Rapid growth of an orbital hemangiopericytoma with atypical histopathological findings
A 45-year-old man presented with a palpable mass in the medial aspect of the right lower lid (). The patient had noticed a rapid growth of the lesion during the previous 2 months. The clinical examination revealed a firm mass, with smooth edges, without pain, tenderness, or pulsation. Given that the mass was superficial, the surgical approach was an anterior right orbitotomy, with complete excision of the tumor mass. Macroscopic examination of the specimen revealed an oval white rubbery mass measuring 11 × 9 × 7 mm. The mass was sectioned along its largest diameter and sent for processing. The interior of the lesion was solid, white, and homogeneous, without calcifications, cystic spaces, or hemorrhages. Hematoxylin and eosin sections showed a tumor with a lobular pattern composed of highly cellular areas separated by dense fibrous tissue. The mass was pseudoencapsulated, and the margins were free. Under high magnification, the lobules were predominantly vascular, with the presence of small and large vessels lined by normal endothelium, in a pattern resembling the staghorn pattern typical of HPC. There were no areas of necrosis or hemorrhage. Immunohistochemistry was positive for vascular markers such as factor VIII, CD34, and Ulex (). D2-40, epithelial membrane antigen, S-100, and glial fibrillary acidic protein were all negative, excluding other differential diagnoses. KI-67 staining returned an average of six positive cells per field (40×). Despite the high proliferative index, the tumor lacked other criteria to be considered malignant. The diagnosis of a benign HPC of the eyelid was then established.