When Symptomatic Hypercalcaemia and Lymphadenopathy Mimic Malignancy: An Atypical Case of Elderly-Onset Sarcoidosis

Sarcoidosis is a multisystem granulomatous disorder most commonly affecting the lung parenchyma and lymph nodes. However, virtually any organ system may be involved, resulting in a broad spectrum of clinical manifestations. Despite being predominantly a disease of younger adults, sarcoidosis has been infrequently reported in individuals older than 65 years, resulting in a limited body of literature on elderly-onset disease. We describe the case of an 83-year-old woman who presented with severe symptomatic hypercalcaemia accompanied by fatigue and unintentional weight loss, raising suspicion for an underlying malignancy. Initial laboratory investigations revealed an elevated serum calcium level of 3.72 mmol/L and a suppressed parathyroid hormone (PTH) level of 0.76 pmol/L, consistent with PTH-independent hypercalcaemia, which prompted an extensive diagnostic evaluation for malignancy. Ultimately, lymph node biopsy demonstrated non-caseating granulomas, consistent with a diagnosis of sarcoidosis. This case underscores the importance of recognising elderly-onset sarcoidosis as a potential mimic of malignancy and maintaining a high index of suspicion to avoid diagnostic delay.