Summary: The coexistence of neurofibromatosis type 1 (NFT1) and Turner syndrome (TS) has only been reported in a few patients and may represent a diagnostic challenge. We describe the case of a 16-year-old girl, with a prior clinical diagnosis of NFT1, who was referred to Endocrinology appointments for the etiological study of primary amenorrhea. Evaluation of the anterior pituitary function was requested and hypergonadotropic hypogonadism was detected. During the etiological study, a 45X karyotype was found and TS was diagnosed. The fact that NFT1 can also be associated with short stature, short broad neck and hypertelorism was likely responsible for TS being diagnosed in late adolescence. As both TS and NFT1 are relatively common genetic disorders, it is important to be alert to the possibility that the presence of one disease does not invalidate the other.
Learning points: The concomitant presence of two syndromes in the same patient is unlikely and represents a diagnostic challenge. Some phenotypic characteristics and clinical manifestations may be shared by several syndromes. Some syndromes, such as neurofibromatosis type 1 may have very heterogeneous presentations. It is important to be alert to the characteristics that are not explained by the initial diagnosis. If such features are present, diagnostic work-up must be performed regardless of the initial syndromic diagnosis.