Hyperostotic Esthesioneuroblastoma: Rare Variant and Fibrous Dysplasia Mimicker

A 65-year-old male presented with a 3-year history of orbital symptoms. An imaging-based diagnosis of fibrous dysplasia involving the skull base was made at another institution. CT showed a diffuse sinonasal mass and ground-glass appearance of the bones of the anterior skull base with bony defects and mucocele formation. MRI demonstrated an accompanying intracranial and orbital rind of soft tissue mass along the hyperostotic bones. FDG-PET showed corresponding intense hypermetabolism. Small cysts were observed at the tumor-brain interface. Biopsy revealed esthesioneuroblastoma with bone infiltration that is compatible with the hyperostotic variant of esthesioneuroblastoma. There are a few cases of hyperostotic esthesioneuroblastoma reported in the literature.