An expansile secondary hypophyseal mastocytoma in a dog

A 5-year-old mixed breed dog was presented with a history of depression and anorexia. Physical examination revealed a pharyngeal tumour and a neurological examination indicated the presence of a possible space-occupying lesion in the brain. Investigative procedures included a bloodsmear, impression smears and cytology of the pharyngeal tumour, haematology, chemical pathology, faecal analysis, urinalysis, electrocardiography, cerebrospinal fluid analysis, hormone assays and a computerised axial tomography scan. Results of these investigations revealed a round cell tumour in the pharynx, hypergammaglobulinaemia (34 g l-1), azotaemia (urea 8.6 mmol l-1 and creatinine 170 mumol l-1), hypoalbuminaemia (20 g l-1), proteinuria, sinus bradycardia (heart rate 60 beats per min), increased concentration of protein in the CSF (1.1 g l-1), hypoadrenocorticism (base line cortisol less than 55 nmol l-1) and hypothyroidism (T4 less than 13 nmol l-1). The computerised axial tomography scan revealed a brain tumour in the region of the hypophysis. The dog was euthanased and a post mortem examination confirmed the presence of a pharyngeal tumour with apparent direct extension of the tumour into the brain. Both tumours were confirmed histologically as mastocytomas.