Superficial hemosiderotic lymphovascular malformation (hobnail hemangioma): a report of six cases.

Hobnail hemangioma (HH), initially termed targetoid hemosiderotic hemangioma, is a rare, often solitary lesion classically characterized by a central brown or violaceous papulonodule surrounded at times by an ecchymotic halo. This lesion is typically found on the trunk or limbs of children or young to middle-aged adults. Numerous case reports have found HHs to have a reproducible histologic appearance. Although the exact histogenesis of these lesions is unknown, multiple recent immunohistochemical studies suggest a lymphatic origin of these lesions. We present six cases of children with HHs with classic histology but with variability in their clinical appearance. Because the clinical presence of a targetoid halo is inconsistent and the hobnail phenomenon is not specific, we favor the designation of superficial hemosiderotic lymphovascular malformation instead of HH or targetoid hemosiderotic hemangioma as a more unifying term for this rare clinical entity. By eliminating confounding terminologies (in this case, incorporation of "hemangioma" in the name of this entity), we also hope to encourage a swifter change in practice to move away from erroneous diagnostic considerations.