Extranodal lymphoblastic lymphoma of suspected B-cell lineage in the gingiva of a racehorse, accompanied by mandibular osteolysis.

A mass developed in the mandibular gingiva of a thoroughbred racehorse. When the horse could no longer eat unassisted, it was killed and immediately autopsied. Macroscopically, the mandible exhibited extensive osteolysis, with only a small amount of bone remaining around the tooth roots.