Congenital and multiple hobnail hemangiomas.

Hobnail hemangioma (targetoid hemosiderotic hemangioma) is a vascular tumor affecting the limbs or trunk. Characteristically, the lesion has a "targetoid" clinical feature and dilated vascular spaces lined by hobnail endothelial cells at histologic examination. The age of onset is widely variable, form 5~67 years, typically occurring in young or middle-aged persons. It is usually apparent as a small solitary lesion. However, multiple lesions are identified sometimes. Herein, we report two cases of hobnail hemangioma in 7-year-old and 15-year-old males. Of note, the former case had a congenital lesion and the latter, multiple acquired lesions, which are both rare atypical presentations of the disease.