Track

Case Reports

Abstract

Immune checkpoint inhibitor (ICI)-associated sarcoidosis or sarcoid-like reaction (SLR) is a rare yet increasingly recognized immune-related adverse effect. We report the case of an 81-year-old female with Stage IIIC desmoplastic melanoma of the left eyebrow (Breslow depth 4.3 mm with in-transit metastases, pT4a pN1 cM0) who presented with multiple asymptomatic subcutaneous nodules on the lower trunk and legs. She had been undergoing immunotherapy with pembrolizumab for three months and developed the nodules over the preceding six weeks. Routine histopathology demonstrated subcutaneous sarcoidal granulomas with mixed inflammation, without evidence of metastatic disease. After discarding infectious and exogenous etiologies, a diagnosis of pembrolizumab-induced sarcoidosis was achieved. Nuclear imaging demonstrated innumerable generalized hypermetabolic subcutaneous nodules and new asymptomatic, hypermetabolic hilar, mediastinal, and interlobar lymphadenopathy. Her disease had progressed locally despite four cycles of pembrolizumab, and treatment was subsequently changed to combination ipilimumab and nivolumab. The patient was started on hydroxychloroquine, with stable nodules 1 month later. ICI-induced SLR occurs most commonly with therapy for metastatic melanoma and arises during the first few months of treatment, often alongside pulmonary findings. Although most patients recover regardless of treatment, it remains unclear whether SLR confers a prognostic benefit. Severe or multiorgan involvement may require discontinuation of immunotherapy and initiation of immunosuppression, while limited or asymptomatic disease should not interrupt effective oncologic therapy. The clinical presentation of subcutaneous nodules can raise concern for metastatic disease that may impact treatment decisions. Therefore, skin biopsy and accurate histopathologic diagnosis are crucial for appropriate management.