Intravascular papillary endothelial hyperplasia in the mandible: a case report

Intravascular papillary endothelial hyperplasia (IPEH) is histopathologically characterized by papillary proliferation of vascular endothelial cells. IPEH in the mandible is very rare, such that only four affected patients have been described in the English-language medical literature. Thus, there is a poor understanding of the pathogenesis and clinical features of IPEH in the mandible. This case report describes a patient with IPEH in the mandible who had a history of repeated trauma involving the mandible due to boxing-related and baseball-related injuries. Imaging examinations had diagnostic limitations, in that they showed a multilocular radiolucency suggestive of a simple bone cyst of the mandible, whereas intraoperative findings revealed a fluid-free unicystic cavity lined by a thin red membrane. Thus, histopathologic examinations were necessary for definitive diagnosis. The specimen demonstrated a spongy structure consisting of many small papillary fibrous tissues, lined by a typical monolayer endothelium that expressed CD34, but did not express D2-40 or AE1/AE3. Moreover, the Ki-67 labeling index was <1%. Thus, the lesion was identified as intraosseous IPEH in the mandible. Although the pathogenesis of IPEH has been controversial, our findings in this case suggest that pathogenesis of IPEH may be related to a history of trauma.