[Sinonasal renal cell-like adenocarcinoma: a clinicopathological analysis of five cases].

To investigate the clinicopathological features, immunophenotype, differential diagnosis and prognosis of sinonasal renal cell-like adenocarcinoma. Retrospective analysis was performed on the cases of sinonasal carcinoma from August 2014 to December 2018 at Eye, Ear, Nose and Throat Hospital, Fudan University. Renal cell-like adenocarcinoma was screened for clinicopathologic feature analysis, and relevant literatures were reviewed. There were 460 cases of sinonasal carcinoma, among which 70 cases (15.2%) were adenocarcinoma, with five (1.1%) being renal cell-like adenocarcinomas. Four patients were male and one was female, with a mean age of 46.5 years (range 29-52 years). The main clinical manifestations were nasal obstruction and epistasis. A red polypoid mass was found under nasal endoscopy. Imaging showed nasal cavity and ethmoid sinus mass with invasion into surrounding structures and bone destruction. Microscopically, the tumor cells were arranged in nests, alveoli and microcapsules with abundant intervening capillaries, accompanied by hemorrhage. The cytoplasm of the cells was clear with low nuclear grade, and the nucleoli were inconspicuous. In some areas, the tumor invaded bone tissue. Immunohistochemical markers CKpan, CK7, CAⅨ, S-100 and vimentin were positive, with low Ki-67 proliferation index. RCC, CD10, PAX8, p63, SMA, HHF35, Calponin, CD117, TTF-1 and neuroendocrine markers Syn and CHG were all negative. EWSR1 and ETV6 gene rearrangements were not detected by FISH. All five patients underwent surgical resection after initial diagnosis. One patient underwent surgical resection after second recurrence and adjuvant radiotherapy, one patient received postoperative radiotherapy, one patient underwent surgical resection after recurrence, one patient had no recurrence and one patient received radiotherapy after recurrence. All five patients had no distant metastasis and survived without tumor up to December 2019. Primary sinonasal renal cell-like adenocarcinoma is a special subtype of low-grade non intestinal adenocarcinoma, with low incidence and inert biologic behavior. At present, most of the literatures are case reports. Before a diagnosis is made, other primary and metastatic clear cell tumors need to be excluded. Immunohistochemistry is helpful for diagnosis and differential diagnosis. Surgical resection is the mainstay of treatment, and may be supplemented by radiotherapy.