A 10-year-old spayed female Akita dog developed a mass of 41 × 81 mm in diameter on the neck. The mass was a non-functioning thyroid tumor that had invaded the posterior lymph nodes of the medial pharynx. In addition, a 30-mm-diameter mass lesion was found on the cephalic side of the left renal cortex. The patient underwent en bloc resection of the left thyroid gland and posterior medial pharyngeal lymph nodes, and a total nephrectomy of the left kidney. Histopathological examination revealed a medullary thyroid carcinoma, diagnosed as T2aN1aM1 stage IV with renal metastasis. A low-dose of carboplatin was administered as the follow-up adjuvant chemotherapy. As of the 525th disease day, the patient is stable without obvious metastasis.
An 11-year-old spayed female Chihuahua visited this hospital as a regular follow-up for the previous splenomegaly problem. Ultrasound examination revealed an enlarged spleen with a honeycomb appearance. Fine needle aspiration and polymerase chain reaction for antigen receptor rearrangement of lymphocytes suggested possible B-cell lymphoma, and the subsequent splenectomy and histopathology led to a diagnosis of mantle cell lymphoma. The patient was then monitored with no further treatments. On day 511, the peripheral lymph nodes were found enlarged, leading to a diagnosis of intermediate grade B-cell lymphoma. Genome sequencing analysis revealed that the splenic mantle cell lymphoma and lymph node lymphomas were dissimilar and that they arose independently of one another. Although our observations imply that splenic mantle cell lymphoma was treated successfully with splenectomy alone, a subsequent independent malignancy arose in the same patient.