[1726] Small Vessel Hepatic Hemangioma, an Atypical Hemangioma Variant in Adult Liver

Ryan Gill, Venancio Alves, Hala Makhlouf, Christine Sempoux, Swan Thung, Linda Ferrell. UCSF, San Francisco; Univ. of Sao Paulo/Medicine, Sao Paulo, Brazil; AFIP, Washington, DC; Universite Catholique de Louvain, Brussels, Belgium; Mt. Sinai Med. Ctr. Sch/Med., New York

Background: We have encountered rare atypical vascular lesions in the liver, not previously described, which are composed entirely of small vessels, often with an infiltrative border, and which may mimic well-differentiated angiosarcoma on biopsies. This study aims to further characterize these lesions.
Design: Small vessel hemangioma (SVH) samples (n=8) ranged from core biopsies (n=3) to partial resections (n=4) to autopsy (n=1). When possible, CD31, CD34, Ki-67, and p53 immunostains were performed. Proliferative index (PI) represents percentage of Ki-67 positive tumor nuclei/HPF. Benign vascular liver tumors (cavernous hemangiomas (CH), n=10) as well as malignant vascular liver tumors (epithelioid hemangioendotheliomas (EHE), n=8, and angiosarcomas (AS), n=7)) were similarly evaluated.
Results: The average age for SVH patients was 49 (range 34-83, n=7), mostly men (6/7). All cases (n=7) represented an incidental finding detected by imaging or at autopsy, usually a single lesion. The average size was 1.8 cm (range 0.7-4 cm, n=6). One patient had a similar splenic lesion. Recognition as hemangioma was not possible on imaging in at least one case. No patients, for which data is available, have died of disease (12 months maximum follow up). Lesions were uniformly composed of small vessels, usually with an infiltrative border and entrapped bile ducts, and occasionally with extramedullary hematopoiesis. Cytologic atypia and mitotic activity were not present. All cases were positive for CD31 and CD34 (n=5), negative for p53 (n=4), and overall had a low PI (average PI=4%, range 0-10%, n=6). By comparison CH did not show Ki-67 labeling (PI=0%, n=10), EHE had a similar average PI (6%, range 0-12%, n=8), and AS had a higher average PI (32%, range 15-50%, n=7). CH also did not demonstrate p53 staining, but a subset of EHE and AS had strong nuclear staining (EHE 3/8; AS 2/7).
Conclusions: Small vessel hepatic hemangiomas are a distinct rare variant of hemangioma encountered in adults. These lesions are typically identified as an incidental finding. The infiltrative border may raise concern for well-differentiated angiosarcoma on biopsy. The PI is above that which is typically seen in benign cavernous hemangioma and the lack of strong nuclear p53 staining argues against consideration as angiosarcoma. Given limited outcome data, this lesion may be one of uncertain malignant potential and we recommend excision if possible.
Category: Liver

Tuesday, March 20, 2012 1:00 PM

Poster Session IV # 241, Tuesday Afternoon

 

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