Cutaneous Lesions, Severe Hypercalcemia and Acute Kidney Injury Revealing Sarcoidosis: A Case Report with Atypical Histology and Corticosteroid-Induced Diabetes

A 55-year-old woman with a 4-year history of mediastinal adenopathy of unknown etiology presented with progressive cutaneous lesions, severe hypercalcemia (120 mg/L), and acute kidney injury (serum creatinine 70 mg/L). Angiotensin-converting enzyme levels were markedly elevated (98 U/L). Kidney biopsy revealed acute tubulointerstitial nephritis without granulomas. The diagnosis of sarcoidosis was established, and prompt corticosteroid therapy led to spectacular improvement of renal function, normalization of serum calcium, and complete resolution of cutaneous lesions. Corticosteroid-induced hyperglycemia required transient insulin therapy. This case illustrates that the absence of granulomas on kidney biopsy does not exclude sarcoidosis, and that early recognition can prevent progression to chronic kidney disease.