Pleomorphic hyalinizing angiectatic tumor Dr. M. Michal Sikl's Department of Pathology Laboratore Spec. Diagnostiky Medical Faculty Hospital Alej Svobody 80, 304 60 PILSEN, Czech Republic

Case History: A 76 year-old woman presented with a tumor in the left axilla 3,5 cm in the diameter. The tumor was well circumscribed, with dot-like small vessels on cut surface. A year after the original excision the lesion recurred in the same place in the left axilla. The recurrent tumor was a well circumscribed unencapsulated nodular lesion 3 x 2 x 3 cm, and it caused some scarring of the surrounding soft tissues of the anterior axillary region. Histologically the original tumor was formed of ectatic vessels with fibrinoid change in the walls of the vessels. It had pleomorphic areas containing cells with atypical mitoses mostly seen in the peripheral parts of the tumor. The original neoplasm was classified as pleomorphic hyalinizing angiectatic tumor of soft parts. The recurrent tumor looked entirely different from the original lesion and it was a frankly malignant tumor composed of pleomorphic spindle to epithelioid cells set in a myxoid background. It lacked ectatic vessels and it was devoid any resemblance to pleomorphic hyalinizing angiectatic tumor. It was classified as myxofibrosarcoma grade II. according to the WHO classification. Both original and recurring lesions were immunohistochemically negative with antibodies to S-100 protein, neurofilaments, cytokeratins, EMA, muscle actins, smooth muscle actin and desmin. The patient is currently without signs of recurrence and metastasis one year after the last excision. The slide submitted to the seminar comes from the original excision. Slide 1 Click to view with ImageScope Click to view with a Web-Based Viewer Diagnosis Pleomorphic hyalinizing angiectatic tumor of soft parts with sarcomatous areas recurring as myxofibrosarcoma grade II. Comment Pleomorphic hyalinizing angiectatic tumor (PHAT) is a rare tumor, only some 50 cases of the entity have been described so far [1]. Although is generally assumed that it was first described by Smith et al in 1996 [2], probably the very first descriptions of the tumor in the literature are the abstracts of Tsang et al [3] where the authors called the tumor as symplastic hemangioma and that of Smith and Weiss [4]. PHAT occurs principally in the superficial soft tissues of the distal extremities and shows heavily hyalinized, fibrin containing vessels, spindled and pleomorphic stromal cells with frequent intranuclear inclusions and a variable inflammatory component. It is a neoplasm occurring mostly in the adults with a wide age range (10-83, a median 51 years) and with a slight female predominance [5]. Most patients are cured by local excision, notwithstanding rarely, PHAT can behave quite aggressively. In one case PHAT recurred 3 years later as myxoid pleomorphic sarcoma [5], and one case o putative cutaneous myxofibrosarcoma had some features of PHAT [1]. The inner parts of our tumor were indistinguishable from PHAT and the peripheral parts had areas with sarcomatous morphology revealing pleomorphism and numerous mitoses including atypical once. A year after the original excision the lesion recurred as a pleomorphic sidle cell sarcoma. In this respect the case is similar to the cases published by Mitsuhashi et al [1] and that of Folpe et al [5]. References Mitsuhashi T, Barr RJ, Machtinger LA, Cassarino DS. Primary cutaneous myxofibrosarcoma mimicking pleomorphic hyalinizing angiectatic tumor (PHAT). A potential diagnostic pitfall. Am J Dermatopathol 2005;27:322-326 Smith MEF, Fisher C, Weiss SW. Pleomorphic hyalinizing angiectatic tumor of soft parts. A low grade neoplasm resembling neurilemoma. Am J Surg Pathol 1996; 20:21-29. Tsang WYW, Chan JKC, Fletcher CDM, Rosai J. Symplastic hemangioma: a distinctive vascular neoplasm featuring bizarre stromal cells. Int J Surg Pathol 1994;1:202. Smith MEF, Weiss SW. Low grade angiectatic sarcoma with pleomorphic features: a distinctive tumor resembling neurilemoma. Mod Pathol 1994;7:10A. Folpe AL, Weiss SW. Pleomorphic hyalinizing angiectatic tumor: analysis of 41 cases supporting evolution from a distinctive precursor lesion. Am J Surg Pathol. 2004;28:1417-25.