Diagnosis of a brachial plexus tumour using magnetic resonance imaging assisted by fine-needle aspiration biopsy in a dog: a case report

This study describes a case of a six-year-old female crossbreed dog that had a three months history of progressive right thoracic limb lameness. Palpation revealed muscle atrophy of the scapular and humeral area and painfulness in this region. Magnetic resonance imaging was performed in T1and T2-weighted and STIR (short inversion recovery) sequences in sagittal and transverse planes. The masses around the scapula and humerus were heterogeneously hyper-intense in STIR and measured about 9 cm. The tumour was heterogeneously iso-intense relatively to the surrounding tissues in T-2 weighted Gradient Echo and Spin Echo sequences. After MRI fine needle aspiration of a central part of the tumour was performed. The biopsy revealed multiple round cells with very little cytoplasm and fusiform cells in which the cytoplasm created protrusions. Cells were arranged in rows or formed a homogeneous cell mass. A malignant peripheral nerve sheath tumour was diagnosed cytologically.