Clear Cell Papillary Renal Cell Tumors: A Study of 42 Tumors with Emphasis on the Fibrous Capsule, Cystic Component, and GATA3 Immunohistochemistry.

Clear cell papillary renal cell tumor is a common and sometimes underdiagnosed renal cell neoplasm. Its proper recognition is important because its diagnosis implies a remarkably high probability of indolent behavior. This study aimed to evaluate the frequency of a fibrous capsule, a cystic component, and a GATA3 expression in clear cell papillary renal cell tumors. We assessed 419 renal cell neoplasms from three institutions located in northeastern Brazil and identified 42 clear cell papillary renal cell tumors (from 39 patients), which were the fourth most common renal cell neoplasm. These tumors commonly exhibited fibrous capsules (all showed complete or partial capsules) and cystic component (93%). Eighteen out of 42 tumors (43%) showed some expression of GATA3, and weak and focal staining was common among the positive tumors. Clear cell papillary renal cell tumor must always be included in the differential diagnosis of predominantly cystic renal cell neoplasms. As GATA3 is inconsistently expressed in clear cell papillary renal cell tumors, it is not useful in this diagnosis.