Malignant Thymoma with Metastases in a Dog

Abstract

An 8-year-old male Wire-Haired Fox Terrier with respiratory distress and cough had a malignant thymoma that had metastasised to the lungs, spleen, liver, diaphragm, bronchial and mediastinal nodes, and pericardium by transcoelomic, vascular, and lymphatic routes. Myasthenia gravis, which occurs in some human patients with thymoma, was not evident.There are few reports of true thymomas in dogs [5]. TALERMAN and GWYNN [6] described one case and in a review of the literature found only five cases. WATSON and FARROW [8] and HALL et al. [2] have since reported one case each. All the reported thymomas were benign with no evidence of metastasis.A case of a malignant thymoma in a dog in which there was infiltration of tissue with transcoelomic and embolic spread is described. Case ReportAn 8-year-old male Wire-Haired Fox Terrier had respiratory distress and cough. Rectal temperature was normal. Antibiotics were administered, but 3 days later the animal's condition had deteriorated, and percussion of the chest showed abnormal solidity on the right side. Although the left side retained resonance, rales were heard on auscultation. The dog died under anaesthesia prior to radiography. PathologyBoth pleural cavities contained a moderate quantity of watery bloodstained fluid. A pale, fairly firm nodular mass, 8 X 6 X 6 em, containing areas of haemorrhage and brown discolouration was in the anterior mediastinum, and a similar mass, 6 X 3 X 3 em, was in the posterior mediastinum ( fig. 1).at OAKLAND UNIV on June 9, 2015 vet.sagepub.com Downloaded from

The cytopathological features of thymoma in a dog

“…Further sections of the entire mass were unavailable. Hassels corpuscles have been described in another case of malignant thymoma in a dog (Robinson, 1974), but they were not found in this case.…”

Lymphocytic thymoma in cavalier king charles spaniel - case report and review

“…Hassall's corpuscles usually present when the materials are fixed with formalin and stained with hematoxylin-eosin (H&E) (19). Some researchers have described structures resembling Hassall's corpuscles as an uncommon in thymoma (20) but in the present case these structures were seen. Paraneoplastic syndromes like myastenia gravis, exfoliative dermatitis, erythema multiforme, hypercalcemia, T-cell lymphocytosis, anemia and polymiositis are common in dogs and cats (21).…”

Thymomas in Domestic Animals

“…Metastatic lesions were not seen in the neoplasms reviewed in this study, although a canine thymoma is reported to have undergone metastasis and transcoelomic implantation [14]. Capsular invasion was a prominent feature in all three ovine thymomas in this study, and there were implantations of neoplastic cells upon the pericardium in the feline thymoma.…”