Hobnail (Targetoid Hemosiderotic) Hemangioma
David Cassarino, MD, PhD
Key Facts
Terminology
Targetoid hemosiderotic hemangioma
Benign vascular proliferation, typically wedge-shaped, showing intravascular papillae and hobnailed endothelial cells
Etiology/Pathogenesis
Postulated to represent traumatized lymphangioma or hemangioma
Clinical Issues
Typically presents on lower extremities; also may occur on upper extremities, rarely in oral cavity
Microscopic Pathology
Superficial vessels are dilated and thin-walled
Deeper vessels are progressively smaller
Vessels are lined by small, bland-appearing endothelial cells with hobnail appearance
 Low-magnification view of a hobnail hemangioma demonstrates superficial dilated vascular spaces  in the papillary dermis with deeper small blood vessels and stromal hemosiderin deposits  . |
 Higher power examination shows a hobnail hemangioma with superficial dilated vessels lined by small endothelial cells protruding into the lumina  and showing nuclear hyperchromasia. |
TERMINOLOGY
Abbreviations
Hobnail hemangioma (HH)
Synonyms
Targetoid hemosiderotic hemangioma (clinical term)
Definitions
Benign vascular proliferation, typically wedge-shaped, showing intravascular papillae and hobnailed endothelial cells
ETIOLOGY/PATHOGENESIS
Unknown
Trauma has been implicated in some cases
Postulated to represent traumatized lymphangioma or hemangioma
