Scapula fracture secondary to metastatic pulmonary carcinoma in a horse: Clinical, sonographic, radiographic, computed tomographic, and pathologic findings.

A 20-year-old Quarter horse gelding was referred for evaluation of an acute onset non-weight-bearing right forelimb lameness. Marked soft tissue swelling was apparent over the right scapula and shoulder region; no crepitus was palpable. A complete transverse fracture of the scapular neck was suspected based on ultrasonography and radiographs were obtained to confirm the presumptive diagnosis. A complete, oblique fracture of the right scapular neck with mild cranial and proximal displacement of the distal fragment was detected. Computed tomography of the upper right forelimb was performed post-mortem; lytic bony destruction of the scapular neck with a secondary pathologic fracture was observed. The lesion was considered most likely neoplastic. At necropsy a complete, comminuted fracture of the right scapula was confirmed, secondary to neoplastic invasion of the bone. A solitary, dorsally located, neoplastic mass was also observed within the parenchyma of the right caudal lung. Histopathologically, the lung and scapula lesions were similar, characteristic of a well-differentiated pulmonary carcinoma.