Targetoid hemosiderotic hemangioma (hobnail hemangioma): typical clinical and histological presentation

Abstract

To the editor: Targetoid hemosiderotic hemangioma (THH), also known as Hobnail Hemangioma (HH) is characterized by a violaceous to brown targetoid lesion. The classic histological presentation of THH is that of ectatic vascular lumina mainly in the superficial and mid-dermis lined by a single layer of endothelial cells with hobnail appearance. We report here a case of THH in China with distinctive clinical features. A 71-year-old woman presented with a seven-day history of a solitary lesion on her abdominal wall. This initial lesion was a red and asymptomatic papule, surrounded by a violaceous area that gradually expanded peripherally and developed a bruiselike rim. The patient denied a history of previous trauma to the area. Examination revealed on the abdominal wall there was a 1.5 cm×1 cm firm red papule with a surrounding pale area and peripheral ecchymotic halo, resulting in a targetoid appearance (Figure 1A).Figure 1.: The clinical manifestation and pathologic findings of the patient. A: A red/purple targetoid lesion on the abdomen. B: Histology of a papular lesion showing dilated vessels filled with a large number of erythrocytes in the superficial and mid-dermis. a single layer of hobnail endothelial cells lining by vascular lumina were found to protrude into the lumen of the vessels and intraluminal papillary projections are also obviously seen (Hematoxylin-eosin staining, original magnification×400).Histology of the central papule revealed that in the upper and mid-dermis, there was a proliferation of dilated vascular lumens mostly filled with a large number of congested erythrocytes and a mild infiltration of inflammatory cells. Under higher magnification, a single layer of hobnail endothelial cells lining by vascular lumina were found to protrude into the lumen of the vessels and intraluminal papillary projections are also obviously seen (Figure 1B). THH is a rare benign vascular neoplasm, which was first described by Santa Cruz and Aronburg in 1988.1 Clinically THH appears as an asymptomatic small, solitary, red, purple, and/or brown papule that is typically encircled by a pale area and peripheral ecchymotic ring giving a targetoid appearance. Over time, the ecchymotic rim expands peripherally and ultimately disappears, leaving the central papule. The ring is, however, not a constant feature.2 The main histopathological feature of THH is a dermal vascular proliferation with biphasic growth patterns. In the papillary dermis, the ectatic vascular spaces are often lined with a single layer of prominent plump endothelial cells protruding into the lumen of the vessels. There are occasional intraluminal papillary projections. The histopathologic differential diagnosis of THH includes patch stage Kaposi's sarcoma and retiform hemangioendothelioma (RHE).3 The etiology of THH is unknown, one well-accepted mechanism is that of THH developing from trauma to a pre-existing hemangioma. Some patients with THH have been reported in whom the lesions changed periodically during menstruation, but immunohistochemical staining failed to demonstrate either estrogen or progesterone receptors in these cases.4 Trindade claimed that THH is better considered as a lymphatic malformation but not a lymphatic neoplasm on the basis of the WT1 negativity.5 Our old patient developed a typical purple targetoid lesion for a short time. The histopathology was characterized by a single layer of hobnail endothelial cells and intraluminal papillary projections. She denied a history of previous trauma. Min YANG Jian-min CHANG Department of Dermatology, Beijing Hospital, Beijing 100730, China (Yang M and Chang JM)