PLEOMORPHIC HYALINIZING ANGIECTATIC TUMOR OF THE MALE BREAST: A HERETOFORE UNREPORTED OCCURRENCE. M. Bisceglia (1), F. Tallarigo (2), S. Squillaci (3), I. Putrino (2), N. Zizzi (5). Department of Pathology, IRCCS ”Casa Sollievo della Sofferenza” Hospital, San Giovanni Rotondo (1). Department of Pathology, “San Giovanni di Dio” Hospital, Crotone (2,5). Department of Pathology, Hospital of Vallecamonica, Esine (3).

In 1996 Smith MEF and coauthors coined the term “pleomorphic hyalinizing angiectatic tumor” (PHAT) to indicate a distinctive mesenchymal tumor of soft tissue (ST) of intermediate malignant potential that may be mistaken for both sarcomatous and benign lesions (1,2). PHAT of ST is a well-defined tumor distinguished by prominent angiectatic blood vessels surrounded by perivascular hyaline material and sheets of spindle and pleomorphic cells, mostly occurring in the subcutaneous tissue. PHAT has recently been incorporated into the WHO classification of ST tumors (2). Recently, Folpe and Weiss (3), from their observation of early PHAT lesions, hypothesized that the vascular changes are an early and pivotal event occurring even without a significant spindle cell proliferation. Introduction.

Only 80 histologically proven cases have been reported so far, 45 in women (60%) and 30 men (40%), with patients' age ranging from 10 to 89 years (average 54.7). The most common site of occurrence are the lower extremities, but even trunk, upper extremities, inguinal triangle and buttock are on record. PHAT in ST of both visceral organs and body cavities was reported only twice, and we are unaware of any case occurring in ST of the reproductive organs and breast. We report herein on a case of PHAT arising in male breast and describe its phenotypic and immunohistoche- mical features (3).

A 75-year-old man was referred to the Department of Surgery of “S. Giovanni di Dio” Hospital, Crotone, complaining of a painless slowly growing mass of several years duration. The lesion was located in his left breast, measuring 8 cm in its largest diameter on ultrasound and mammographic investigations. Case Report.

Mammogram – left breast. A highly dense and well-circumscribed nodular mass is seen.

Following FNA cytology examination, which resulted in a diagnosis of malignancy (C5), radical mastectomy with axillary lymphnode dissection was performed. At pathology the tumor exhibited features identical to those of PHAT of other sites. Grossly it was circumscribed but unencapsulated.

Histologically The tumor architecture was highly vascularized with variably sized, ectatic, hyalinized blood vessels, partly thrombosed, and displaying subendothelial fibrin deposits. The tumor cellularity consisted of a mixture of spindle, to plump to roundish-stellate pleomorphic cells. Tumor cells had a distinct cytoplasmic border and were eosinophilic, with some intranuclear inclusions or cytoplasmic hemosiderin granules. The mitotic rate was negligible. Small lymphocytes and mast cells were scattered throughout.

At immunohistochemistry, the tumor cells were diffusely positive for vimentin. They were also focally positive for EMA. Stainings for CD34, desmin,  -SMA, S-100, CD31 and cytokeratins were negative. The proliferative activity with MIB-1 was lower than 1%.

VimentinEMA CD34S100 pr

Results These findings were consistent with the diagnosis of PHAT of the breast (1,2,4,5). The 24 axillary lymph nodes isolated were negative.

PHAT in the breast needs to be differentiated from both mesenchymal lesions arisen from non-specialized mammary stroma (i.e., malignant fibrous histiocytoma, solitary fibrous tumor, ancient scwhannoma, hemangioma and hemangiosarcoma) and mesenchymal lesions arisen from specialized stroma (myofibroblastoma, benign and malignant phyllodes tumor), as well as from primary breast metaplastic squamous cell carcinoma. Discussion

PHAT has to be considered in the differential diagnosis of several of mammary spindle cell and pleomorphic neoplasms. We described herein the first case of PHAT in the (male) breast. Awareness of this possible occurrence should allow the correct diagnosis and avoidance of unnecessary aggressive therapy.

1.Smith MEF, Fisher C, Weiss SW. Pleomorphic hyalinizing angiectatic tumor of soft parts. A low-grade neoplasm resembling neurilemoma. Am.J.Surg.Pathol. 1996: Bisceglia M, Fisher C, Suster S, Kazakov DV, Cooper K, Michal M. Tumoral, quasitumoral and pseudotumoral lesions of the superficial and somatic soft tissue: new entities and new variants of old entities recorded during the last 25 years. Part III: Excerpta I. Pathologica 2004; 96: 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: References

4.Tallarigo F, Squillaci S, Putrino I, Zizzi N, Bisceglia M. Pleomorphic hyalinizing angiectatic tumor of the male breast: a heretofore unreported occurrence. Pathol Res Pract., in press. 5.Weiss SW. Pleomorphic hyalinizing angiectatic tumour of soft parts. In: Fletcher CDM, Unni KK, Mertens F, ed. WHO classification of Tumours: Pathology and genetics of tumours of soft tissue and bone. Lyon, France: IARC Press;2002:191.