, exophthalmos, and infertility are rare presenting symptoms. Elevated serum PLAP and hCG are seen in 40% and 10% of the patients respectively; the latter is the cause of gynecomastia. Approximately 75% of seminomas are confined to the testis at the time of presentation (extension to the spermatic cord or epididymis is seen in 5–8%); in contrast 50–70% of non-seminomatous germ cell tumors are metastatic by the time they are diagnosed. Pathologic features On gross examination, the tumor is a usually well-demarcated, homogeneous, firm mass, frequently white-gray, coarsely lobulated, and bulging. Hemorrhage and necrosis are uncommon but may be seen in large tumors. The tumors average 5cm, with rare cases exceeding 10cm; in a series of stage I seminomas, 61% measured 2–6cm. [18] Microscopic examination shows a diffuse proliferation of large cells arranged in sheets, nests, or cords. Tubular, reticular, cystic, and cribriform patterns have also been reported; the descriptive term tubular seminoma has been used for such pseudoglandular variations. [19] Areas of typical seminoma are always present in tumors with such variations. Usually seminoma destroys seminiferous tubules as it grows, but seminiferous tubules may be found entrapped between the tumor cells, at the periphery of the mass. The tumor cells are evenly spaced and are relatively large but uniform and have a distinct cell membrane. They contain a centrally located, large, round nucleus which has a sharp nuclear membrane, traversed by thin bands of chromatin, with one or two prominent nucleoli. The cytoplasm is abundant and usually clear, but may be eosinophilic or amphophilic. Mitotic figures are common. Discrete (50–60% cases) or diffuse granulomatous reaction with or without multinucleate giant cells occurs in seminoma. In metastatic disease, the granulomatous inflammation may predominate making diagnosis extremely difficult. Immunohistochemistry with PLAP, D2-40 and OCT4 is very helpful in this situation. [20] Scattered syncytiotrophoblastic giant cells are present in 10–20% of cases. Other forms of giant cells that may be present in seminoma include mulberry cells and the previously mentioned Langhans giant cells associated with granulomata. Extensive calcification and ossification may occur in seminoma (ossifying seminoma). The tumor is separated into lobules by a supporting stroma, which contains a variable number of lymphocytes. The extent of lymphocytic infiltration (predominantly T lymphocytes) varies from tumor to tumor as well as within different parts of the same tumor. The stroma also varies in amount from scanty to abundant, and varies in appearance from a fine fibrovascular network to large fibrous bands or septa, which may be hyalinized. In some tumors the amount of connective tissue may be abundant to such extent that the cells are difficult to discern. In rare instances, the seminoma cells are no longer present, but the whole tumor is replaced by a mass of hyalinized fibrotic, occasionally calcified tissue, which in the proper circumstances would suggest a burnt-out seminoma. The presence of ITGCN strongly supports the diagnosis of burnt-out seminoma. The pattern of seminoma cells involving rete testis epithelium is indistinguishable from the pattern of ITGCN. When pagetoid involvement of the rete testis occurs, the resulting tubulo-glandular architecture may be confused with embryonal carcinoma. This pagetoid extension has no prognostic significance. Seminomas may infarct completely resulting in a mass containing "ghost" cells suspicious for neoplasm. When architectural distortion is present in a neoplasm suspicious for seminoma, special stains may help. Florentine et al [21] reported that a Masson trichrome stain greatly improved nuclear and cytologic detail, confirming the suspicion of neoplasm. Placental alkaline phosphatase revealed specific membrane staining of the neoplastic cells and established a diagnosis of seminoma. Thus, Masson-trichrome stain plus selected immunostains offer a promising approach to the diagnosis of certain necrotic neoplasms. The controversial anaplastic variant constitutes 5–15% of seminomas. There is no gross difference between the anaplastic seminoma and the classic seminoma. On microscopic examination, anaplastic seminoma is characterized by increased mitotic activity (3 or more mitoses per 1 high-power field) and nuclear pleomorphism. Kademian et al. [22] reporting on 8 cases of anaplastic seminoma, concluded that this variant is more aggressive than classic seminoma, even when the two are compared stage by stage; Bobba et al. [23] reported similar results, stating that there was a difference in survival and relapse rate between classic and anaplastic seminomas. Other authors, however, have contended that, although the overall survival rate of patients with anaplastic seminoma is lower than that recorded for patients with classic seminoma, this difference disappears when the equivalent stages are compared. A higher percentage of anaplastic seminomas have already metastasized at presentation in contrast to classic seminomas that are usually confined to the testis. This undoubtedly contributes to the lower overall survival rate for patients with anaplastic seminoma. [24] Histochemistry and immunohistochenistry Staining by PAS with and without diastase demonstrates glycogen in the cytoplasm of the tumor cells. Immunostaining for PLAP, D2-40 and NSE is diffusely positive in these cells. OCT4 (POU5F1) is a transcription factor expressed in embryonic stem and germ cells and is positive in seminoma cell nuclei. [20] Vimentin can be positive, but EMA, AFP, and Ki-1 (Ber-H2; CD 30) are negative in most seminomas. Cytokeratin may be focally positive in up to 40% of the tumor cells. The syncytiotrophoblastic giant cells are positive with cytokeratin and hCG, findings that should not be misinterpreted as indicating carcinomatous differentiation. A recent study demonstrated that a somatic isoform of angiotensin I-converting enzyme (CD143) is an appropriate marker for seminomatous differentiated tumors since spermatocytic seminoma and nonseminomatous germ cell tumors are negative for this marker. [25] hCG and a-fetoprotein in seminoma Between 5% and 60% of patients with pure seminoma have mildly elevated serum levels of hCG because of the syncytiotrophoblastic giant cells, but these normalize after orchiectomy. An elevated hCG level does not appear to have an adverse effect on the prognosis of patients. Persistently elevated levels of hCG following orchiectomy indicate a hidden focus of choriocarcinoma. An elevated serum AFP level virtually excludes a diagnosis of pure seminoma, even though microscopic evaluation may show only the seminomatous component without evidence of any other non-seminomatous germ cell elements; these patients should be treated on a non-seminoma protocol. However, minor elevations of serum AFP (<16ng/ml) may be acceptable. [26] The differences in management between seminoma and non-seminomatous tumors and the potentially focal nature of the non-seminomatous component make it imperative that multiple tumor sections be examined before the tumor is diagnosed as a seminoma. Another marker that may be useful in monitoring patients with seminoma is the serum level of NSE. Increased serum NSE was found in 8 of 11 patients (73%) with metastatic seminoma, whereas serum NSE level was normal in 53 of 54 seminoma patients with no evidence of metastasis. Furthermore, serum NSE level returns to normal following chemotherapy. Based on these findings, Kuzmits et al. [27] reported that NSE measurement is clinically valuable for monitoring the results of chemotherapy in patients with metastatic seminoma. Cytogenetic findings The most common structural cytogenetic abnormality in seminoma is the presence of isochromosome 12p. Some patients lack the isochromosome 12p but have other structural chromosomal abnormalities. Hiwi maps the long arm of chromosome 12, band 12q24.33, a genomic region that displays genetic linkage to the development of testicular germ cell tumors, seminomas and nonseminomas, in adolescents and adults. [28] In normal human testes, hiwi is specifically expressed in germline cells, with its expression detectable in spermatocytes and round spermatids during spermatogenesis. No expression was observed in testicular tumors of somatic origin, such as Sertoli cell and Leydig cell tumors. Qiao et al [28] reported that enhanced expression was found in 12 of 19 sampled testicular seminomatous tumors, but no enhanced expression was detected in 10 nonseminomatous testicular tumors that originated from the same precursor cells as seminomas yet had lost their germ cell characteristics. Finally, no enhanced expression was detected in four spermatocytic seminomatous tumors. Loss of growth hormone variant (GH-V) gene expression in testicular GCTs compared with normal testis and loss (seminoma) or mutation (NSGCT) of placental lactogen-like (PLL) gene products might have significance in terms of the relationship between these tumors and for testicular GCT development. [29] A recent study reported that MAGE-1 antigen (member of the melanoma antigen-encoding gene family) was identified in 16.6% of seminomas. No embryonal carcinomas, yolk sac tumors, or teratomas contained MAGE-1 protein. MAGE-3 antigen was identified in 41.8% of seminomas, and this protein was not identified in embryonal carcinomas, yolk sac tumors, or teratoma. In seminoma, the presence of MAGE-1 and MAGE-3 antigens did not correlate with tumor size, tumor stage, the presence of a lymphoid infiltrate, or patient outcome. The low frequency of MAGE-specific HLA alleles in the population, the loss of the HLA class I antigens in neoplastic germ cells, and the finding that the majority of seminomas and all non-seminomatous germ cell tumors lacked MAGE-1 and MAGE-3 antigenic peptides indicate that immunotherapy directed towards MAGE-1 and MAGE-3 antigen is not a likely treatment option for seminoma and nonseminomatous germ cell tumors. [30] Zeeman et al [31] detected VASA mRNA (by quantitative RT-PCR) and protein (by immunohistochemical staining) in normal spermatogenesis, seminoma (both classic and spermatocytic), carcinoma in situ (the precursor of classic seminoma and nonseminoma), dysgerminoma, and gonadoblastoma. Differential diagnosis The main differential diagnosis includes malignant lymphoma, embryonal carcinoma, and endodermal sinus tumor. Other lesions may also enter in the differential diagnosis and these include choriocarcinoma, granulomatous orchitis, Sertoli cell tumor, and spermatocytic seminoma. Large cell lymphoma, either primary or metastatic is relatively easy to rule out. Characteristically, large cell lymphoma show interstitial infiltration of tumor cells between the seminiferous tubules. There is absence of a malignant intratubular germ cell proliferation and usually there is no fibrosis or granulomatous reaction. Lymphoma more frequently involves the tunica, epididymis, and spermatic cord than does seminoma. PLAP, OCT4, D2-40, CD20, CD3, and leukocyte common antigen (LCA) immunostains are helpful. Embryonal carcinoma is usually seen in the third decade of life; it shows greater cellular and nuclear pleomorphism and more brisk mitotic activity than seminoma. It may also show areas of papillary and pseudoglandular patterns and a syncytial arrangement of the cells. Embryonal carcinoma is positive for cytokeratin and Ki-1 (CD 30) antigen, in contrast to seminomas. Pure endodermal sinus tumor is usually seen in children and is more likely to be arranged in reticular, myxoid, and microcystic patterns. The deposit of basement membrane-like material between tumor cells (parietal yolk sac differentiation) is a characteristic feature. Cytokeratin and AFP immunostaining are helpful in differentiating this tumor from seminoma. Spermatocytic seminoma occurs in patients over 50 years of age and generally consists of round cells with marked polymorphism due to the presence of three cell types, including the very characteristic giant cells. It is usually not associated with fibrovascular septa, lymphocytic infiltration, or granulomatous reaction. Seminomas with numerous syncytiotrophoblastic giant cells differ from choriocarcinoma in that the former lack the typical biphasic appearance, abortive villous architecture, and tumor necrosis and hemorrhage. A marked granulomatous reaction in seminoma, which masks neoplastic cells, may mimic granulomatous orchitis. The presence of ITGCN at the periphery of the lesion, a careful search under high-power examination for tumor cells, and immunostains for PLAP are helpful to resolve the diagnostic difficulty. Finally, the tubular and pseudoglandular architecture in seminomas ("tubular seminoma") and pagetoid spread into the rete testis may mimic Sertoli cell tumor. The former is invariably associated with more typical areas of classic seminoma. PLAP immunostaining is also helpful as it is negative in Sertoli cell tumors. Management of seminoma Management of patients with classic seminoma depends largely on the stage of the disease. Stage I disease (localized tumor to testis without metastasis) may be treated with a surveillance protocol or with radiotherapy after radical orchiectomy. The recommended treatment after orchiectomy is low dose radiotherapy, which would cure 99% of the cases. Pathologic parameters including intensity of lymphoplasmacytic infiltrations, the degree of granulomatous reaction, tumor necrosis, fibrosis, invasion, and interstitial cell hyperplasia, do not correlate with survival. Therefore, this tumor's characteristics are not of clinical significance when low dose radiotherapy is utilized for stage I classic seminoma. Although vascular-lymphatic invasion does have an impact on prognosis, its presence makes the patient ineligible for "surveillance-only" protocols. [32] In surveillance protocols, studies have shown that the size of the primary tumor and invasion of the rete testis are independent prognostic factors. Lesions less than 3cm, 3 to 6 cm and larger than 6cm have shown relapse free survivals rates of 94%, 82%, 64% respectively at 4 years. A tumor size greater than 6.0cm has been correlated with a higher rate of relapse. [33] Therefore, for surveillance protocols, these factors are very important. Stage II disease is generally treated according to the size of the lesion, low volume (<5cm) or high volume disease (>6 in the retroperitoneum). The former receive radiotherapy, while larger lesions receive chemotherapy. Stage III disease is treated with chemotherapy. The most important prognostic factor for seminoma is the clinical stage at presentation. Five-year survival rates according to stage of disease are 99%, 89% and 70–85% for stages I, II and III, respectively. Spermatocytic Seminoma Spermatocytic seminoma is an uncommon tumor comprising 3–7% of all seminomas. Masson first described it as a separate histologic variant of seminoma in 1946. [34] He postulated that the classic seminoma originated from undifferentiated germ cells and that spermatocytic seminoma was derived from cells undergoing spermatogenesis and hence represented a more differentiated type of germ cell neoplasm. Proteins which are highly expressed in spermatocytes and spermatogonia, such as Chk2, MAGE-A4, neuron-specific enolase, SSX and NY-ESO-1 are also expressed in spermatocytic seminoma, but p19INK4d which may be associated with the transition from mitotic to meiotic cell cycle are not expressed. Based on these results it has been proposed that the pattern of expression is consistent with the origin of spermatocytic seminoma from a premeiotic germ cell, spermatogonia or primary spermatocytes of the adult testis, which has lost embryonic traits and has committed to spermatogenic lineage but has not yet passed the meiotic checkpoint. Clinical features Spermatocytic seminoma is a germ cell neoplasm unique to the testis and is almost always seen in pure form, although rare cases have been associated with sarcomatous dedifferentiation. [35] It is prevalent in men older than 50 years of age (median 55 years) who present with painless testicular enlargement, but rarely may occur at a much younger age, as young as 23 years. It has an indolent clinical behavior. Of over 150 reported cases there is only one bona fide case of a pure tumor with distant metastasis. In contrast, 5 of 9 cases of spermatocytic seminoma with sarcomatoid dedifferentiation have died of metastasis. This tumor is not associated with either cryptorchidism or ITGCN. It is more often bilateral (10%) than is classic seminoma (2%). Pathologic features The size of the tumors varies from 3 to 15cm. On gross examination they are yellow-gray, soft, and gelatinous, and form a well-circumscribed mass with cystic change and hemorrhage. They are yellowier, softer, and more mucoid than the classic seminomas. In cases with sarcomatous dedifferentiation the tumor may appear more solid and dull-gray. On low-magnification microscopy, spermatocytic seminoma shows a diffuse proliferation of polymorphic cells, usually of three types, with focal microcysts and intratubular and interstitial growth patterns. There is lack of a prominent fibrovascular stroma, and minimal or no lymphocytic infiltrate or granulomas are seen. The cytoplasm usually does not contain glycogen. No other germ cell components are associated with this tumor. On high magnification, there are three cell types, and each has distinctive morphology. The large cells (50–100mm) are the least common and are uninucleated or multinucleated. The cytoplasm of the tumor cells is abundant and eosinophilic. The tumor cells have uniform, round nuclei but vary markedly in size. The nuclei contain "spireme" chromatin similar to primary spermatocytes in meiotic prophase. The intermediate cells (10–20mm) have perfectly round nuclei with evenly dispersed granular chromatin or rarely spireme chromatin and eosinophilic cytoplasm. The small cells are lymphocyte-like (6–8mm) and have uniformly hyperchromatic nuclei and scant cytoplasm. The spireme character of the nucleus in the intermediate and large cells differentiates this tumor from the classic seminoma. Numerous mitoses may be evident. Although spermatocytic seminomas are not associated with other germ cell components, in about 6% of cases they are associated with a high-grade sarcoma such as fibrosarcoma, rhabdomyosarcoma, or undifferentiated sarcoma. True et al [36] proposed that this is an expression of anaplastic transformation of the spermatocytic seminoma, analogous to that seen in tumors in other organs. The presence of the sarcomatous elements transforms the usually innocuous spermatocytic seminoma into a highly aggressive neoplasm. In 5 of 9 reported patients with sarcomatous transformation who died of metastatic disease, death occurred within 2 years after orchiectomy, and only the sarcomatous elements metastasized. This type of spermatocytic seminoma is reported to be resistant to chemotherapy. An "anaplastic" variant of spermatocytic seminoma has recently been described; it is characterized by a marked predominance of monomorphous cells with prominent nucleoli, which may be potentially mistaken for an embryonal carcinoma or seminoma. [37] There is no apparent prognostic significance to the diagnosis of "anaplastic" spermatocytic seminoma. Immunohistochemistry Various tumor markers, including the intermediate filaments, D2-40, OCT4 and PLAP that are demonstrated in other types of germ cell tumor, have not been detected in spermatocytic seminoma. Consistent expression of c-kit and VASA has been described in the spermatocytic seminoma. [38] Dot-like expression may be found with cytokeratin 18. Proteins highly expressed in gonocytes and spermatogonia, such as Chk2, MAGE-A4 and neuron-specific enolase, are consistently present in spermatocytic seminoma. Antigens expressed in embryonic germ cells but not in the normal adult testis, e.g. TRA-1-60, are undetectable, with the exception of p53 protein, which is demonstrated in 80% of cases. A proto-oncogene p19INK4d, which is involved in the transition from mitotic to meiotic division in germ cells, is not detected in spermatocytic seminoma. The pattern of expression is highly consistent with the origin of spermatocytic seminoma from a premeiotic germ cell, which has lost embryonic traits and has committed to spermatogenic lineage but has not yet passed the meiotic checkpoint, most probably from the spermatogonium of the adult testis. The NY-ESO-1 gene is the most recently identified member of the cancer/testis family and its product is one of the most immunogenic tumor antigens. Satie et al [39] reported that NY-ESO-1 was not expressed in the Sertoli cells, Leydig cells, classical seminomas, or nonseminomatous germ cells in the 59 testicular tumors. In contrast, NY-ESO-1 was expressed both in carcinomas in situ, which are the earliest stage of testicular tumors (7 of 15 cases), and in spermatocytic seminomas, which are believed to be derived from spermatogonia or primary spermatocytes (8 of 16 cases). NY-ESO-1 is a marker that can be used to follow the early progression of testicular tumorigenesis when the tumors present a similar pattern of expression to the cells from which they originated, although the later tumors cease to express NY-ESO-1. Differential diagnosis The differential diagnosis of spermatocytic seminoma includes classic seminoma, malignant lymphoma, and solid embryonal carcinoma. In classic seminoma, tumor cells are large and are of only one type, with abundant clear or eosinophilic cytoplasm; the nuclei are more vesicular and have one or two prominent nucleoli. The tumor cells are evenly spaced with distinct cell borders, and fibrovascular septa divide the tumor cells into lobules, imparting a mosaic appearance. There is an associated lymphoplasmacytic infiltration and granulomatous response in the stroma and uninvolved seminiferous tubules. Malignant lymphoma is characterized by a higher frequency of bilaterality. The large cell lymphoma consists of oval to round lymphoid cells with cellular and nuclear pleomorphism, and the growth pattern is predominantly interstitial with destruction of seminiferous tubules. Leukocyte common antigen staining is very useful. Embryonal carcinoma is usually seen in the third decade of life. This tumor showing more nuclear pleomorphism than spermatocytic seminoma, has a brisker mitotic rate and syncytial arrangement of tumor cells. It usually displays other growth patterns, including papillary, solid, and pseudoglandular components. Management Radical orchiectomy is the treatment of choice and there is no role for retroperitoneal lymphadenectomy. Most patients receive low dose radiation to the lower abdomen, but the utility of postoperative radiation remains uncertain and needs to be addressed with a randomized study in the future. [40] Table 1: WHO histological classification of testis tumors Germ cell tumors Intratubular germ cell neoplasia, unclassified 9064/2 [1] Other types Tumors of one histological type (pure forms) Seminoma 9061/3 Seminoma with syncytiotrophoblastic cells Spermatocytic seminoma 9063/3 Spermatocytic seminoma with sarcoma Embryonal carcinoma 9070/3 Yolk sac tumors 9071/3 Trophoblastic tumors Choriocarcinoma 9100/3 Trophoblastic neoplasms other than choriocarcinoma Monophasic choriocarcinoma Placental site trophoblastic tumors 9104/1 Teratoma 9080/3 Dermoid cyst 9084/0 Monodermal teratoma Teratoma with somatic type malignancies 9084/3 Tumors of more than one histological type (mixed forms) Mixed embryonal carcinoma and teratoma 9081/3 Mixed teratoma and seminoma 9085/3 Choriocarcinoma and teratoma/embryonal carcinoma 9101/3 Others Sex cord/gonadal stromal tumors Pure forms Leydig cell tumors 8650/1 Malignant Leydig cell tumor 8650/3 Sertoli cell tumors 8640/1 Sertoli cell tumor lipid rich variant 8641/0 Sclerosing Sertoli cell tumor Large cell calcifying Sertoli cell tumor 8642/1 Malignant Sertoli cell tumor 8640/3 Granulosa cell tumor 8620/1 Adult type granulose cell tumor 8620/1 Juvenile type granulose cell tumor 8622/1 Tumors of the thecoma/fibroma group Thecoma 8600/0 Fibroma 8810/0 Sex cord/gonadal stromal tumors: Incompletely differentiated 8591/1 Sex cord/gonadal stromal tumors, mixed forms 8592/1 Malignant sex cord/gonadal stromal tumors 8590/3 Tumors containing both germ cell and sex cord/gonadal stromal elements Gonadoblastoma 9073/1 Germ cell-sex cord/gonadal stromal tumor, unclassified Miscellaneous tumors of testis Carcinoid tumor 8240/3 Tumors of ovarian epithelial types Serous tumor of borderline malignancy 8442/1 Serous carcinoma 8441/3 Well differentiated endometrioid ca 8380/3 Mucinous cystadenoma 8470/0 Mucinous cystadenocarcinoma 8470/3 Brenner tumor 9000/0 Nephroblastoma 8960/3 Paraganglioma 8680/1 Hematopoietic tumors Tumors of collecting ducts and rete Adenoma 8140/0 Carcinoma 8140/3 Tumors of paratesticular structures Adenomatoid tumor 9054/0 Malignant mesothelioma 9050/3 Benign mesothelioma Well differentiated papillary mesothelioma 9052/0 Cystic mesothelioma 9055/0 Adenocarcinoma of epididymis 8140/3 Papillary cystadenoma of epididymis 8450/0 Melanotic neuroectodermal tumor 9363/0 Desmoplastic small round cell tumor 8806/3 Mesenchymal tumors of spermatic cord and testicular adnexa Secondary tumors of testis Table 2: TNM classification of germ cell tumors of the testis TNM classification [1, 2] T - Primary tumor Except for pTis and pT4, where radical orchiectomy is not always necessary for classification purposes, the extent of the primary tumor is classified after radical orchiectomy; see pT. In other circumstances, TX is used if no radical orchiectomy has been performed N - Regional lymph nodes NX Regional lymph nodes cannot be assessed N0 No regional lymph node metastasis N1 Metastasis with a lymph node mass 2cm or less in greatest dimension or multiple lymph nodes, none more than 2cm in greatest dimension N2 Metastasis with a lymph node mass more than 2cm but not more than 5cm in greatest dimension, or multiple lymph nodes, any one mass more than 2cm but not more than 5cm in greatest dimension N3 Metastasis with a lymph node mass more than 5cm in greatest dimension M - distant metastasis MX Distant metastasis cannot be assessed M0 No distant metastasis M1 Distant metastasis M1a Non regional lymph node(s) or lung M1b Other sites pTNM pathological classification pPT - Primary tumor PTX Primary tumor cannot be assessed (See T-primary tumor, above) pT0 No evidence of primary tumor (e.g. histologic scar in testis) pTis Intratubular germ cell neoplasia (carcinoma in situ) pT1 Tumor limited to testis and epididymis without vascular/lymphatic invasion; tumor may invade tunica albuginea but not tunica vaginalis pT2 Tumor limited to testis and epididymis with vascular/lymphatic invasion, or tumor extending through tunica albuginea with involvement of tunica vaginalis pT3 Tumor invades spermatic cord with or without vascular/lymphatic invasion pT4 Tumor invades scrotum with or without vascular/lymphatic invasion pN - regional lymph nodes PNX Regional lymph nodes cannot be assessed pN0 No regional lymph node metastasis pN1 Metastasis with a lymph node mass 2cm or less in greatest dimension and 5 or fewer positive nodes, none more than 2cm in greatest dimension pN2 Metastasis with a lymph node mass more than 2cm but not more than 5cm in greatest dimension; or more than 5 nodes positive, none more than 5cm; or evidence of extranodal extension of tumor pN3 Metastasis with a lymph node mass more than 5cm in greatest dimension S - Serum tumor markers SX Serum marker studies not available or not performed S0 Serum marker study levels within normal limits LDH hCG(mlU/ml) AFP S1 <1.5 x N and <5,000 And <1,000 S2 1.5-10 x N or 5,000-50,000 or 1,000-10,000 S3 >10 x N or >50,000 or >10,000 N indicates the upper limit of normal for the LDH assay Stage grouping Stage 0 pTis N0 M0 S0, SX Stage I pT1-4 N0 M0 SX Stage IA pT1 N0 M0 S0 Stage IB pT2 N0 M0 S0 pT3 N0 M0 S0 pT4 N0 M0 S0 Stage IS Any pT/TX N0 M0 S1-3 Stage II Any pT/TX N1-3 M0 SX Stage IIA Any pT/TX N1 M0 S0 Any pT/TX N1 M0 S1 Stage IIB Any pT/TX N2 M0 S0 Any pT/TX N2 M0 S1 Stage IIC Any pT/TX N3 M0 S0 Any pT/TX N3 M0 S1 Stage III Any pT/TX Any N M1, M1a SX Stage IIIA Any pT/TX Any N M1, M1a S0 Any pT/TX Any N M1, M1a S1 Stage IIIB Any pT/TX N1-3 M0 S2 Any pT/TX Any N M1, M1a S2 Stage IIIC Any pT/TX N1-3 M0 S3 Any pT/TX Any N M1, M1a S3 Any pT/TX Any N M1b Any s Table 3: Comparison of various classifications of testicular germ cell tumors AFIP (1999) WHO (1977) Dixon &Moore (1952) Mostofi (1980) British Testicular Tumor Panel (Pugh 1976) Seminoma Seminoma Group I seminoma Seminoma Seminoma Spermatocytic seminoma Spermatocytic seminoma Not listed Spermatocytic seminoma Spermatocytic seminoma Embryonal carcinoma Embryonal carcinoma Group II Embryonal carcinoma embryonal carcinoma adult-type Malignant teratoma undifferentiated Yolk sac tumor Yolk sac tumor (endodermal sinus tumor) Not listed Infantile embryonal carcinoma Yolk sac tumor in children (orchioblastoma) Polyembryoma Polyembryoma Not listed Polyembryoma Not listed Choriocarcinoma Placental site trophoblastic tumor Choriocarcinoma pure Group V Choriocarcinoma choriocarcinoma, pure Malignant teratoma, trophoblastic Teratoma: mature immature monodermal Teratoma: mature immature Group III teratoma pure ± seminoma Teratoma: mature immature Teratoma, differentiated Teratoma with secondary malignant component(specify) Teratoma with malignant transformation Group IV teratoma, with EC and/or C ± seminoma Teratoma with malignant areas other than S, EC, C Malignant teratoma, intermediate Mixed germ cell tumor (specify components) Embryonal carcinoma and teratoma (teratocarcinoma) Choriocarcinoma and other type Other combinations Group IV teratoma with EC and/or C + seminoma Group V choriocarcinoma with S and/or EC Not listed Embryonal carcinoma and teratoma (teratocarcinoma) Specify tumor type Specify tumor type Malignant teratoma, intermediate Malignant teratoma trophoblastic Combination tumors References Jemal A, Siegal R, Ward E, et al. 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