Delayed Puberty due to Pituitary Stalk Dysgenesis and Ectopic Neurohypophysis
A 22-year old man was referred to our clinic because of the absence of the development of secondary sexual characteristics. The past medical history was unremarkable there were no significant pregnancy or perinatal problems. The family history was negative for growth failure, pituitary or thyroid disease. During childhood, the patient reported that he had always been short for his age. However, after a delayed growth spurt, he began to grow steadily at 20 years of age. At the time of admission, he was 183 cm. He weighed 75 kg and his body mass index (BMI) was 22.4 kg/m2. He had normal intelligence and normal body proportions. His bone age was 15 years, which was slightly below expected. X-ray evaluation of both hands showed open epiphysis (). Physical examination revealed a micropenis, no pubic or axillary hair and palpable though small testes (). These findings were compatible with a Tanner stage I development. The patient had a high pitched voice and appeared young for his stated age. The patient denied physical discomfort, had no signs of gynecomastia, no signs of orthostatic hypotension, nor any symptoms that could be associated with hypothyroidism.\nThe laboratory findings showed normal erythrocyte sediment rate, hematological parameters, blood glucose, serum sodium, potassium, calcium, phosphate, magnesium, and creatinine. Random testosterone (0.08 ng/mL, reference range 2.4~18.3 ng/mL) and luteinizing hormone (LH) (below 0.1 mLU/mL, reference range 0.4~5.7 mLU/mL) levels were all low; the follicle stimulating hormone (FSH) levels were within normal limits. The karyotype was normal, 46,XY. As a result of the random sexual hormone levels and karyotyping analysis, we could classify the delayed puberty as hypogonadotropic hypogonadism. Therefore, we performed a combined pituitary function stimulation test and pituitary MRI for further assessment. We injected regular insulin (0.1 u/Kg), TRH (200 ug), and LHRH (100 ug) and observed that 2 hours later the blood sugar fell to 60 with patient complaint of hypoglycemic symptoms. The combined pituitary function stimulation test showed no increase in serum LH, FSH, growth hormone (GH), adrenocorticotropin hormone (ACTH) level, and the serum levels of prolactin and thyroid stimulating hormone (TSH) showed a normal increment (). The MRI showed decreased pituitary stalk enhancement and an enhancing structure in the hypothalamic area, which appeared to be ectopic neurohypophysis ().\nTherefore, considering the results of the above evaluation, the delayed puberty, in this 22 year old man, was the result of hypopituitarism due to pituitary stalk dysgenesis and ectopic neurohypophysis.\nThe patient was started on hormone replacement therapy with prednisolone 5 mg/day, levothyroxine 0.1 mg/day and testosterone 250 mg IM every 3 weeks. After 3 months of treatment, secondary sexual characteristics began to develop; pubic and axillary hair was noted and the voice changed to a lower pitch. The serum testosterone level, previously 0.08 ng/mL, increased to 0.57 ng/mL.