Pleomorphic hyalinizing angiectatic tumor of soft parts.

A case of recently described pleomorphic hyalinizing angiectatic tumor (PHAT) of soft parts is reported. The subcutaneous solid tumor arising in the axilla of a 58-year-old man was histologically characterized by sheets of mitotically inactive oval and pleomorphic cells, intranuclear cytoplasmic inclusions, and clusters of ectatic vessels with perivascular hyalinization. Mono- and multinucleated giant cells were also present. A hemangiopericytoma-like pattern of vascularity, pseudovascular spaces, stromal collagen with degenerative changes, and immunoreactivity for CD34 were observed. Since these features were very similar to those of solitary fibrous tumors of various sites and newly categorized giant cell angiofibroma, it is considered that PHAT, solitary fibrous tumor, and giant cell angiofibroma may be in the same family of tumor. The tumor was diploid with a low S-phase fraction. The patient was well with no evidence of disease for 23 months.