A Rare Case of Isolated Extrapulmonary Sarcoidosis With Renal Involvement Sans Pulmonary Findings: Diagnostic Challenges and Clinical Insights

The cause of sarcoidosis is unknown, and it affects multiple systems with granulomas. Lung lesions are typical, but extrapulmonary findings, especially lymphadenopathy, are present in a significant number of cases. Isolated renal involvement is rare. The presence of noncaseating granulomas on biopsy is a hallmark of sarcoidosis. We present the case of a 59-year-old male with recurrent renal stones who presented with renal failure. The initial diagnosis was challenging due to normal chest imaging and no pulmonary involvement. However, his delayed presentation of calcinosis cutis, an increase in angiotensin-converting enzyme (ACE) level, and the biopsy of the palm lesion with noncaseating granulomas helped us reach the diagnosis. He was started on prednisolone and achieved remission. The report also intends to show that patients with sarcoidosis can present without lung involvement, and physicians should consider sarcoidosis as their differential diagnosis for idiopathic hypercalcemia even if it has no lung or skin findings.