Case Summary
A 58-year-old man with melanoma treated with ipilimumab/nivolumab presented with pain, limited joint mobility, and proximal weakness without oculobulbar weakness, dyspnea, or rash. EMG demonstrated positive sharp waves, fibrillations, and myopathic units. Extremity MRI showed diffuse fascial and mild muscle enhancement consistent with fasciitis/mild myositis (Figure). Creatinine kinase was normal. PET-CT demonstrated diffusely fluorodeoxyglucose-avid lymph nodes and muscles; lymph node biopsy revealed granulomatous inflammation suggesting immune checkpoint inhibitor-related inflammatory reaction. Biceps biopsy demonstrated perifascicular atrophy (PA) and fascial/perimysial perivascular inflammation (Figure).
Perifascicular atrophy noted on H&E (A), ATPase (B), and nicotinamide adenine dinucleotide (C) stains (arrow) with fascial, perimysial, and perivascular inflammatory infiltrates on H&E (A, arrowhead) and acid phosphatase (D, E, arrowheads). Precontrast and postcontrast MRI of the lower extremities (F.a, F.b) and upper extremities (F.c, F.d) with fascial and muscle enhancement.
Histopathologic findings of immune checkpoint inhibitor-related myositis initially included necrosis, macrophagy, and endomysial inflammation. The spectrum has expanded to include perimysial perivascular inflammation and PA tendency.1,2
Study Funding
The authors report no targeted funding.
Disclosure
T.R. Fullam reports no disclosures relevant to the manuscript; N. McGraw reports no disclosures relevant to the manuscript; M. Grainger reports no disclosures relevant to the manuscript; S. Chandrashekhar reports no disclosures relevant to the manuscript; M.M. Dimachkie reports no disclosures relevant to the manuscript with full disclosures up to date on the AAN website. Go to Neurology.org/N for full disclosures.
Appendix Authors
Footnotes
Go to Neurology.org/N for full disclosures. Funding information and disclosures deemed relevant by the authors, if any, are provided at the end of the article.
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- © 2021 American Academy of Neurology
References
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