Aberrant craniopharyngeal structure in the pituitary of a male Wistar rat

An aberrant craniopharyngeal structure (ACS) in pituitary is a congenital developmental abnormality. The ACS was reported during histopathological examination of safety assessment study. It was entirely located within pars nervosa of pituitary as tubular- acinar pattern made by cuboidal epithelial cells of tubulo-acinar pattern with/without lumen, ciliated, PAS positive luminal cells with secretions and were not pre-neoplastic in terms of microscopic features. The other parameters of neurobehavioral battery, clinical pathology including thyroid profile were normal and the presence of ACS was asymptomatic. The incidence of ACS was 0.002% (N=598) in male wistar rat (aged 10-21 weeks) screened for histopathology from several 28 day and 90-day studies at the facility between 2016-2021. The present case confirmed the earlier reports viz., rare incidence, male predominance, microscopic features which included possible similarity to salivary gland, nasal epithelium and an innocuous presence in the animal.