Small blue cells in a postmenopausal Pap test Dr. Máire Duggan

Clinical History A 69 year old woman had a routine Pap test. Past history, systems review and physical examination were unremarkable. She was seen in colposcopy and had a cervical biopsy. This showed postmenopausal squamous atypia. The acanthotic squamous epithelium had an endophytic growth pattern. Small basal cells with enlarged hyperchromatic round nuclei formed grape like clusters and pseudoglandular spaces in the endophytic areas. Slide 1 Click to view with ImageScope Click to view with a Web-Based Viewer Diagnosis: Small blue cells in a postmenopausal Pap test. Discussion The postmenopausal cervico-vaginal smear has a unique cytology due to the hypo-estrogenic state [1]. Somewhat similar changes may occur in smears of women who are post partum or lactating, using exogenous progesterone, or who have been iatrogenically castrated or have premature ovarian failure. The hormonal hypo-estrogenism results in an atrophic squamous epithelium that is susceptible to trauma and infection. The parabasal cell predominates and in smear preparations is present singly or in overlapping, syncytial groups. Other cells include parkeratotic cells, histiocytes and red blood cells, and in the case of atrophic vaginitis, an exudate composed of acute and chronic inflammatory cells and cell debris. Cell abnormalities in the post menopausal smear due to estrogen deficiency occur and can lead to false positive reporting of ASC-US (atypical squamous cells of undetermined significance), ASC-H (atypical squamous cells, cannot exclude high grade squamous intraepithelial lesion), AGC (atypical glandular cells), LSIL (low grade squamous intraepithelial lesion) HSIL (high grade squamous intraepithelial lesion) or malignant [1]. The likelihood is increased when the smear is compromised by inflammatory and degenerative changes. Enlargement of the parabasal nucleus is a common benign manifestation of estrogen deficiency [2]. In contrast to the definition of ASC-US in the premenopausal woman (nuclear size 2 to 3 times that of an intermediate cell nucleus), ASC-US in the postmenopausal woman is present when the parabasal nuclear size compared to an intermediate cell nucleus is 3 to 4 greater or there is more than mild nuclear hyperchromasia and nuclear membrane irregularity [2]. Other estrogen deficiency abnormalities are small blue cells, blue blobs, atypical parakeratosis, transitional cell metaplasia, and postmenopausal squamous atypia [1]. Small blue cells (SBCs) as demonstrated in the current case have little to no cytoplasm and the hyperchromatic nuclei occur in small grape like clusters and as single cells [3, 4]. Multiple clusters are more frequent than the occasional one. The nuclei are round, hyperchromatic and equal the size of an intermediate cell nucleus. Nucleoli are absent or minute. There is no molding, chromatin streaking, mitotic activity or tumor diathesis. While sometimes reported as atypical endometrial glandular cells, follow up has been negative for intraepithelial neoplasia and malignancy [3, 4]. Small blue cells are speculated to be the cytological counterpart of the reserve cell. The current case suggests it is the proliferating parabasal cell of postmenopausal squamous atypia. The small blue cell received increased attention in recent years co-incidental with the use of Tamoxifen in the management and prevention of breast cancer [3]. Tamoxifen is a nonsteroidal anti-estrogen, but paradoxically has an estrogenic effect in the female genital tract [5]. Initially 40% of smears of women on Tamoxifen were reported to have this abnormality [3]. A later case control study showed the frequency of small blue cells in post menopausal (>50 years) women regardless of whether they were on Tamoxifen or not was 21% [4]. In both the cases and controls, the frequency did correlate with advancing age and was highest in those over 70 years. Small blue cells were infrequently seen in the smears of women 50 years and younger. As expected, a background proliferative pattern was more frequent in the Tamoxifen treated group and contrasted with the control group in which the majority of the smears were atrophic. The differential diagnosis of small blue cells in a Pap test can be categorized as benign, premalignant and malignant. Amongst women treated for breast cancer with Tamoxifen, 36% developed endometrial pathology [6]. Benign endometrial polyp was the most frequent, but hyperplasia, carcinoma, carcinosarcoma or adenosarcoma have also been documented. Thus the differential diagnosis of small blue cells in Tamoxifen treated women will be slanted towards these endometrial lesions as well as metastatic breast carcinoma. The benign category of differential diagnoses includes benign endometrial glandular and/or stromal cells [3, 4]. Benign endometrial shedding in the postmenopausal woman may be physiologic or pathologic. Pathologic causes include endometrial polyp, endometrial hyperplasia, or a well differentiated, endometrioid carcinoma. Prolapsed fallopian tube and cervical endometriosis are other considerations. Benign endometrial glandular cells are usually in groups either as a strip, monolayered sheet or a group of overlapped crowded cells (HCG) [7]. When associated with stroma, endometrium may form exit balls and glandular strips with an attached layer of stromal cells. Exit balls are rounded structures with a smooth external layer of glandular cells and a central aggregation of stromal cells. Necrosis is absent and mitoses are infrequent. The glandular cells are cuboidal and have a small to moderate amount of pale cytoplasm, which may be vacuolated. The nuclei are round, uniform in size and shape, centralized or polarized towards the base of the cell and the nuclear chromatin is uniform and increased. Nucleoli are small or absent. Stromal cells are smaller with a large oval or spindle shaped hyperchromatic nucleus. The premalignant category includes HSIL, in particular the small cell type. In HSIL, individual cell necrosis may occur and the dysplastic cells have a variable amount of cytoplasm. The cells show more variability in nuclear size and shape, and the chromatin pattern is finely or coarsely granular. The nuclear membrane is irregular and there is mitotic activity. The malignant category includes such primary tumors as small cell squamous carcinoma, small cell neuroendocrine carcinoma, serous carcinoma, and adenoid cystic carcinoma [3, 4]. Secondary or metastatic tumors to consider include metastatic breast carcinoma in particular lobular carcinoma and metastatic small cell carcinoma from such sites as the lung and the gastrointestinal tract [3, 4]. Malignant lymphoma either primary or metastatic although rare is also a possibility [8]. A background tumor diathesis composed of blood and inflammation usually accompanies malignant neoplasms. Small cell squamous carcinoma cells have a small amount of cytoplasm and the nuclei are hyperchromatic, irregular, and mitotically active. Small cell neuroendocrine carcinoma cells show nuclear molding and if there is air drying artefact chromatin streaking may be present. Serous carcinoma cells form small 3 dimensional ball like aggregates resembling papillae. The nuclei show a severe degree of atypia and have nucleoli. Psammoma bodies may be present. Adenoid cystic carcinoma may show small tubular aggregates with colloid like material in the centre. Metastatic breast carcinoma, in particular lobular carcinoma may occasionally present as an abnormal Pap test. The cells of duct carcinoma are large and the enlarged nucleus has a large nucleolus. Lobular carcinoma cells may be plasmacytoid or have a signet ring shape. Malignant Non Hodgkins lymphoma may show cellular smears formed of small, intermediate or large cells. Mixed patterns may also occur. Small cell lymphoma is difficult to distinguish from a lymphocytic cervicitis. Tingible body macrophages are more compatible with a benign diagnosis. Intermediate and large cell lymphoma cells have large hyperchromatic nuclei with little cytoplasm. In some types, the nuclei may have irregular nuclear membranes, and nucleoli. Individual cell necrosis may also be seen. Knowledge of the patient age and hormonal status and drug history are critical to making a diagnosis of small blue cells in a post menopausal Pap test. HPV (Human Papilloma Virus) is infrequent in the post menopausal cervix and while HPV DNA (deoxyribonucleic acid) testing in the scenario of the small blue cell has not been investigated, a positive result might assist in stratifying those in need of colposcopic investigation [1, 9]. The value of p16 expression is unknown, but as a surrogate marker of high risk HPV in cervical specimens it may be a useful triage test. Blue blobs also termed cyanophilic bodies occur in approximately 20% of postmenopausal smears and most likely are degenerated parabasal cells [10]. They are large granular objects about the size of a parabasal cell. They contain a central degenerated nucleus that retracts from the cytoplasm imparting a lamellated appearance to the cell. Naked nuclei about the size and shape of a Trichomonad may also be seen. Atypical parakeratosis is a large cell with orangeophilic cytoplasm and an enlarged blue black, irregular nucleus that may be multinucleated. It is a reactive and likely protective process in the immature squamous epithelium. Both blue blobs and atypical parakeratosis can be worrisome for a carcinoma, but follow up biopsy studies have been negative for intraepithelial neoplasia and malignancy. The histology of transitional cell metaplasia because the immature epithelium can resemble HSIL is more worrisome than the smear presentation [11]. The smear is usually unremarkable, but may show sheets of streaming cells with elongated nuclei and nuclear grooves. SIL (squamous intraepithelial lesion) features of marked nuclear enlargement and hyperchromasia are absent. Postmenopausal squamous atypia has some features of LSIL both in smear and biopsy specimens [1, 9]. Cells with an increased nuclear cytoplasmic ratio and perinuclear halos occur. They lack the smudgy hyperchromasia and nuclear membrane irregularity of a true koilocyte, but the pseudokoilocyte may be reported as an ASC-US or LSIL. The atypia does not progress to malignancy and is negative for HPV DNA [9]. Blue blobs, atypical parakeratosis and small blue cells in a Pap test should be reported as negative for intraepithelial lesion and malignancy. A recommendation for topical estrogen therapy followed by a repeat Pap test is appropriate if the features are worrisome for SIL [1]. Most but not all hormone dependant atypias will reverse on this regimen. SIL and malignancy will persist and referral for colposcopic examination in that circumstance is appropriate. References Tambouret RH, Wilbur DC. The many faces of atrophy in gynaecologic cytology. Clin Lab Med. 2003; 23:659-79. Abati A, Jaffurs W, Wilder AM. Squamous atypia in the atrophic cervical vaginal smear: a new look at an old problem. Cancer. 1998; 84:200-1. Yang YJ, Trapkin LK, Demoski RK, Bellerdine J, Powers CN. The small blue cell dilemma associated with tamoxifen therapy. Arch Pathol Lab Med. 2001; 125:1047-50. Opjorden SL, Caudill JL, Humphrey SK, Salomao DR. Small cells in cervical-vaginal smears of patients treated with tamoxifen. Cancer. 2001; 93:23-8. Eells TP, Alpern HD, Grzywacz C, MacMillan RW, Olson JE. 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