Juvenile Spontaneous Mediastinal Hemorrhage with Suspect Trauma

A 6-month-old intact female American Pitbull (Canis lupus familiaris) underwent forensic evaluation for suspected blunt force trauma. Postmortem computed tomography (PMCT) identified pleural hyperattenuating soft tissue attenuating material, consistent with clotted blood, pleural effusion, a large thymus, and moderate to severe cranial mediastinal expansion with mixed fluid and lower-attenuation, soft tissue attenuating material. Histology confirmed thymic hemorrhage, while autopsy identified hemothorax, pleural blood clots, and hemomediastinum, excluding trauma, most consistent with spontaneous idiopathic thymic hemorrhage. This case highlights the utility of identifying hyperattenuating clot formation on PMCT, like the sentinel clot sign, for localizing antemortem hemorrhage and improving antemortem-postmortem correlation in forensic investigations.