Unilateral gynecomastia and pseudoangiomatous stromal hyperplasia in neurofibromatosis: case report and review of the literature.

In this article, we describe unilateral gynecomastia and pseudoangiomatous stromal hyperplasia (PASH) in a case of type-1 neurofibromatosis (NF-1). It is important to distinguish PASH from fibroadenoma clinically, and from true blood capillaries and angiosarcoma histologically. In the present case, giant multinucleated cells lined the pseudovascular spaces, which was markedly different from that of conventional breast PASH. The origin of PASH has been reported to be either the fibroblast or the myofibroblast phenotype and may be affected by endocrine signaling because many cases have been reported in premenopausal women, and cases are often estrogen (ER) and progesterone receptor (PR) positive. However, previous reports have identified PASH in NF-1 in juvenile males only, and the cases were negative for α-SMA, ER and PR. The cause and prognosis of PASH in NF-1 may be distinguished from that of conventional PASH, and mast cells, histiocytes and CD54 may play roles.