Eosinophilic solid cystic renal cell carcinoma: A series of 3 cases elucidating the spectrum of morphological and clinical features of an emerging new entity

Eosinophilic solid cystic renal cell carcinoma (ESC-RCC) is a recently described entity, which demonstrates distinct clinical, pathological and molecular features. We present a series of three cases, the first to be reported from the Indian subcontinent. All three patients were over 50 years of age; and presented with a large kidney mass. One patient had a locally advanced disease while the other two presented with metastases. Microscopic examination revealed a tumor displaying solid-cystic and/or papillary areas composed of clear as well as eosinophilic cells in all three cases. On immunohistochemistry, all the three cases showed a unique CK20+/α-methyl-acyl-CoA-racemase + immunophenotype. Melan-A was focally positive in Case 2. Cytokeratin 7 was focally but strongly positive in Case 3. The two patients with metastatic disease were diagnosed on core biopsies and were advised oral tyrosine kinase inhibitor therapy. The third patient underwent upfront radical nephrectomy. Due to its peculiar morphology and immunoprofile, the diagnosis of ESC-RCC can be confidently made even on a core biopsy. Most cases reported till date had an indolent course. The metastatic presentation in two of our patients emphasizes the need to gather further evidence to ascertain the biological behavior of this emerging entity.