Lymphoma in Meckel cave mimicking trigeminal schwannoma - analysis of misdiagnosis causes and insights into imaging: Case report.

[RATIONALE] Central nervous system lymphoma typically arises in the deep cerebral regions, while occurrence in the Meckel cave at the skull base is exceedingly rare, with fewer than 1 hundred cases reported globally. Lesions in this area are often misdiagnosed as trigeminal schwannomas or meningiomas. This report aims to enhance clinical recognition of this rare entity by presenting a meticulously analyzed case that was initially misdiagnosed as a trigeminal schwannoma due to overlapping radiological features. Through detailed clinicopathological correlation, we seek to identify key diagnostic indicators that may facilitate earlier accurate diagnosis and prevent unnecessary surgical interventions.

[PATIENT CONCERNS] A 60-year-old female presented with a 1-month history of paroxysmal electric shock-like pain in the right ala nasi, cheek, and upper lip. Symptoms occurred multiple times daily without identifiable triggers and were not accompanied by other neurological deficits. The patient had no history of immunodeficiency-related conditions.

[DIAGNOSES] Imaging revealed a space-occupying lesion in the right Meckel cave, demonstrating a "dumbbell-shaped" transcompartmental growth pattern along the trigeminal nerve pathway. The lesion was misdiagnosed preoperatively as a trigeminal schwannoma. Postoperative pathology confirmed diffuse large B-cell lymphoma, with immunohistochemistry indicating a germinal center subtype.

[INTERVENTIONS] The patient underwent surgical resection to relieve nerve compression. Due to the preoperative misdiagnosis, cerebrospinal fluid cytology and comprehensive systemic staging were not performed.

[OUTCOMES] Facial pain resolved postoperatively. However, the patient continued to experience residual facial numbness postoperatively. Given the confirmed lymphoma diagnosis, the patient is scheduled to receive methotrexate-based combination chemotherapy following the postoperative recovery period.

[LESSONS] The "perineural growth" pattern and "dumbbell" morphology of this Meckel cave lymphoma were highly deceptive and directly led to misdiagnosis. Lymphoma should be critically included in the differential diagnosis for Meckel cave lesions presenting with rapid progression (<6 months), schwannoma-like imaging features, and absence of prominent T2 hyperintensity. Preoperative cerebrospinal fluid analysis or targeted biopsy can prevent unnecessary surgical interventions and ensure timely administration of standardized chemotherapy.