18 July 2026
: Case report 
A 79-Year-Old Woman With Stage IIIB Lung Squamous Cell Carcinoma Presenting With Late-Onset Durvalumab‑Associated Myocarditis Requiring Differentiation From Pericardial Invasion
Unusual clinical course, Challenging differential diagnosis, Unusual or unexpected effect of treatment, Diagnostic / therapeutic accidents, Adverse events of drug therapy, Educational Purpose (only if useful for a systematic review or synthesis)
Norio Kodaka ABCDEF 1, Fumiyuki Hayashi BCE 2, Yuki Yokouchi BCE 3, Masahiro Yoshida BCE 4, Hiroto Matsuse ACDE 1*DOI: 10.12659/AJCR.953001
Am J Case Rep 2026; 27:e953001
Figure 3 Myocardial biopsy demonstrating lymphocytic and macrophage infiltration without evidence of malignant cells, supporting the diagnosis of myocarditis and excluding myocardial invasion. (A) Hematoxylin–eosin staining and immunohistochemistry ((B) CD3, (C) CD20); original magnification ×200. Immunostaining revealed an inflammatory infiltrate predominantly composed of CD3-positive T cells. These cells were distributed within the myocardium, involving the subendocardial and myocardial fibers as well as the perivascular regions. CD20-positive B-cell infiltration was minimal. The findings were consistent with a T-cell–predominant lymphocytic infiltrate.