To investigate brain magnetic resonance imaging (MRI) findings in patients with central precocious puberty (CPP) by age at onset and sex.

We included 130 CPP patients with brain MRI findings of the pituitary gland treated at Ewha Womans University Mokdong Hospital between February 2007 and October 2013 and divided them by age and sex: boys, girls aged ≤6 years, and girls aged >6 years. The control group comprised 224 patients who underwent brain MRIs, and we compared their incidental brain findings with those of the CPP group.

In the CPP subgroups who underwent pituitary MRIs, the frequency of incidental brain lesions was 31.6% in boys, 47.1% in girls ≤6 years and 29.8% in girls >6 years. The incidence of pituitary abnormalities was 42.1% in boys, 64.7% in girls ≤6 years and 47.9% in girls >6 years. Among pituitary abnormalities, pituitary hypoplasia had a significantly higher incidence rate in girls ≤6 years (41.2%) than in boys (15.8%) or girls >6 years (13.8%, P=0.027). Hypothalamic hamartomas were detected in one girl aged ≤6 years and in one boy, but not in girls aged 6 years (P=0.075). The incidence of pineal cysts was higher in the CPP groups and significantly higher in girls ≤6 years (47.1%) than in the control group (11.2%, P=0.001).

There was a higher incidence of brain abnormalities on pituitary MRIs and a higher incidence of pineal cysts, possibly associated with CPP pathogenesis, in younger CPP patients than in other patients.