Introduction::
Primary hyperparathyroidism (PHPT) results from an excess secretion of parathyroid hormone (PTH), primarily due to parathyroid adenomas. These adenomas are more prevalent in women and, although rare, can develop into giant adenomas. One infrequent but notable complication of giant adenomas is parathyroid apoplexy. The aim of this manuscript is to describe the case of a Peruvian female patient diagnosed with PHPT secondary to a giant parathyroid adenoma, whose surgical treatment confirmed its apoplexy.

Case report::
A 42-year-old Peruvian woman with hypertension and stage IV chronic kidney disease presented with a non-productive cough, dysphonia, and acute chest pain, revealing a mediastinal tumor on imaging. Physical examination showed no cervicaltumors, and biochemicaltests revealed elevated levels oftotal calcium and intact PTH, while serum phosphorus and calcitonin levels were normal. Imaging elucidated a parathyroid adenoma with mediastinal extension. Surgical intervention involved right parathyroidectomy, unveiling a 6 × 6 cm tumor with cystic and hemorrhagic degeneration, confirming the diagnosis of parathyroid apoplexy from a giant adenoma.

Conclusions::
Giant parathyroid adenoma should be considered in patients presenting with a mediastinal mass and hypercalcemia. This condition can be complicated by parathyroid apoplexy in the context of PHPT. Timely imaging and surgical intervention are crucial for achieving optimal outcomes, with diagnosis confirmed through histopathology.