Differential diagnosis of idiopathic inflammatory trigeminal sensory neuropathy from neuroma with a biopsy: case report.

OBJECTIVE AND IMPORTANCE: Idiopathic inflammatory trigeminal sensory neuropathy (IITSN) is a disorder with the dominant clinical features of trigeminal sensory disturbance; this idiopathic condition follows a benign course in most cases. Recent reports have shown that transient abnormalities, which may mimic those of trigeminal neuromas, can be observed in magnetic resonance imaging scans. Presented here is a case of IITSN that was diagnosed, with cytological and histopathological verification, during the active inflammatory phase of the disease (the first such attempt, to our knowledge). CLINICAL PRESENTATION: A 20-year-old female patient was referred to our hospital with a 2-month history of numbness of the left side of her face, headache, and hemifacial pain attacks. Cranial magnetic resonance imaging scans revealed a mass above and below the foramen ovale, extending into the cavernous sinus. INTERVENTION: A percutaneous biopsy procedure through the foramen ovale was performed; the pathological examination revealed lymphocytes, macrophages, and endothelial cells but no evidence of neoplastic cells. A few days later, the patient was surgically treated using a cranial base approach, the gasserian ganglion was exposed, and the lesion was removed. Pathological examination of the specimens revealed inflammatory changes and fibrosis of the nerve fibers and ganglion cells. Disruption of the myelin around the nerve bundles was detected. Therefore, IITSN was pathologically confirmed during the early stage of the disease. During 3 months of follow-up monitoring, the patient experienced no serious clinical problems. CONCLUSION: IITSN should be suspected in cases of tumors involving the cavernous sinus, and a percutaneous biopsy through the foramen ovale should be performed as part of the differential diagnosis in such cases. This procedure might obviate unnecessary aggressive surgery. In the current case, no neoplastic cells were observed during the examination; only lymphocytes, macrophages, and endothelial cells were observed, on a background of erythrocytes. Lymphocyte-dominant inflammatory infiltration, fibrotic changes, and demyelinization are cardinal histopathological findings observed during the active phase of IITSN.