Morphological features of immune-related cutaneous adverse events associated with anti-PD-1/PD-L1 cancer immunotherapy

Objective. To study the morphological patterns of immune-related cutaneous lesions (irCLs) that occur during antitumor immunotherapy in cancer patients. Material and methods. The study included 48 patients with the following nosology: malignant neoplasms of the skin and soft tissues — 20 patients (41.7%), malignant neoplasms of the genitourinary system — 13 (27%), malignant neoplasms of the lungs and bronchi — 9 (18.8%), malignant neoplasms of the upper respiratory tract — 5 (10.4%), malignant neoplasms of the gastrointestinal tract — 1 (2.1%), with immune-mediated skin lesions during treatment with pembrolizumab — 25 (52.1%), nivolumab — 18 (37.5%), prolgolimab — 4 (8.3%), avelumab — 1 (2.1%). Results. Among the irCLs in the study cohort, lichenoid — 14 (29.2%) cases and psoriasiform — 11 cases (22.9%) were predominant, while other morphological variants were significantly less common. IrCL morphologically mimic classic dermatoses, but have distinctive features indicating their drug-induced, immune-related nature. Conclusion. The study demonstrated that irCLs are clinically significant complications of PD-1/PD-L1 inhibitor therapy. Histological analysis confirmed their immunoinflammatory nature and revealed characteristic morphological changes, emphasizing the importance of routine skin biopsies for optimal patient management.