Anti-interferon-γ autoantibody-associated disseminated Mycobacterium abscessus infection mimicking parotid cancer with multiple metastases

RATIONALE Among the nontuberculous mycobacteria, Mycobacterium abscessus is a common cause of skin, soft tissue, and bone infections. However, disseminated M. abscessus infection that mimics cancer metastasis with an underlying relatively immunocompetent condition has rarely been reported. PATIENT CONCERNS A nonsmoking 73-year-old man with an underlying relatively immunocompetent condition reported a 2-month history of a mass in the region of his right parotid gland that had been steadily increasing in size. DIAGNOSES The head and neck computed tomography showed an avidly enhancing tumor with central necrosis in the right parotid region and lymphadenopathy bilaterally at neck levels II-V (<6 cm) with a necrotic core. The radiologist and otolaryngologist both suspected a diagnosis of right parotid gland cancer with metastasis. INTERVENTIONS The necrotic tissue was removed surgically, and Mycobacterium culture showed M. abscessus. We collected a blood sample and detected anti-interferon-γ autoantibody. OUTCOMES After 6 months of anti-M. abscessus treatment, physical examination showed remission of the parotid tumor, and axillary and supraclavicular lymphadenopathy. LESSONS We report a case of disseminated M. abscessus infection, which involved parotid glands with multiple lymphadenopathies in a person with an underlying relatively immunocompetent condition. Possible underlying mechanisms such as anti-interferon-γ autoantibody-associated immunodeficiency should be considered in a patient with disseminated M. abscessus infection without a known immunocompromised condition.