Postradiation Angiosarcoma of the Skin Featuring Capillary Lobules

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To the Editor: With reference to the article entitled “the capillary lobule: a deceptively benign feature of postradiation angiosarcoma of the skin: report of 3 cases” by Di Tommaso and Rosai,1 we encountered an identical postradiation angiosarcoma of the skin characterized by capillary lobules. The patient was a 49-year-old woman who had a lumpectomy followed by radiation therapy for invasive ductal carcinoma of the left breast. Two and a half years later, she developed a 0.6 cm pink-purple lesion in the skin of the irradiated area, which was excised. Microscopically, the most striking feature was the presence of multiple round to oval capillary lobules throughout the dermis, suggestive of a hemangioma. The capillary lobules varied in size and were composed of compact vascular channels lined by slightly hyperchromatic endothelial cells (Fig. 1A). In addition to the capillary lobules, there were some areas with features typical of angiosarcoma, namely, anastomosing thin-wall vascular channels lined by plump hyperchromatic endothelial cells, intraluminal micropapillary formations, ill-formed vascular channels interposed between collagen bundles, and mitotic figures (Fig. 1B). We interpreted the lesion as an unusual angiosarcoma with features resembling hemangioma. A simple mastectomy was performed and revealed a 1.5 cm tumor with identical histopathologic features. The tumor was present 0.3 mm from the closest margin and 1 mm from the closest margin in a reexcision specimen. Six months later, the patient had a recurrent lesion in the same area with the same morphology. It was widely excised with negative margins. The patient is alive with no evidence of recurrence or metastasis 4 months later.FIGURE 1.: The tumor was mainly composed of round to oval capillary lobules scattered in the dermis, mimicking a hemangioma (A). However, some areas showed the typical features of angiosarcoma (B).In summary, the presence of capillary lobules in a postradiation angiosarcoma of the skin may present a diagnostic pitfall as it can readily be mistaken for a benign lesion. We agree with Di Tommaso and Rosai who state that “the detection of capillary lobules in irradiated skin ought to be regarded with great suspicion, and other morphologic signs suggestive of angiosarcoma should be sought in the specimen.” Zhenqiang Gao, MD, PhD Sheng Chen, MD, PhD Department of Pathology, Albert Einstein College of Medicine Long Island Jewish Medical Center, 270-05 76th Avenue New Hyde Park, NY