Although the number of reports describing
tumors in aged NHP has increased, spontaneous
neoplasias in NHP are extremely rare, with the notable exception of prosimians, in which spontaneous
hepatic neoplasms arise. In addition to radiography and ultrasonography, superparamagnetic
iron oxide (
SPIO)-enhanced MRI tends to be applied in human practice to non-invasively locate, identify, and size liver
tumors and to define the border between neoplastic and normal tissues. Here we report a 13-y-old female cynomolgus monkey with
anorexia and serologically normal liver
enzymes. After
fluid therapy, the condition remained in remission for several months. Later, however, a palpable mass was assessed by using ultrasonography, radiology, and
SPIO-MRI; T2-weighted images revealed a clear border between a
hepatocellular carcinoma and normal liver tissue. Findings at necropsy supported the imaging data. Serologic assessment after
euthanasia revealed a positive reaction to an abnormal form of
prothrombin (
PIVKA-II). We recommend
SPIO-MRI as a practical and useful for diagnosing hepatocellular
neoplasias in NHP. This study is the first to demonstrate the applicability of
SPIO-MRI for the identification of
hepatocellular carcinoma in NHP.