Atypical cellular chorangioma of the placenta.

A rare and atypical type of chorangioma is presented. The tumor was unusual in three aspects: (a) clinically, it was delivered after the placenta and required lavage; (b) grossly, the lesion was quite large; and (c) most importantly, it exhibited histologic features suggestive of sarcoma. Immunochemical staining of the tumor for factor VIII antigen demonstrated its endothelial origin. However, the tumor lacked evidence of invasion or biological aggressiveness. We propose that peculiar lesions of this type be termed "atypical cellular chorangiomas." No documented case of chorangiosarcoma could be identified in the literature.