Targetoid hemosiderotic hemangioma (THH), also known as targetoid hemosiderotic lymphatic malformation (THLM), is a benign lesion characterized clinically by a solitary central, brown-violaceous papule with or without a surrounding thin, pale area and ring of ecchymosis, creating a targetoid appearance. While THH was once thought to be of vascular origin, immunohistochemical data support its lymphatic origin, as THH stains positively for lymphatic markers including D2-40. Additionally, immunohistochemical studies have shown a pattern that is more consistent with a vascular malformation than a neoplasm, as implied by the term "hemangioma."
THH is a rare finding that tends to appear in young or middle-aged individuals. It has a predilection for the trunk and/or extremities. No definitive risk factors exist, although it is speculated that trauma may play a role in the development and flaring of these lesions.
ICD10CM: D18.01 – Hemangioma of skin and subcutaneous tissue