Detection of mammary adenocarcinoma metastases in a cat through 99mTc-thymine scintigraphy

Mammary adenocarcinomas with metastases are more common in dogs than in cats. Their incidence is 1 in every 4,000 cats. In routine veterinary practice, laboratory exams for diagnosis of these neoplasms are nonspecific and scarcely used. Even though invasive procedure, biopsy, and histopathological findings are the gold standards that define the clinical approach, the clinical evaluation, and image assessment lead the way to the proper treatment, especially when surgical intervention is a possibility. This study describes the clinical signs, histopathological aspects, radiological and scintigraphic findings of a cat with mammary adenocarcinoma and metastases evaluated one hour after intravenous administration of 99mTc-thymine. Our focus was not to discuss the pathological aspects of the disease but the Nuclear Medicine role in metastases detection. Metastases, when lesser than 4mm, could go unnoticed by radiological exams, whereas scintigraphy may detect them. Using 99mTc-thymine scintigraphy, we successfully detected unsuspected metastases in the lungs, liver, and right kidney. Early diagnosis is the key to a better rate of survival due to the given treatment and prognostic. Hence, we strongly recommend the use of 99mTc-thymine scintigraphy as a complementary tool for breast cancer diagnosis in veterinary care.