Fine needle aspiration cytology of a low grade myxoid renal epithelial neoplasm: a case report

Mucinous tubular and spindle cell carcinoma of the kidney: Diagnosis by fine needle aspiration and review of the literature

Renal mucinous tubular and spindle cell carcinoma (MTSCC) was recently described as a distinct subtype of renal cell carcinoma (RCC) in the 2004 World Health Organization classification of kidney tumors. MTSCC is a rare low grade malignancy with < 100 cases reported in the literature. To the best of our knowledge, there are 5 case reports with a total of 6 patients describing its diagnosis by fine needle aspiration (FNA). All of these cases were diagnosed as conventional RCC on FNA. Subsequent excisions proved them to be MTSCC. We herein report a case in a 67-year-old male. He presented with abdominal pain and was found to have a new colon adenocarcinoma with metastasis to the liver and lungs. The extent of disease made the patient ineligible for surgical excision, and he received chemotherapy. Work-up also revealed a kidney mass which was later biopsied by FNA and core biopsy. The tumor was composed of epithelial and spindled cell components embedded in a myxoid background. It was positive for CK7, AMCAR, vimentin, and epithelial membrane antigen. The tumor was diagnosed as MTSCC. One year later the kidney mass remained stable. However, the patient developed new metastasis to the liver from colonic primary. The kidney mass was not resected. Although rarely encountered in FNA cytology of the kidney, we believe the cytologic features of this tumor are distinctive and are different from conventional and other subtypes of RCC. Therefore, its accurate diagnosis on FNA is possible once pathologists are aware that MTSCC should be considered in the differential diagnosis of kidney tumors.

Fine needle aspiration biopsy of renal mucinous tubular and spindle cell carcinoma: report of two cases

Mucinous tubular and spindle cell carcinoma (MTSCC) is a rare renal tumor. Here we report two cases of MTSCC which were initially evaluated by fine needle aspiration biopsy (FNAB) and followed by surgical resection of the tumors. The cytomorphologic features of MTSCC were characterized by aggregates of relatively uniform, predominantly oval to spindle cells intermixed with abundant metachromatic myxoid matrix. Only rare epithelioid tumor cells with vacuolated cytoplasm were present. Immunohistochemically, the tumor cells were positive for CK7, CK19, CD10, vimentin, E-cadherin, alpha-methyl CoA racemase, and negative for CK903 and CK20. EMA and carbonic anhydrase IX immunoreactivity was seen in one of the two cases. Multiple chromosomal losses involving chromosomes 1, 2, 17 and likely chromosome 7 were revealed by fluorescence in situ hybridization (FISH). These cytomorphologic, immunophenotypic, and cytogenetic features were helpful for including this entity in the differential diagnosis of renal cell carcinomas.

Mucinous tubular and spindle cell carcinoma of the kidney: cytopathologic findings

A 54-year-old woman was hospitalized for flank pain and acute renal failure when imaging studies revealed a 5.2 cm mass in the left kidney. She was referred for fine needle aspiration of the lesion, which showed an epithelial tumor with round to oval nuclei associated with strands of metachromatic stromal tissue. Cytopathologic diagnosis was consistent with renal cell carcinoma. Subsequent nephrectomy was performed and the surgical pathology specimen showed a mucinous tubular and spindle cell carcinoma of the kidney. The patient has done well post-operatively with 10 months of benign follow-up.

Recently Described and Emphasized Entities of Renal Neoplasms

Context.—Recent advances of molecular biology and cytogenetics of renal cancer have resulted in the new classification of renal neoplasms and a number of subtypes are identified and emphasized. In addition, rare nonepithelial renal neoplasms are identified and characterized. Familiarity with these entities will help make the most accurate diagnosis and guide the treatment and follow-up of patients with renal neoplasm.

Objective.—To review the clinicopathologic entities of renal neoplasms that are recently defined or emphasized. Their clinical, gross, microscopic, and immunohistochemical features, as well as specific cytogenetic or molecular abnormalities, are discussed. Important differential diagnoses of each entity are also briefly discussed.

Data Sources.—Extensive review of published literature and our experience.

Conclusions.—A number of new entities of renal neoplasms or genetically defined renal cell carcinomas have been identified or emphasized because of their unique genetic or molecular changes. Recognition of these entities becomes important as some of them have different biologic behavior and treatment strategies may be different.

Myxoid renal tumor with myoepithelial differentiation mimicking a salivary gland pleomorphic adenoma: description of a case

We herein report an unusual case of a low-grade myxoid renal epithelial neoplasm, with peculiar and previously unreported morphologic and immunohistochemical features. The lesion was characterized by noninfiltrative borders, myxoid stroma and elongated tubular and cordlike epithelial structures. These were lined by 2 different epithelial cell types, flat and elongated basal cells and cuboidal to spindle shaped eosinophilic luminal cells, with low-grade nuclear features and a few small nucleoli. The lesion morphologically resembled a pleomorphic adenoma of the salivary gland. The immunohistochemical profile interestingly confirmed the myoepithelial differentiation of the basal epithelial layer, as demonstrated by the coexpression of several myoepithelial markers such as p63, caldesmon, calponin, smooth muscle actin, and S-100, together with epithelial markers such as low and high-molecular weight cytokeratins. The tumor proved benign at follow-up. A definitive classification and histogenetic interpretation of this previously unreported tumor type awaits description of further cases showing similar features which, perhaps, as it may happen, went so far unnoticed.

Mucinous tubular and spindle cell carcinoma of kidney is probably a variant of papillary renal cell carcinoma with spindle cell features

Mucinous tubular and spindle cell carcinoma is a rare and newly described type of renal cell carcinoma (RCC) with a relatively indolent behavior. However, its histogenetic origin or line of differentiation remains unclear. Twelve cases of mucinous tubular and spindle cell carcinoma were identified and retrieved from the files of 3 institutions. Detailed morphological features, as well as their immunohistochemical profile established with markers of proximal renal tubules (RCC marker antigen, CD15, and alpha-methylacyl-CoA racemase) and of distal renal tubules (kidney-specific cadherin and cytokeratin 7), were studied. The age range of the patients was 35 to 73 years with a median of 56 years. The male to female ratio was 1:3. All of the patients were alive with follow-up between 4 and 38 months. All the tumors were confined to the kidney with a mean tumor size of 6.9 cm (range, 1.8-17 cm). The tumors were composed of variable proportions of tubular and spindle cell areas with focal to prominent mucinous or myxoid stroma. Foamy macrophages were seen in 10 cases and were prominent in 4 cases. A focal compressed tubulopapillary growth pattern was seen in 10 cases. The tumor cells were uniformly cuboidal with ovoid to round nuclei and inconspicuous nucleoli (Furhman nuclear grade 3 in 6 cases). Focal necrosis was seen in 3 cases. Immunostains showed that tumors were positive for RCC marker antigen (11/12), alpha-methylacyl-CoA racemase (11/12), CD15 (8/12), CD10 (2/12), kidney-specific cadherin (1/12), and cytokeratin 7 (11/12). Its morphological features as well as a strong preferential expression of proximal tubule markers suggest that this tumor is a type of RCC with proximal tubular differentiation, which appears closely related to or represents a morphological variant of papillary RCC.