|Year : 2017 | Volume
| Issue : 1 | Page : 52-55
Collecting duct carcinoma: Sarcomatoid variant - A rare entity
Leena Konjengbam, Thingujam Bipin Singh
Department of Pathology, Babina Diagnostics, Imphal, Manipur, India
|Date of Web Publication||17-Jan-2017|
Department of Pathology, Babina Diagnostics, Soibam Leikai, Porompat, Imphal, Manipur
Source of Support: None, Conflict of Interest: None
Collecting duct carcinoma (CDC) is an extremely rare subtype of renal epithelial neoplasm arising from the distal segment of the collecting ducts of Bellini in the renal medulla. It accounts for <1% of all renal cell carcinoma cases. It has been reported to have a tendency toward early dissemination. This aggressive malignancy is difficult to be diagnosed despite its characteristic histological and immunohistochemical findings. We report a case of a CDC with sarcomatoid differentiation in a 64-year-old female who presented with a right renal mass and underwent right radical nephrectomy.
Keywords: Carcinoma, collecting duct, sarcomatoid, tubular
|How to cite this article:|
Konjengbam L, Singh TB. Collecting duct carcinoma: Sarcomatoid variant - A rare entity. J Med Soc 2017;31:52-5
| Introduction|| |
Collecting duct carcinoma (CDC) is a rare and aggressive malignancy comprising <1% of all renal epithelial tumors.  It may occur at any age; the mean age of presentation is approximately 53 years.  It is considered to be derived from the collecting duct of the kidney.  Symptoms may include flank pain, hematuria, and a palpable mass. The tumor is generally firm, gray-white, poorly circumscribed with infiltrative margins. It is often associated with regional and distant metastases. Although approximately 100 cases of CDC have been described in the literature, only a few cases of sarcomatoid CDC have been reported. CDC with sarcomatoid differentiation or dedifferentiated carcinoma or carcinosarcoma is extremely rare and follows a very aggressive clinical outcome; it has been documented that approximately 66% of patients die within 2 years of diagnosis.  It may be frequently mistaken for other renal cell carcinomas and pelvic urothelial carcinomas. A case of a 64-year-old female who presented with a right renal mass is being reported.
| Case Report|| |
A 64-year-old female presented with hematuria and right flank mass. Physical examinations were unremarkable, except for mild abdominal pain in the right lumbar region. Complete hemogram showed mild anemia (10.6 g/dl) and increased erythrocyte sedimentation rate (40 mm in the 1 st hr). Kidney function tests and serum electrolytes were within normal limits. Urinalysis showed occasional red blood cells per high power field. Imaging studies (ultrasonography, computed tomography scan) revealed a large right renal mass occupying almost the entire upper pole of the right kidney. No tumor extension into the renal vein or lymph node was observed on radiological examination. Based on the clinical and imaging findings, a radical nephrectomy of the right kidney was performed.
We received a nephrectomy specimen measuring 10 cm × 6 cm × 5 cm with relevant clinical information. On gross examination, the external surface was smooth with adherent perinephric fat. Cut sections showed a firm, solid, gray-white tumor in the middle and upper poles with infiltrative margins, predominantly involving the medulla and measuring 5 cm × 5 cm in maximum dimension [Figure 1]. The tumor was seen invading the capsule and extending into the perinephric fat on macroscopic examination. No areas of hemorrhage or necrosis were seen. Multiple bits were taken according to the protocol and processed for histological examination.
|Figure 1: A gray-white tumor with irregular infiltrating margins centered on renal medulla|
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On microscopic examination, a malignant tumor was seen displaying predominantly tubular structures lined by cells having moderate amount of eosinophilic cytoplasm and pleomorphic vesicular irregular nuclei with multiple prominent nucleoli [Figure 2]. The tumor cells were also seen arranged in sheets and occasional syncytial pattern. The intervening stroma was desmoplastic with moderate lymphoplasmacytic cell infiltration. Scattered tumor giant cells and many abnormal mitotic figures were noted. A few tubules were also seen lined by atypical cuboidal cells with evidence of hobnailing of nuclei [Figure 2] inset]. A few foci showed papillary structures with well-formed fibrovascular cores lined by cells with abundant eosinophilic cytoplasm, pleomorphic vesicular nuclei, and prominent nucleoli. Some areas (>25% <50%) showed spindle-shaped cells, having pleomorphic vesicular nuclei, evident of sarcomatoid differentiation, imperceptively merging with the adenocarcinomatous part [Figure 3]a and b. Lymphovascular emboli were seen. Immunohistochemical analysis showed strong membrane positivity for CK19 by the tumor cells [Figure 4]. Based on these features, a diagnosis of CDC of Bellini-Fuhrman's nuclear Grade IV with sarcomatoid differentiation was made.
|Figure 2: Photomicrograph showing infiltrating irregular tubules embedded in a fibrous stroma (H and E, ×100). Inset: Photomicrograph showing tumor cells with hobnailing of nuclei as indicated by arrow (H and E, ×400)|
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|Figure 3: (a) Photomicrograph showing spindle cells in interlacing fascicles (H and E, ×100). (b) Photomicrograph showing spindle cells having pleomorphic vesicular nuclei and prominent nucleoli. Note abnormal mitosis and plasma cell infiltrate indicated by arrows (H and E, ×400)|
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|Figure 4: Photomicrograph showing strong CK19 stain positivity by the tumor cells (×200)|
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| Discussion|| |
CDC is a very rare tumor, first described by Fleming and Lewi (1986) as a separate clinicopathological entity, arising from the distal collecting ducts of Bellini. The WHO international classification of tumors, 2004, has described it as Bellini duct carcinoma.  An internet search via PubMed showed only around five cases of sarcomatoid differentiation of CDC till 1997 with no further reports hence. Incidence has been reported higher in male adults, with a 2:1 male to female ratio. Patients have been described to usually present with hematuria, followed by abdominal pain and a palpable flank mass. General symptoms such as weight loss, fever, and anorexia have occasionally been described.
In our present case, the patient was a 64-year-old female who presented with complaints of flank pain and hematuria.
CDC is a rare pathologic type of renal cell carcinoma of medullary origin. They are infiltrative lesions with frequent perinephric extension. They are generally firm, gray-white, poorly circumscribed without extensive necrosis or hemorrhage. Invasion into a renal vein, perirenal and renal sinus fat may sometimes be found.  Microscopic features are somewhat variable, but the presence of an infiltrative tubular or tubulopapillary pattern, associated with intense desmoplasia and chronic inflammatory cell infiltrate in and around the tumor, aids in clinching the diagnosis. The tumor cells typically exhibit a high grade of nuclear pleomorphism and eosinophilic, basophilic, or amphophilic cytoplasm. Mitotic figures are frequent. Lymphovascular invasion is usually seen and metastases to regional lymph nodes, bone, adrenal glands, lung, and skin may occur.
CDC needs to be differentiated from other renal neoplasms such as papillary renal cell carcinoma, renal medullary carcinoma, renal metastatic carcinoma, and urothelial carcinoma with glandular differentiation. A well-demarcated lesion, yellow or brown color of the cut surface of the tumor, and minimal desmoplasia on histological examination are features in favor of papillary renal cell carcinomas. Immunohistochemically, papillary renal cell carcinoma shows frequent positivity for CK7 and occasionally, CD9. Renal medullary carcinoma, on the other hand, has significant reticular or solid pattern of growth and preferentially occurs in young patients of Black race with sickle cell trait.
They also need to be differentiated from metastatic carcinomas, in which case there may be a previous history of associated malignancies, especially mucin-producing adenocarcinomas from the colon. Adjacent in situ carcinoma component may be seen in the renal calyces or within the pelvis in urothelial carcinomas. They are immunoreactive for CK20, low molecular weight cytokeratin. Recently, they have also been reported to stain for transmembrane enzyme complex carbonic anhydrase IX. 
Occasionally, there may be foci of spindle cells in interlacing fascicular or storiform pattern with extremely pleomorphic vesicular nuclei. de Peralta-Venturina et al.  have reported in their study of 101 cases of sarcomatoid renal cell carcinoma, which over 50% of the cases resembled fibrosarcoma or malignant fibrous histiocytoma. Atypical hyperplastic changes or carcinoma in situ of the adjacent medullary collecting ducts may also be seen. Immunohistochemically, the tumor cells show high molecular weight keratin (34 betaE12, CK19) and sometimes, vimentin immunoreactivity. , EMA and lectins such as Ulex europaeus agglutinin I, peanut agglutinin, and soybean agglutinin are sometimes used as immunohistochemical markers. 
Cytogenetically, this tumor shows loss of heterozygosity and deletion of 1q32.1-32.2 and monosomies of chromosome 1, 6, 14, 15, and 22. 
In the present case, microscopic features, comprising a tubulopapillary growth pattern, marked nuclear atypia of the tumor cells with intense desmoplastic reaction, and focal sarcomatoid differentiation, led to the establishment of the diagnosis of CDC. In addition, tumor cells also showed strong CK19 membrane positivity on immunohistochemistry.
The patient however did not receive any chemotherapy or immunotherapy and died 3 months after the surgery.
| Conclusion|| |
CDC has a clinically rapid and aggressive malignant course and a poor prognosis. Radical nephrectomy, chemotherapy, radiation therapy, and immunotherapy have been described as modalities of treatment. Effective control has however been difficult and has been attributed to high rates of recurrence and early dissemination. Early detection and diagnosis of this disease are hence vital. Because of its histological mimics, the origin of the tumor should be determined using additional immunohistochemical, cytogenetic, and molecular studies to distinguish this tumor from other types of renal cell carcinomas. Since clinical presentations and imaging features of this tumor are nonspecific, histopathological and immunohistochemical analysis remain the mainstay of diagnosis of CDC.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]