An Unusual Case of Isolated Cryptococcal Osteomyelitis of Mastoid: An Enigma!

Abstract Cryptococcosis is a disseminated fungal infection commonly affecting the lungs and the central nervous system in immunocompromised patients. Herein we report a rare case of isolated mastoid osteomyelitis due to Cryptococcus neoformans which was initially not recognized due to its uncommon presentation akin to a Betzold’s abscess. A 61-year-old male presented with complaints of left ear discharge for a 1-month duration associated with a swelling in the left side of the neck for which he underwent incision and drainage without any significant improvement. a contrast-enhanced computed tomography (CT) scan revealed extensive erosion of the left mastoid cavity with a collection. Intraoperatively, red friable granulation tissue was seen within the antrum, histopathology of which revealed capsulated yeast forms. The patient underwent left canal wall down mastoidectomy along with antifungal treatment. Bone involvement is rare in patients with cryptococcal infection with vertebrae being the most common site of cryptococcal osteomyelitis. The clinical presentation is nonspecific and can pose a diagnostic dilemma, as the condition can mimic both Betzold’s abscess as well as malignancy. CT findings and the use of specific fungal stains in histopathology will aid in diagnosing this condition. The purpose of this case report is to establish the first case of isolated cryptococcal mastoid osteomyelitis in the database of fungal osteomyelitis. The confirmation of fungal osteomyelitis should be based on histopathological examination. The possibility of fungal osteomyelitis should be borne in mind in any case of insidiously increasing mass with unclear etiology so that prompt antifungal therapy with surgical debridement is initiated.