Oral Hobnail Hemangioma of the Maxillary Labial Mucosa: Clinicopathologic Findings of a Rare Case.

Oral hobnail hemangioma is an exceptionally rare benign vascular lesion of the oral cavity. A 57-year-old edentulous woman presented for evaluation of discomfort associated with her existing prosthesis, and intraoral examination revealed a bluish-purple, smooth-surfaced, asymptomatic nodular lesion located in the anterior maxillary labial mucosa. Clinically, vascular malformation and hemangioma were considered in the differential diagnosis. Histopathological examination revealed dilated superficial vascular channels within the lamina propria, some of which contained erythrocytes, together with characteristic hobnail endothelial cell morphology in the superficial aspect of the lesion. Immunohistochemical analysis demonstrated CD34 positivity and HHV-8 negativity. Based on the clinical, histopathological, and immunohistochemical findings, a diagnosis of oral hobnail hemangioma was established. Accurate recognition of this rare entity is important because of its clinical and histopathological overlap with other benign, intermediate-grade, and malignant vascular proliferations, particularly Kaposi sarcoma and hemangioendothelioma variants.