What structures are missing?
Olfactory bulbs, and olfactory sulcus (separating gyrus rectus from the medial orbital gyrus).
What is the likely diagnosis?
What presentation would have led to the diagnosis in this 16 year old?
Primary amenorrhea and absence of puberty (due to hypogonadotropic hypogonadism).
Single coronal T2 image through the frontal lobes demonstrates abnormal anatomy with absence of the olfactory bulbs and olfactory sulcus. The gyrus rectus and medial orbital gyrus form a single gyrus.