Asymptomatic hypercalcemia, caused by sarcoid-like granulomatosis, induced by checkpoint inhibition.

Objectives: To illustrate the diagnostic challenges, as well as the importance of early recognition of rare immunotherapy-induced complications, presenting a case and literature of sarcoid-like granulomatous reaction.

Methods: This report presents a case of asymptomatic hypercalcemia, revealing a sarcoid-like granulomatosis in a patient with metastatic melanoma, treated with an immune checkpoint inhibitor (ICI). In the discussion, an overview of the existing literature is provided through a PubMed search.

Results: Thorough investigations are essential to rule out disease progression and other possible explanations. Ultimately, biopsy with extensive staining led to the diagnosis of sarcoid-like granulomatosis. As there is no consensus in treatment, we suggest a case-by-case assessment, if possible by discussion within the multidisciplinary treatment team, to decide discontinuation of the causal ICI-therapy or the use of systemic steroids as supportive therapy.

Conclusion: This case demonstrates the importance of a broad differential diagnosis when identifying an asymptomatic hypercalcemia as well as new CT-graphic lesions, since the diagnosis of sarcoid-like granulomatosis can avoid not only unnecessary changes in treatment plans, avoiding toxicity, but also be a sign of good prognosis.