Schwannoma involving the sphenoid sinus

A 68-year-old man presented with progressive headaches. Physical and neurological examinations revealed no abnormalities. CT demonstrated a heterogeneously enhanced mass occupying the lateral aspect of the left sphenoid sinus (Fig. 1A; arrowheads), eroding both the sinus wall and the floor of the middle cranial fossa (Fig. 1B; arrow). MRI delineated no obvious tumor involvement of the middle cranial fossa (Fig. 1C). The lesion was avascular on cerebral angiography. A left zygomatic extradural subtemporal approach through a straight pre-auricular skin incision allowed total resection of an elastic hard tumor containing xanthochromic fluid. The tumor originated from the maxillary division of the trigeminal nerve at the eroded foramen rotundum, but the major part of the tumor involved the sphenoid sinus, destroying the lateral wall. Dural invasion was not seen. Postoperatively, he recovered well with mild paresthesia in the maxillary nerve. Histopathological examination confirmed the diagnosis of schwannoma (Fig. 1D). Trigeminal neurinoma is known to extend extracranially along the three divisions of the nerve, occasionally manifesting as orbital, nasomaxillary, or infratemporal masses [4, 5]. Very rarely, however, main involvement of the sphenoid sinus occurs [1–3], where mucocele or bone tumor has a predilection for chronic expansion. The present case offers a reminder of the considerable variability displayed by trigeminal neurinoma.