title: Epithelioid angiomyolipoma of the kidney.
abstract: Epithelioid angiomyolipoma (eAMLoma) is an uncommon renal mesenchymal tumor with malignant potential and is frequently associated with tuberous sclerosis (TSC). It is composed of polygonal large-sized tumor cells arranged in an epithelioid manner. Differential diagnosis from renal cell carcinoma (RCC) is often challenging because of its epithelioid morphology. Herein is reported three cases of eAMLoma, involving one in a 28-year-old man with TSC and two in women without TSC (34 and 62 years of age, respectively). The male TSC patient had microscopic conventional AMLomas in the same kidney. All patients were positive for melanoma (reactive with HMB45 antibody, and positive for melan A, tyrosinase and microphthalmia transcription factor) and smooth muscle markers (positive for alpha-smooth muscle-specific actin), but not for epithelial markers (cytokeratin, epithelial membrane antigen). In particular, the translocation RCC is an important differential diagnostic candidate, in terms of the positive reaction with HMB45 and morphological similarity. The present tumor samples did not show any reactivity for transcription factor binding to IGHM enhancer 3 or transcription factor EB, which excluded the possibility of translocation RCC. The possibility of eAMLoma should be evaluated as a diagnostic candidate, especially in cases of renal tumors (i) in young patients; (ii) associated with TSC; or (iii) with an epithelioid morphology and a high nuclear grade.
authors.affiliation: Division of Anatomical and Surgical Pathology, Yokohama City University Hospital, Yokohama, Japan.
authors.forename: Ikuma
authors.initials: I
authors.lastname: Kato
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Inayama
authors.forename: Shoji
authors.initials: S
authors.lastname: Yamanaka
authors.forename: Hisashi
authors.initials: H
authors.lastname: Ohshiro
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Gomi
authors.forename: Sumiko
authors.initials: S
authors.lastname: Shirai
authors.forename: Ichiro
authors.initials: I
authors.lastname: Aoki
authors.forename: Hiroji
authors.initials: H
authors.lastname: Uemura
authors.forename: Yasuhide
authors.initials: Y
authors.lastname: Miyoshi
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Kubota
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yao
authors.forename: Yoji
authors.initials: Y
authors.lastname: Nagashima
mesh_terms: D000328:Adult; D018207:Angiomyolipoma / Q000150:complications / Q000378:metabolism / Q000473:pathology*; D002292:Carcinoma, Renal Cell / Q000473:pathology; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007680:Kidney Neoplasms / Q000150:complications / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D014402:Tuberous Sclerosis / Q000150:complications