Case Number : Case 2093 - 14 June 2018 Posted By: Raul Perret

After ruling out hhv8  favour aneurysmal fibrous histiocytoma

Angiomatoid fibrous histiocytoma

Agree. 

Yes, this is a classical case of aneurysmal dermatofibroma. The presence of collagen entrapment at the periphery of the tumor (last pic) is a good clue for the diagnosis of this neoplasm. Although diagnosis of dermatofibroma and its variants should be based on morphological grounds, HMGA2 expression is frequently seen in this group of tumors. Regarding the differential with angiomatoid fibrous histiocytoma, the absence of a prominent peripheral lymphocytic inflammatory component (usually forming primary and secondary follicles) and the collagen entrapment are good features for ruling it out. In addition, AFH shows desmin expression in 50% of cases and has a rearrangement of EWSR1.