Case 2 -
Mucinous Tubular and Spindle Cell Carcinoma of the Kidney
Wayne State University
Click on each slide thumbnail image for an enlarged view
A 70 year old man was found to have mass involving the right kidney during work up for right upper
quadrant pain. There was no significant past history. A radical nephrectomy was performed. The
gross description from the pathology report indicated that the kidney contained a "2.0 x 2.0 x 1.8 cm
white-grey, fleshy tumor. It is located within the center of the specimen, and appears to involve
part of the cortex and an entire pyramid."
Case 2 - Figure 1 - Mucinous tubular and spindle cell carcinoma. Low power photomicrograph illustrating the sharp circumscription of the tumor from the adjacent kidney.
Case 2 - Figure 2 - Mucinous tubular and spindle cell carcinoma. Intermediate power photomicrograph illustrating the tightly packed tubules with many having long open tubular profiles.
Case 2 - Figure 3 - Mucinous tubular and spindle cell carcinoma. Intermediate power photomicrograph highlighting the tubules some of which are collapsed without apparent lumens.
Case 2 - Figure 4 - Mucinous tubular and spindle cell carcinoma. High power photomicrograph illustrating the tubules. Note the prominent basal lamina around the tubules.
The broad area of tumors of collecting duct derivation is undergoing considerable change and
redefinition [Srigley, 1998]. Most urologic pathologists have taken to restricting the term "collecting
duct carcinoma" to the classically described, high grade tumor with papillary ductal architecture and
stromal desmpolasia. The tumors that develop in association with sickle cell trait are dealt with
separately under the term medullary carcinoma [David, 1995; Swartz, 2002].
An initial report of low grade collecting duct carcinoma included at least 2 distinct tumors and these
have now been assigned nomenclature of their own ( mucinous tubular and spindle
cell carcinoma and tubulocystic carcinoma). It must be appreciated
that that this area will continue to mature in the coming years.
The most current classifications of renal tumors, scheduled to be published early in 2004 represent an
extension of the 1997 consensus classification [Störkel, 1997] and include neoplasms recently defined on
both morphologic and cytogenetic grounds. Mucinous tubular and spindle cell carcinoma is on such entity.
Tubulocystic carcinoma is just in the process of being defined (one abstract at this meeting presented a
series of cases [Amin et al]) and is not included in these classifications but likely will emerge in
future classifications as a distinct entity. A coordinated effort was made to bring the 2003 WHO
classification [Eble, 2004] and that presented in the 4th edition of the AFIP fascicle in line
| Classification of Renal Cell Carcinoma (AFIP 4th Ed)|
| Clear cell|
| Multilocular cystic|
| Chromophobe cell|
| Collecting duct|
| Mucinous tubular and spindle cell|
| Xp11.2 associated carcinomas|
The original paper on low-grade collecting duct carcinoma of the kidney included tumors that now are
now designated mucinous tubular and spindle cell carcinoma [MacLennan, 1997]. This uncommon pattern of
RCC that has been postulated to be of collecting duct and possibly loop of Henle origin. It occurs
predominantly in females and in middle age[Parwani, 2001; Hes, 2002; Srigley, 2002; Rakozy, 2002]. Most
cases are single though multifocality has been described. An association with nephrolithiasis was
identified in 3 of 11 cases reported by Hes et al. . In one series a single case had a documented
regional lymph node metastases [Hes, 2002] indicating the potential for malignant behavior, though
information is limited.
Grossly, mucinous tubular and spindle cell carcinomas are solid, pale tan to yellow, to gray-white
lesions that may have slight focal areas of necrosis or hemorrhage. Histologically, they manifest
elongated branching tubules in a bubbly myxoid stroma. The collapsed tubules result in a cord-like
pattern and spindle cell areas are also present. The tubules are striking with characteristic long
profiles. The basal lamina, around the tubules, is highlighted by PAS staining. The cells are cuboidal
with scant, clear to pale, acidophilic cytoplasm and low-grade nuclear features. The background is
mucinous with basophilia and a characteristic bubbly appearance.
Immunohistochemical studies have had widely varied results, but most tumors express pan cytokeratins,
CK7, CK18, CK19 and 34ßE12. EMA is positive in the majority with less frequent positivitiy for vimentin
and CD15. Ulex europus is positive in most. [Parwani, 2002; Rakozy, 2002;
Srigley, 2002]. Although the pattern generally supports a collecting duct origin, the results are very
Ultrastructurally the tumor consists of collapsed tubules with the lining epithelial cells having a
simple appearance with scattered, short microvilli on the surface reminiscent of the loop of Henle. The
"spindled" areas reflect these collapsed tubules with no visible lumens.
Cytogenetic studies have demonstrated consistent losses involving chromosomes, 1, 4, 6, 8, 9, 13, 14,
15 and 22, supporting this lesion as being a distinctive entity [Rakozy, 2002; Srigley, 2002].
In the 3rd series AFIP fascicle, Farrow  illustrated an unusual tumor
with a multicystic gross appearance and striking mixture of tubules and micro/macro cysts histologically.
Similar cases were subsequently included in the low-grade CDC paper [MacLennan, 1997]. We have seen a
large number of cases now that are remarkable for the uniformity on gross and microscopic characteristics
[Amin, 2004]. The tubules and cysts are lined by cuboidal to columnar cells with eosinoiphilic
cytoplasm. Nuclei are uniform and contain nucleoli. In our experience approximately 10% metastasize.
Whether these truly derive from the collecting system is uncertain.
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