Human multiple endocrine neoplasia subtype 2A (MEN 2A) is characterized by medullary thyroid carcinoma, pheochromocytoma and parathyroid hyperplasia or adenoma in the same individual. In this report, a case of a female Rottweiler with medullary thyroid carcinoma, bilateral pheochromocytoma and parathyroid adenoma was described. Clinical manifestations of muscle weakness, polydipsia, polyuria, diarrhea and weight loss were observed. Two adrenal neoplasms were identified incidentally by ultrasonography, and tumor in the left thyroid lobe was identified by palpation. Primary hyperparathyroidism was diagnosed by biochemical testing. Histopathology report was consistent with diagnosis of bilateral pheochromocytoma and parathyroid adenoma. Immunohistochemical staining was positive for calcitonin and synaptophysin, and negative for thyroglobulin, which confirmed medullary thyroid carcinoma. This case in a dog is presenting neoplastic characteristics similar to human MEN 2A and emphasizing the importance of using immunohistochemistry for confirmation.

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A 12-year old dog with a 9-year history of primary adrenal insufficiency was referred to the service for hyporexia, muscle weakness, polyuria and polydipsia. Ultrasound examination showed an unresectable mass in the left adrenal gland, with local vascular invasion, which prompted the euthanasia of the animal. Additionally, necropsy revealed a nodular lesion in the right adrenal gland and enlargement of one of the four parathyroid glands. Parathyroid hormone levels were elevated, but ionized and total calcium levels were normal. Histopathology supported the diagnosis of parathyroid chief cell adenoma and bilateral pheochromocytoma. Immunohistochemical staining was positive for synaptophysin, and negative for Melan-A and calretinin, which confirmed the diagnosis of pheochromocytoma. This case highlights an unusual presentation of multiple endocrine neoplasias within the context of primary adrenal insufficiency and normocalcemic primary hyperparathyroidism.

Histopathological features of hepatocellular carcinoma (HCC) induced by diethylnitrosamine (DEN) in mice displays strong similarities with those seen in humans, including the higher tumor prevalence in males than in females. Previous studies have demonstrated that continual production of the pro-inflammatory IL-6 by Kupffer cells is involved in the initiation and progression of DEN-induced HCC and that estrogen-mediated reduction of IL-6 secretion would decrease its incidence in females. However, the mechanisms by which different IL-6 concentrations affect tumor growth are not entirely understood. In this model, we demonstrated that the increased tumor growth observed in males accompanied significant liver damage and larger chronic inflammatory areas. Most tumors were placed into or close to senescent areas (detected by expression of β-galactosidase), and these areas were more extensive in DEN-treated males than in similarly-treated female mice. Further, different markers of systemic and regional immunosuppression (such as neutrophil-to-lymphocyte ratio, PD-1 expression in CD8 T cells, number of PD-L1 + myeloid-derived suppressor cells, etc.) were significantly higher in males than in females from the time the tumors started their exponential growth, suggesting that immunosuppressive mechanisms could contribute to the accelerated tumor growth observed in males. The relationship between chronic inflammation and immunosuppression has been previously documented. In contrast, little is known about the link between senescence and immunosuppression, raising the possibility that senescence may contribute to tumor growth by mechanisms other than immunological. Comparative studies between susceptible and resistant hosts to chemical carcinogenesis may help to unveil novel therapeutic strategies against cancer.

Metastatic pituitary carcinoma and central vestibular syndrome originating in the thalamus are not common disorders in dogs. An 11-year-old Maltese dog with pituitary-dependent hypercortisolism presented signs of central vestibular dysfunction after trilostane treatment. Interestingly, the patient showed remission of vestibular signs after drug withdrawal, but two weeks later, with a new administration of trilostane, these signs reappeared after 48 hours. Postmortem, two neoplasms were found: one in the pituitary gland and the other in the thalamus, both with intense positivity for adrenocorticotropic hormone. Findings were conclusive of a functional corticotropic pituitary carcinoma with thalamic metastasis. Altogether, the vestibular dysfunction in this case was attributed to the effect of the mass in the thalamus, and the remission and reappearance of vestibular signs were associated with the level and the effect of cortisol, which depend on the trilostane therapy. Consequently, thalamic metastasis should be considered as a differential diagnosis in dogs with central vestibular dysfunction.