[1621] Problematic Cavernous Hemangioma Variants and Other Benign Mimics

AN Mattis, S Fischer, H Makhlouf, W Tsui, S Cho, L Ferrell. UCSF, San Francisco; Univ Toronto, Toronto, Canada; AFIP, Washington, DC; Caritas Medical Centre, HK, Hong Kong

Background: Cavernous hemangioma (CH), the most common hepatic vascular tumor, typically consists of a single mass composed of large dilated spaces with a single endothelial lining covering septa with fibroblasts and scant smooth muscle cells. CH is usually not a diagnostic problem but we describe unusual CH variants and mimics, many that have previously not been well-described, but may cause diagnostic problems, including those that may be confused with malignancy.
Design: Ten cases of hepatic resections with unusual hemangioma-like lesions were reviewed. When possible, CD31, CD34, SMA, MIB-1, and EVG stains were used to assist in classifying the lesion.
Results: We classified our cases into two broad categories, unusual variants of CH (Type 1, 7 cases) and mixed or unclassified mimics of hemangiomas (Type 2, 3 cases). The CH variants (Type 1) included two subcategories. Type 1A were confined to the interior of the CH, and were problematic due to significant degrees of scarring and/or organizing thrombosis, resulting in increased cellularity and thickening of septa or lesions similar to the intravascular papillary endothelial lesion of Masson. Type 1B had CH-like vessels (CHLVs) not organized into the typical single CH, but composed of numerous clusters of CHLVs admixed with large zones of liver parenchyma within the body of a distinct mass lesion, or CHLVs present in predominatly periportal locations outside of a typical CH and dispersed diffusely in right and left lobes, suggesting a diagnosis of metastatic vascular tumor. Type 2 lesions were composed of capillary, venous, or small muscular vessels. One lesion had dilated sinusoids and hepatic vein-like vessels, typical of a localized venous malformation but that grossly mimicked CH. Two other lesions were more similar to capillary hemangiomas, one associated with similar lesions in the spleen and lymph nodes, and one similar to a multilobular hemangioma with spindle cell component. These lesions had a sinusoidal pattern of growth that resulted in a residual layer of hepatocytes in the intervening septa, histologic features that could mimic those of epithelioid hemangioendothelioma or angiosarcoma.
Conclusions: We describe unusual variants of CH and other types of hemangioma-like lesions, including rare unclassified types. Defining this expanded spectrum of hemangioma-like lesions may aid in their diagnosis and in understanding their development, progression, and outcome.
Category: Liver & Pancreas

Monday, March 22, 2010 1:00 PM

Poster Session II # 191, Monday Afternoon

 

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