A Case Report of Metastatic Retroperitoneal Angiosarcoma Mimicking Reactive Angioendotheliomatosis

Figures

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  Figure 1. Diffuse red-purple plaques on the patient's trunk and arm

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  Figure 2. Histological and immunohistochemical aspects of the two cutaneous lesions a and b: Reactive angioendotheliomatosis shows dilated dermal and subcutaneous vessels disposed in diffuse, lobular, or mixed patterns. The latter vascular channels contain proliferations of small to enlarged endothelial cells that variably fill and often occlude vascular lumina (hematoxylin and eosin staining, ×100 and ×200 magnification). c and d: Reactive angioendotheliomatosis: seemingly disorganized arrangement of regular capillary vessels throughout the upper reticular dermis. This vascular growth pattern is often mistaken for angiosarcoma (hematoxylin and eosin staining, ×200 magnification). e and f: SMA membranous marker indication in the pericytic space surrounding the capillaries (×200 magnification). SMA: smooth muscle actin

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  Figure 3. Histological and immunohistochemical findings of renal and cutaneous angiosarcoma a: Angiosarcoma typically has ill-defined margins, and it varies in its degree of cytological atypia and architectural differentiation (×40 magnification). b: Renal angiosarcoma: a poorly differentiated tumor composed of sheets of epithelioid and spindle cells with amphophilic cytoplasm (×400 magnification). c and d: Cutaneous angiosarcoma: the dermis contains an ill-defined tumor composed of irregular vascular channels lined by hyperchromatic, moderately atypical vascular endothelial cells. There is a mild surrounding chronic inflammatory infiltrate (hematoxylin and eosin). e, f, and g: Well-moderately differentiated angiosarcoma invading the reticular dermis. This lesion shows well-formed vascular spaces lined by mildly atypical flattened endothelial cells (hematoxylin and eosin). h: Angiosarcoma typically shows membranous CD31 positivity (×200 magnification). i: Nuclear immunoreactivity for ERG, the most sensitive and specific endothelial marker for angiosarcoma (×400 magnification). ERG: erythroblast transformation specific regulated gene 1

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  Figure 4. Progression of the skin lesions in size and number on the patient's trunk and face