Clear Cell Renal Cell Carcinoma with Melanocytic Differentiation: A Case Report, with Review of the Literature

Case Report

Austin J Clin Pathol. 2014;1(3): 1015.

Clear Cell Renal Cell Carcinoma with Melanocytic Differentiation: A Case Report, with Review of the Literature

Kiran Krishne Gowda, Parimal Agrawal and Kim Vaiphei*

Department of Histopathology, Post Graduate Institute of Medical Education and Research, India

*Corresponding author: Kim Vaiphei, Department of Histopathology, Post Graduate Institute of Medical Education and Research, (PGIMER), Chandigarh, India

Received: July 08, 2014; Accepted: Aug 04, 2014; Published: Aug 05, 2014


Renal cell carcinoma consists of several subtypes, each of which has its own clinical features, and cytogenetic and molecular characteristics. Recognizing histologic patterns of RCC is important not only for correct diagnosis, but also for providing insight into biological behavior of the tumor and subsequent appropriate medical care for the patient. Pigments other than hemosiderin have been observed in renal cell carcinoma. It has been described in both clear cell and chromophobe subtypes of renal cell carcinoma. The nature of these pigmentations is consistent with melanin, neuromelanin, and lipochrome granules. We report a rare case of pigmented clear cell renal carcinoma with melanocytic differentiation. A review of cases of pigmented clear cell renal cell carcinoma in literature is also presented. Awareness of pigmentation in primary renal cell carcinoma is important in differentiating it from primary and metastatic malignant melanoma and other malignancies that can show pigmentation.

Keywords: Renal cell carcinoma; Pigment; Melanin


RCC: Renal Cell Carcinoma; EMA: Epithelial Membrane Antigen; PEComa: Perivascular Epithelioid Cell Tumor


Renal cell carcinoma (RCC) accounts for approximately 3% of adult malignancies and 0.1% to 0.3% of all pediatric neoplasms with 90%-95% of neoplasms arising from the kidney [1]. RCC has been classified into ten histologic subtypes: clear cell, multilocular clear cell, papillary, chromophobe, carcinoma of the collecting ducts of Bellini, renal medullary carcinoma, Xp11 translocation carcinomas, carcinoma associated with neuroblastoma, mucinous tubular and spindle cell carcinoma and renal cell carcinoma unclassified. Mixture of these distinct types is not infrequent. In addition, pigment other than hemosiderin has been documented in different types of RCC in adults [2-8] expanding the spectrum of the histologic features of RCC and increasing the difficulty of diagnosing the tumor. We report the first case of clear cell RCC exhibiting melanocytic differentiation in pediatric age group.

Case Presentation

A 12-year-old female child presented with complaints of abdominal pain. Abdomen examination revealed a soft tender mass measuring 4 cm in left lumbar region. Ultrasonography of abdomen revealed a mass in lower pole of left kidney which was confirmed on CT scan (Figure 1A). After presurgical evaluation, patient underwent radical nephrectomy which consisted of left kidney measuring 14 x 10 x 8 cm and ureter measuring 6.5 cm in length. Cut surface showed a circumscribed dark brown to tan tumor in lower pole measuring 6x5.5x5 cm, without any capsular breach (Figure 1B). Tumor was solid with focal areas of cystic degeneration (10% of total area). The remaining renal parenchyma appeared normal including pelvicalyceal system. On microscopy tumor cells were arranged in solid, alveolar and acinar growth pattern with rich sinusoidal network of delicate vascular channels (Figure 1D). Tumor was composed of cells with abundant clear-to-granular cytoplasm and centrally located nuclei with single prominent nucleoli (Fuhrman nuclear grade-III/ IV). In majority of tumor cells, dark brown pigment was observed in cytoplasm. The pigment was dark brown, granular, nonrefractile and stained blue-green with Schmorl's and black with Masson Fontana stain indicating it to be melanin (Figure 2). Immunostains for HMB- 45 and S-100 stained most of tumor cells positively, while cytokeratin and epithelial membrane antigen (EMA) were negative confirming melanocytic differentiation (Figure 3). Renal capsule was free of tumor tissue. The renal vessels and ureter were free of disease. A diagnosis of clear cell RCC with melanocytic differentiation (Furhman nuclear grade- III/IV; TNM stage I) of kidney was made. The patient is alive and well at 7 months follow-up.