Subcutaneous lymphangiosarcoma in a pet rat (Rattus norvegicus)

An intact 1-year-old female rat (Rattus norvegicus) presented with a mass in the left axilla. Nodulectomy was subsequently performed, and biopsy results revealed a subcutaneous lymphangiosarcoma (LPS). Metronomic chemotherapy with toceranib and meloxicam was initiated. Three months later, a left axillary mass and an inguinal mass were observed. Histopathologic analysis confirmed the recurrence of a subcutaneous lymphangiosarcoma in the left axilla, and a mammary fibroadenoma in the inguinal area. The animal continued treatment with the same protocol of metronomic chemotherapy, and no tumor recurrence was observed. Lymphangiosarcoma is a rare, malignant neoplasm poorly described in animals. In the only previous report in rats, the LPS was located on the lumbosacral vertebrae. Lymphangiosarcoma should be included in the differential diagnosis of subcutaneous masses in rats.