title: Chromophobe renal cell carcinoma, oncocytic variant: a proposal of a new variant giving a critical diagnostic pitfall in diagnosing renal oncocytic tumors.
abstract: In chromophobe renal cell carcinoma (RCC), two forms of typical and eosinophilic variants have been reported to date. We have previously reported a new variant of chromophobe RCC, namely an oncocytic variant. However, little is known on the histological features of this variant. In this article, we report such five cases. Macroscopically, the tumor was well demarcated, but unencapsulated. The cut surface of the tumor showed brown in color, but neither hemorrhage nor necrosis was seen. Microscopically, the tumor consisted of predominant tubular configuration with or without various proportion of solid-sheet pattern. In one tumor, tumor cells microscopically invaded branches of renal vein. In addition, the constituting cells were characterized by the oncocytic cytoplasm, trivial to minimal variation in tumor size, indistinct to slightly distinct cell border, centrally located round nuclei and the absence of perinuclear halo. These characteristics entirely resembled renal oncocytoma. However, neoplastic cells immunohistochemically showed the diffuse and strong labeling for cytokeratin 7 and mitochondrial antigen in all cases. In addition, in fluorescence in situ hybridization (FISH) study the loss of more than four chromosomes among chromosomes 7, 10, 13, 17 and 21 was confirmed in all tumors and the diagnosis of chromophobe RCC was rendered. In conclusion, we propose a new variant, namely an oncocytic variant, of chromophobe RCC morphologically resembling renal oncocytoma and biologically showing characteristics of chromophobe RCC, and this recognition is practically crucial in the differential diagnosis from renal oncocytoma.
authors: Department of Diagnostic Pathology, Kochi Red Cross Hospital, Shin-honmachi 2-13-51, Kochi, Japan. kurochankochi@yahoo.co.jp
authors: Naoto
authors: N
authors: Kuroda
authors: Azusa
authors: A
authors: Tanaka
authors: Tadanori
authors: T
authors: Yamaguchi
authors: Kotaro
authors: K
authors: Kasahara
authors: Keishi
authors: K
authors: Naruse
authors: Yosuke
authors: Y
authors: Yamada
authors: Kanako
authors: K
authors: Hatanaka
authors: Nobuo
authors: N
authors: Shinohara
authors: Yoji
authors: Y
authors: Nagashima
authors: Shuji
authors: S
authors: Mikami
authors: Mototsugu
authors: M
authors: Oya
authors: Takeru
authors: T
authors: Hamashima
authors: Michal
authors: M
authors: Michal
authors: Ondrej
authors: O
authors: Hes
mesh_terms: D018249:Adenoma, Oxyphilic / Q000175:diagnosis* / Q000473:pathology; D000368:Aged; D000369:Aged, 80 and over; D001324:Autoantigens; D002292:Carcinoma, Renal Cell / Q000145:classification* / Q000175:diagnosis* / Q000473:pathology*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D053552:Keratin-7; D007680:Kidney Neoplasms / Q000175:diagnosis* / Q000473:pathology; D008297:Male
chemical_list: D001324:Autoantigens; D053552:Keratin-7; C062489:mitochondrial antigen 36 kDa