Background: Cryptococcal osteomyelitis is a bone infection caused by cryptococcus. As an opportunistic infection, bone cryptococcosis usually occurs in patients with immunodeficiency diseases or in those undergoing immunosuppressive therapy and often displays characteristics of disseminated disease. Isolated cryptococcal osteomyelitis is extremely unusual in immunocompetent person. The pathogenic fungus often invades vertebrae, femur, tibia, rib, clavicle, pelvis, and humerus, but the ulna is a rare target.
Case summary: A 79-year-old woman complaining of chronic pain, skin ulceration and a sinus on her right forearm was admitted, and soon after was diagnosed with cryptococcal osteomyelitis in the right ulna. Unexpectedly, she was also found to have apparently normal immunity. After treatment with antifungal therapy combined with surgery debridement, the patient's osteomyelitis healed with a satisfactory outcome.
Conclusion: Although rare, cryptococcal osteomyelitis should be considered in the differential diagnosis of osteolytic lesions even in immunocompetent patients, and good outcomes can be expected if early definitive diagnosis and etiological treatment are established.
Keywords: Case report; Cryptococcus neoformans; Immunocompetence; Isolated lesions; Osteomyelitis; Ulna.
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