Monotypic epithelioid angiomyolipoma of the liver.
OBJECTIVE
Monotypic epithelioid angiomyolipoma is a recently recognized renal tumour, which is composed purely of epithelioid cells coexpressing markers of both smooth muscle differentiation and melanogenesis (HMB45). We report here the first case of monotypic epithelioid angiomyolipoma arising in the liver.


METHODS
A 30-year-old woman without tuberous sclerosis complex (TSC) was incidentally found to have a hepatic mass by ultrasonography. Grossly, the resected tumour showed a nodule-in-nodule appearance, with large areas of haemorrhagic necrosis. Microscopically, the tumour was composed of pleomorphic epithelioid cells with clear, eosinophilic cytoplasm. Neither adipocytes nor abnormal vessels were recognized in the tumour. Immunohistochemically, the tumour cells were strongly positive for HMB45 and S100 protein, focally positive for desmin, vimentin and smooth muscle actin, and negative for epithelial markers (cytokeratins, EMA). Ultrastructural analysis showed numerous dense granules with some striated ones resembling melanosomes, myofilaments and pinocytic vesicles in the cytoplasm. Molecular analysis showed no allelic loss of the TSC2 region or 12 other chromosomal regions. The patient is free of disease over 1 year after the operation.


CONCLUSIONS
We consider that this hepatic tumour is closely related to angiomyolipoma, and a counterpart of renal monotypic epithelioid angiomyolipoma.
Yamasaki
S
S
Department of First Pathology, Juntendo University, School of Medicine, Tokyo, Japan. shige@med.juntendo.ac.jp
Tanaka
S
S
Fujii
H
H
Matsumoto
T
T
Okuda
C
C
Watanabe
G
G
Suda
K
K
D000328:Adult; D018207:Angiomyolipoma / Q000737:chemistry / Q000473:pathology* / Q000648:ultrastructure; D014408:Biomarkers, Tumor / Q000032:analysis; D004273:DNA, Neoplasm / Q000032:analysis; D018572:Disease-Free Survival; D015622:Epithelioid Cells / Q000737:chemistry / Q000473:pathology / Q000648:ultrastructure; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008113:Liver Neoplasms / Q000737:chemistry / Q000473:pathology* / Q000648:ultrastructure; D009363:Neoplasm Proteins / Q000032:analysis
D014408:Biomarkers, Tumor; D004273:DNA, Neoplasm; D009363:Neoplasm Proteins