Sinonasal Renal Cell-Like Adenocarcinoma: A Report of a Rare Entity With Emphasis on Its Association With Von Hippel Lindau Syndrome.

Sinonasal renal cell-like adenocarcinoma (SNRCLA) is a rare malignant sinonasal tumor with relatively indolent clinical course. Clinically, it could be asymptomatic or show non-specific symptoms such as epistaxis, nasal obstruction, or hyposmia. Diagnosis of the lesion is challenging, especially in small biopsies, and requires clinical, radiological, histopathological, and ancillary tests to characterize the lesion accurately. We herein report a case of a 41-year-old female with a nasal mass noted two years ago, which presented initially as frequent epistaxis from the right side. Histopathological examination revealed proliferation of clear cells associated with hemorrhagic background forming follicular and glandular structure and dense eosinophilic secretion. Tumor cells were diffusely positive for CK7, EMA, and inhibin, while they were negative for CK20, P63, CK 5/6, CD10, renal cell carcinoma (RCC), TTF1, PAX8, CEA, and GATA3. The proliferation index (KI67) was less than 5%. The diagnosis was consistent with SNRCLA. The patient has no recurrence and no symptoms after one year. Thus, our study reports a rare case of SNRCLA with a discussion of the histological features and its association with von Hippel Lindau syndrome.