Intracranial invasion of a mast cell tumour in a dog: A case report and review of the literature

Abstract

Abstract Case description: An 11-year-old, female-neutered beagle was presented with a growing soft tissue mass arising within the deep tissues of the left cranial cervical region. Clinical findings: At presentation, facial asymmetry was evident along with palpable lymphadenomegaly. Magnetic resonance imaging demonstrated a locally invasive cervical mass with intracranial invasion through focal osteolysis of the occipital bone. After antihistamine administration, cytology confirmed mast cell tumour (MCT) with metastasis to local lymph nodes and liver. Treatment and outcome: The owner chose to pursue lomustine and prednisolone, which were dispensed, but, before home administration, prolonged seizures/status epilepticus occurred prompting euthanasia. Postmortem examination confirmed a high grade MCT associated with, and infiltrating through, muscle, calvarium, dura mata, leptomeninges and the underlying brain. Clinical Relevance: We present the clinical, imaging, and pathological findings of an unprecedented case of extracranial MCT tumour causing osteolysis of an imperforate flat bone (occipital bone) and intracranial invasion. Key words: dogs, intracranial, mast cell tumour, osteolysis, metastatic