Paraneoplastic hypercalcemia in a canine patient with a mandibular salivary carcinoma.

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

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

CLINICAL PRESENTATION, PROGRESSION, AND PROCEDURES: 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.

TREATMENT AND OUTCOME: 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.

CLINICAL RELEVANCE: 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.