Osseous metaplasia within a canine insulinoma

Abstract

An 11-year-old male castrated mixed-breed dog was presented for exercise intolerance, tetraparesis, and persistent hypoglycemia. Abdominal ultrasound examination revealed 2 nodules within the right limb of the pancreas. Cytology from one nodule was consistent with a carcinoma of neuroendocrine origin, with a primary differential diagnosis of insulinoma. Histologic evaluation and immunohistochemistry for synaptophysin and insulin confirmed the diagnosis of insulinoma. Additionally, there was a solitary nodule of mineralized compact bone composing approximately 60% of the mass. To the authors' knowledge, this is the first report of osseous metaplasia within an insulinoma (islet cell carcinoma). Case PresentationAn 11-year-old male castrated mixed-breed dog was presented to the Ohio State University Veterinary Medical Center (OSUVMC) for evaluation of exercise intolerance and tetraparesis for several weeks' duration, as well as persistent hypoglycemia. Serum chemistry performed at OSUVMC showed sustained marked hypoglycemia (36 mg/dL; reference interval [RI] 77-126 mg/dL), mild hypokalemia (3.92 mEq/L; RI 4.2-5.4 mEq/L), and mildly elevated total serum ALP activity (148 IU/L; RI 15-120 IU/L]) with significantly increased corticosteroid-induced ALP isoenzyme activity (138 IU/L; RI 0-6 IU/L). An abdominal ultrasound examination identified 2 hypoechoic nodular structures measuring 2.9 9 1.9 cm (cranial nodule) and 3.3 9 1.4 cm (caudal nodule) in the right limb of the pancreas. The echogenicity of these nodules was heterogenous with focal hyperechoic shadowing regions. A fine-needle aspirate of one pancreatic nodule revealed many variably sized clusters of large, round to polygonal shaped cells within a background of blood and numerous bare nuclei (Figure 1). Neoplastic cells displayed mild-to-moderate anisocytosis and anisokaryosis. Nuclei were round to oval, centrally placed, and had a fine chromatin structure with 1-3 prominent round to ovoid nucleoli. These cells had moderate amounts of basophilic cytoplasm that frequently contained multiple small punctate vacuoles. Occasional cell clusters contained distinct intercellular junctions and/or piling of cells, as well as multiple ruptured cells.Rare binucleated cells, nuclear molding, and mitotic figures were observed. These findings were compatible with a carcinoma of neuroendocrine origin. The primary differential diagnosis was an insulinoma.Thoracic radiographs were acquired prior to surgery and revealed no evidence of metastasis. A partial pancreatectomy was performed of the right limb along with surgical excision of 2 regional lymph nodes, and Figure 1. Fine-needle aspirate of a pancreatic mass in a dog. Note a cluster of malignant epithelial cells with moderate amounts of pale basophilic cytoplasm with varying numbers of small punctuate vacuoles, and round nuclei with a fine chromatin structure and prominent nucleoli. There are also a few bare nuclei and ruptured cells, suggestive of neuroendocrine origin. Modified Wright-Giemsa. Bar = 10 lm.

Clinicopathological and immunohistochemical features of insulinoma in an adult mixed breed dog

“…In addition, histopathological examination showed polygonal to round pancreatic islet-cell groups with round to oval nuclei and evident nucleoli, binucleation, and eosinophilic cytoplasm surrounded by connective tissue septae. Pleomorphism, anisokaryosis anisocytosis, and mitotic figures were also observed in our case; these characteristics have been previously reported (9). Insulinoma is characterized into three stages based on the neoplasm dispersion.…”