(A502) A Novel Case of Oropharyngeal Squamous Cell Carcinoma with Hypercalcemia of Malignancy

Introduction: Humoral hypercalcemia of malignancy (HHM) is a paraneoplastic syndrome most often characterized by ectopic production of parathyroid hormone related-protein (PTHrP), leading to increased bone resorption and renal calcium reabsorption. While HHM has been sparsely documented with other head and neck squamous cell carcinomas (HNSCC), it has never been reported in oropharyngeal squamous cell carcinoma (OPSCC). We present the first documented case of HHM occurring in a patient with OPSCC.

Methods: A case report and literature review was performed.

Results: A 65-year-old man with a history of stage IV p16-positive OPSCC presented to the emergency department with progressive dysphagia, left jaw pain, and facial swelling 11 months after completion of chemoradiotherapy along with a large mass in the oropharynx consisting with recurrent disease. A computed tomography demonstrated extensive localized disease and laboratory evaluation revealed hypercalcemia of 12.3 mg/dL, hypophosphatemia of 2.1 mg/dL, a normal PTH of 10.7 and a normal EKG. Patient ultimately needed tracheostomy and PEG tube placement. The patient was readmitted 1 month later with constipation, myalgias, and polyuria. Laboratory evaluation revealed hypercalcemia of 16.9 mg/dL and an elevated PTHrP of 3.2. A diagnosis of HHM was made, and despite aggressive treatment with intravenous fluids, zoledronic acid, and calcitonin, the patient exhibited refractory hypercalcemia up to 14.4 mg/dL. As of last visitation, the patient is undergoing treatment for acute kidney injury secondary to dehydration and hypercalcemia and awaiting further oncologic testing.

Conclusions: This case represents the first documented case of humoral hypercalcemia of malignancy in oropharyngeal squamous cell carcinoma. This novel presentation establishes a unique example in the possible paraneoplastic manifestations of OPSCC. Further investigation is warranted to determine its prevalence and significance in this patient population.