ECTOPIC PARATHYROID HORMONE SECRETION BY A PENILE SQUAMOUS CELL CARCINOMA

ABSTRACT Objective: Ectopic paraneoplastic secretion of parathyroid hormone (PTH) is rare, with only 25 cases previously reported in the literature, including only 2 attributed to squamous cell carcinoma. The recent presentation of such a patient and subsequent review of the literature has alerted us to the need for clinicians to consider such an etiology in patients presenting with humeral hypercalcemia of malignancy. Methods: Significant hypercalcemia occurred in a 48-year-old male with metastatic squamous cell carcinoma of the penis. The patient had hypercalcemia, elevated PTH, and normal PTH-related protein (PTHrp), without evidence of tumoral skeletal involvement. Comorbid primary hyperparathyroidism was suspected, but ultrasound and sestamibi scans of the neck were negative, raising the possibility of ectopic PTH production. This was confirmed by computed tomography–guided needle biopsy of a thigh metastatic lesion showing positive histochemical staining for PTH-specific antibodies and markedly elev...