Clear cell sarcoma of kidney. Two cases in adults

Clear cell sarcoma of kidney (CCSK) is an aggressive renal tumor occurring most frequently in the second and third years of life. Although it has been reported in the literature in patients as old as 21 years of age, there has been no report focusing on adults with CCSK. The authors describe two cases of CCSK in men and the findings at autopsy.

Histologically, the renal tumors consisted of a homogeneous proliferation of polygonal or short spindle cells with faintly eosinophilic cytoplasm supported by a network of small vessels. Ultrastructurally, clusters of tumor cells were surrounded by collagen bundles. Elongated cytoplasmic processes, dilated rough endoplasmic reticulum, and intermediate filaments in the cytoplasm; primitive desmosome-like junctional structures; and incomplete basal lamina were observed. Immunohistochemically, tumor cells had positive results only for vimentin. Cytokeratins, epithelial membrane antigen, desmin, myoglobin, S-100 protein, neuron-specific enolase, and chromogranin A were not detected in the tumor cells. Both patients died within 2 years of onset of disease, and autopsy showed widespread metastases, especially in the soft tissue and bone.

Morphologic findings and an aggressive clinical course with metastasis to the bone and soft tissue are supportive of the diagnosis of CCSK in these patients.