Benign giant pilomatricoma with associated hypercalcemia: a case report

The patient presented to the emergency department with nausea and vomiting with a large, rapidly growing soft tissue mass on her left shoulder diagnosed as a giant pilomatricoma. Pilomatricomas are tumours derived from hair follicles that are typically benign and rarely cause systemic symptoms. However, this patient exhibited hypercalcemia and elevated parathyroid hormone-related peptide (PTHrP) levels, suggesting PTHrP secretion by the tumour. Surgical resection normalized the patient's calcium and PTHrP levels. This case demonstrates that tumours such as pilomatricomas can rarely secrete PTHrP and cause hypercalcemia, a characteristic not typically associated with benign growths. It emphasizes the importance of considering benign tumours in the differential diagnosis of hypercalcemia.