仙骨直腸奇形腫による小児異所性ACTH症候群の課題

Ectopic ACTH syndrome (EAS) is a rare cause of Cushing's syndrome, especially in children, and has been only exceptionally linked to sacrococcygeal teratomas (SCTs). We report a pediatric case of SCT-associated EAS and review the literature to highlight diagnostic challenges and management strategies.

A 13-year-old girl presented with hypertension, hypokalemia, hyperglycemia, and rapid weight gain. Biochemical testing confirmed ACTH-dependent hypercortisolism, while pituitary MRI was negative. Pelvic CT revealed a 5.1 cm presacral mass. PET/CT based on ^18F-FDG showed only mild glucose uptake (SUVmax 3.26) in the mass, whereas ^68Ga-DOTA-NOC PET/CT demonstrated intense somatostatin receptor (SSTR) expression (SUVmax 55.86). Laparoscopic resection identified a mature teratoma containing a well-differentiated neuroendocrine tumor (NET G1) positive for ACTH and SSTR2. Postoperatively, cortisol/ACTH levels normalized, and metabolic abnormalities resolved with 9-month follow-up showing no recurrence.

This report describes the first adolescent case of EAS due to a neuroendocrine tumor within a sacrococcygeal teratoma. Complementary PET/CT on FDG metabolism and SSTR expression is critical for localizing occult neuroendocrine components. Complete tumor resection and multidisciplinary collaboration are key to favorable outcomes, expanding the spectrum of pediatric EAS and providing valuable insight into its evaluation and management.