Answer: Acquired progressive lymphangioma

Histology: Sections show skin with angulated and anastomosing vascular spaces, some of which are dilated that dissect the dermis. Scattered perivascular, small lympho-plasmacytic infiltrates are also noted. The findings are consistent with acquired progressive lymphangioma (aka. benign lymphangioendothelioma).

Discussion: They typically consist of anastomozing often markedly dilated vascular structures involving the superficial dermis. In the deeper layers of the dermis, the vascular spaces may collapse and dissect the dermal collagen in an angiosarcoma-like pattern.

The lining endothelium is typically flat and monolayered, with little or no cytologic atypia and no evident mitoses. Some vascular structures can have papillary projections resembling papillary endothelial hyperplasia, and intravascular red blood cells may rarely also be present. In a study of 8 cases, immunohistochemistry showed variable endothelial cell reactivity for CD31 (7 of 8), CD34 (7 of 7), and factor VIII-related antigen (4 of 6). A smooth muscle cell layer was observed focally around the vascular spaces in six lesions. Acquired progressive lymphangioma is an uncommon benign lesion that should be distinguished from well differentiated angiosarcoma and from the patch stage and lymphangioma-like variants Kaposi’s sarcoma.

References:

Reference(s):
– Am J Surg Pathol. 2000 Aug;24(8):1047-57