Silva, Ana Bento daTorres, Rita PinheiroLourenço, Maria HelenaCabral, CatarinaReis, RitaCunha-Branco, JaimeGonçalves, Maria João2023-08-302023-08-302022-05Silva AB, Torres RP, Lourenço MH, Cabral C, Reis R, Gonçalves MJ, et al. An atypical case of focal myositis. Rheumatology. 2022;61(6):e158-9.http://hdl.handle.net/10400.21/16431A 64-year-old woman presented with a 10-day history of painful progressive bilateral temporal and right retroauricular region tumefaction, dysphonia, and a body temperature of 37.5°C. She had been previously prescribed antibiotics assuming an oral infection, with no benefit. She had no other complaints and her past medical history and clinical exam were otherwise unremarkable. Her labs revealed high levels of CRP (11.7 mg/dl), ESR (52 mm/h), creatine kinase (CK 623 U/l), myoglobin (83 U/l), aspartate transaminase (56 U/l) and alanine transaminase (69 U/l). Serologies were negative for Treponema pallidum, human immunodeficiency, hepatitis B and C, and Epstein–Barr viruses; blood cultures and immunological study, including anti-nuclear antibodies and antibodies associated with inflammatory myopathies, were negative. A facial MRI revealed thickening and T2/FLAIR hypersignal of the temporal, masseter, and pterygoid muscles with signal intensification after gadolinium injection, suggesting myositis. A temporal muscle biopsy showed marked lymphocyte infiltration (predominantly lymphocyte T CD3), as well as the marking of multiple fibres with major histocompatibility complex class I products, which supported the diagnosis. Prednisolone 0.5 mg/kg/day (30 mg) was started, with marked clinical improvement and normalization of CRP, ESR, and CK.engMasticatory musclesMyositisFocal myositisjournal article10.1093/rheumatology/keab574