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JAMA Clinical Challenge
May 12, 2023

Black Tongue Discoloration

Author Affiliations
  • 1Department of Emergency and General Medicine, Tokyo Metropolitan Tama Medical Center, Tokyo, Japan
JAMA. 2023;329(21):1875-1876. doi:10.1001/jama.2023.5894

An 80-year-old man presented to the emergency department with a 5-day history of fever and right shoulder pain. His temperature was 37.9 °C (100.2 °F); heart rate, 74/min; and blood pressure, 90/49 mm Hg. He had tenderness to palpation and decreased range of motion of his right shoulder. Laboratory testing showed a white blood cell count of 9.6 ×  109/L (reference, 4.0-9.0 × 109/L); C-reactive protein level, 35.6 mg/dL (reference, <0.3 mg/dL), and creatine kinase level, 1036 U/L (17.30 μkat/L) (reference, 60-270 U/L [1.00-4.51 μkat/L]). Magnetic resonance imaging revealed an effusion and synovial thickening with enhancement in the right shoulder joint and inflammation in the right subscapularis muscle. Gram stain of the synovial fluid revealed gram-positive cocci in clusters. Intravenous cefazolin therapy was initiated, and he underwent right shoulder joint arthroscopic irrigation, synovectomy, and surgical drainage for subscapularis pyomyositis. Blood and synovial fluid cultures grew methicillin-susceptible Staphylococcus aureus, and intravenous cefazolin was continued. One week after hospitalization, the patient developed asymptomatic black discoloration of the dorsal surface of his tongue (Figure). He reported no prior lingual discoloration and did not smoke cigarettes, use chewing tobacco or illicit drugs, or drink alcohol.

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