Feline systemic reactive angioendotheliomatosis with hypercalcaemia.

CASE SUMMARY: A 3-year 10-month-old spayed female domestic shorthair cat was presented for subacute progressive hyporexia, vomiting and lethargy. On presentation, the cat was dyspnoeic, and venous blood gas analysis revealed metabolic acidosis, hypercalcaemia (both total and ionised), hyperlactaemia and hyperglycaemia. Physical examination identified a 2 × 3 cm crusted cutaneous lesion on the cranium, reduced mentation, mild tachycardia, harsh bronchovesicular sounds and approximately 5% dehydration. Owing to welfare concerns, the owners elected euthanasia. Post-mortem examination revealed moderate autolytic changes. The organs most affected by vascular lesions included the heart, brain, kidneys, liver and pancreas. Histopathology revealed mild to severe multifocal intraluminal and mural proliferations of atypical endothelial cells, accompanied by multifocal thrombosis and mild perivascular oedema. Immunohistochemistry showed that the proliferating cells were negative for alpha-smooth muscle actin, and quantitative PCR for Bartonella species was also negative. However, 50% of the proliferating cells were positive for factor VIII. These findings supported a diagnosis of feline systemic reactive angioendotheliomatosis.

RELEVANCE AND NOVEL INFORMATION: In the authors' opinion, this case contributes to the growing body of literature on this rare condition and raises the possibility of an association with hypercalcaemia.