Case Report: Multiple skeletal lesions as the initial presentation of primary hyperparathyroidism: A case of parathyroid adenoma mimicking malignancy.

Background: Primary hyperparathyroidism (PHPT) is a relatively common endocrine disorder, although advanced skeletal manifestations mimicking metastatic malignancy are uncommon, characterized by autonomous oversecretion of parathyroid hormone. Case presentation: We report the case of a 67-year-old female who presented with cough and chest pain and was later found to have extensive osteolytic lesions initially suspected as malignant bone metastases. A multidisciplinary evaluation, including laboratory testing and advanced imaging, was performed. The evaluation revealed primary hyperparathyroidism due to a parathyroid adenoma. Surgical resection of the adenoma normalized serum calcium and parathyroid hormone levels, leading to marked symptomatic improvement. By the last follow-up, her pain had significantly improved, and parathyroid hormone levels had normalized. Conclusions: This case highlights the importance of considering endocrine etiologies when evaluating patients with atypical bone lesions, particularly in patients presenting with atypical respiratory symptoms and thoracic imaging findings that closely mimic primary lung malignancy with bone metastases.