How early can one diagnose Cushing's disease? An early diagnosis in a case of prepubertal Cushing's disease.

BACKGROUND: Cushing's disease is very rare in children, and the diagnosis is frequently delayed by several years.
OBJECTIVE: We report a case of prepubertal Cushing's disease with a medical history of only 9 months. This case illustrates the difficulties involved in diagnosing children at the early stage of the disease. CASE
PRESENTATION: An 8-year-old prepubertal boy presented with rapid weight gain accompanied by a decreasing growth velocity and hirsutism. Thyroid function tests and growth factor levels were normal, thus excluding hypothyroidism and growth hormone deficiency. Cushing's syndrome was confirmed by elevated 24-h urinary free cortisol levels, increased diurnal cortisol levels, and a lack of cortisol suppression in the low-dose dexamethasone suppression test. Further tests to investigate the source of the hypercortisolism showed the following results: Basal morning adrenocorticotropic hormone (ACTH) was normal. The high-dose dexamethasone suppression test led to a 51% decrease in cortisol level. In the corticotropin-releasing hormone (CRH) test, ACTH and cortisol increased only by 28%. Repeated magnetic resonance imaging (MRI) finally revealed a microadenoma in the anterior pituitary, thus establishng the diagnosis of Cushing's disease. Upon diagnosis, the patient underwent transsphenoidal surgery. Histological analysis confirmed an ACTH-secreting pituitary adenoma.
CONCLUSION: This case illustrates the difficulties associated with the clinical, biochemical, and radiological diagnoses of Cushing's disease in children. Early diagnosis remains a challenge because test results often do not match standard diagnostic criteria.