Paraneoplastic hypercalcemia in a canine patient with a mandibular salivary carcinoma

To describe a novel presentation of paraneoplastic hypercalcemia caused by a canine salivary carcinoma.

A 6-year-old intact male Husky with hypercalcemia and a spontaneous salivary carcinoma, stage III.

The dog presented with polyuria, polydipsia, and hypercalcemia. Physical examination revealed a 37 X 43-mm firm mass in the ventrolateral aspect of the right-hand side of the neck, caudal to the temporomandibular joint. Incisional biopsy was suspicious of metastatic carcinoma to the mandibular lymph node. A full-body CT scan found a large, heterogenous, contrast-enhancing mass on the right ventrolateral neck that appeared to be originating from either the mandibular lymph node or right mandibular salivary gland. Parathyroid hormone-related protein was considered within normal reference intervals, and both parathyroid glands appeared ultrasonographically normal.

The patient was treated with a marginal surgical excision of the mass, without immediate complications. Histopathology confirmed the presence of a salivary carcinoma with narrow margins of excision and invasion of the mandibular lymph node. Twenty-four hours after surgery, ionized calcium returned to normal reference values and clinical signs completely resolved.

Hypercalcemia is an urgent pathology with important systemic implications requiring prompt diagnosis and intervention. In this case report, we identify the first salivary carcinoma associated with a paraneoplastic hypercalcemia, including this pathology as a new differential diagnosis. The hypercalcemia resolved with marginal surgical excision, but interestingly the parathyroid hormone-related protein was not overexpressed, meaning that this neoplasia could mediate hypercalcemia by another pathophysiological mechanism.