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Intravascular papillary endothelial hyperplasia in the maxillary sinus. A benign lesion that may be mistaken for angiosarcoma.

Intravascular papillary endothelial hyperplasia is a vascular benign lesion bearing some similarities to malignant angiosarcoma. To the best of our knowledge, it has never been described within the paranasal sinuses. A case of such a lesion within the maxillary sinus appearing in a 17-year-old boy who presented with unilateral facial pains and proptosis is reported. The lesion, despite its benign nature, extended to the ethmoidal cells and nasal cavity and pressed the floor of the orbit. Clinically and histopathologically it may be mistaken for an angiosarcoma. An awareness of this similarity and the features in which it differs from angiosarcoma will prevent incorrect diagnosis and inappropriate treatment.