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.

Anti-CD10 (56C6) is expressed variably in adrenocortical tumors and cannot be used to discriminate clear cell renal cell carcinomas

“…Because of the close anatomical relation of the adrenal gland with kidney and surrounding retroperitoneal fat, adrenal neoplasm may pose clinical and pathological diagnostic challenges. In this context, the distinction of adrenocortical carcinomas from renal cell carcinomas and hepatocellular carcinomas has been recognized as particularly difficult especially in core biopsies [5][6][7][8]. The practicing pathologist may not be confident enough to make a definitive diagnosis based only on histology, given the often overlapping morphologic appearances of these tumors.…”

Bilateral giant angiomyolipomas revealed after massive retroperitoneal hemorrhage: A case report

“…They are also known to be positive for other melanocytic markers such as HMB-50, tyrosinase, and microphthalmia-associated transcription factor. Other markers for AML are CD117 and CD68 19,20 . AMLs exhibit variable immunopositivity for myoid markers such as smooth muscle actin, musclespecific actin, desmin, and calponin.…”

Targeted therapeutic strategies for the management of renal cell carcinoma

“…RCC has been reported in 1–4% of TSC patients, and although the overall incidence parallels that of RCC in the general population, patients with TSC and RCC are younger (average age 28 years) [58]. Although ccRCC is the predominant malignant histologic subtype, other histologies have also been reported in this population [59]. …”