Atypical Skull Base Osteomyelitis of the Clivus Mimicking a Malignant Lesion: A Case Report

Atypical skull base osteomyelitis (ASBO) is a rare disease, typically involving the basisphenoid and basiocciput. Diagnosis consists of clinical examination, imaging methods such as PET-CT scans and MRI, microbiological testing, and possibly native tissue samples. Long-term intravenous antibiotic therapy is the treatment of choice. Methods/Case Report: We present a case of ASBO of the clivus initially suspected to be a malignant lesion due to malignant melanoma in the patient's history. Several tissue biopsies were taken, and microbiological testing of native tissue biopsies in combination with PET-CT and MRI imaging led to the diagnosis of ASBO. The patient received long-term antibiotic therapy with meropenem and drastically improved in his overall health.

This case highlights the challenges encountered in the diagnosis and management of ASBO, especially with relevant possible differential diagnoses.