Almost any condition that affects the CNS, including hydrocephalus, meningitis, encephalitis, suprasellar cysts, head trauma, epilepsy, mental retardation, and irradiation, can precipitate central precocious puberty and must be considered before central precocious puberty is diagnosed. Hamartomas are nonmalignant tumors of the tuber cinereum with a characteristic appearance on computed tomography (CT) or MRI; biopsy is rarely required. The mass of GnRH neurons secrete GnRH and cause precocious puberty. Although hamartomas are not true neoplasms, they may require neurosurgical attention. The resulting precocious puberty is responsive to medical therapy with GnRH agonists, and surgery is rarely indicated.
Other masses that cause precocious puberty are not benign. Germinomas are noncalcifying hypothalamic or pineal tumors that frequently produce human chorionic gonadotropin (hCG), which may cause sexual precocity in prepubertal boys (hCG cross-reacts with the LH receptor because of the similarity of structure between LH and hCG). Optic or hypothalamic gliomas (with or without neurofibromatosis), astrocytomas, and ependymomas may cause precocious puberty by disrupting the negative restraint of the areas of the CNS that normally inhibit pubertal development throughout childhood. These tumors may require radiotherapy, which contributes to a significant risk for hypopituitarism.
Available @ StudentConsult.com
Precocious Puberty in the Female
The most common cause of GnRH-independent precocious puberty, McCune-Albright syndrome, is more frequent in girls than boys and includes precocious gonadarche, a bone disorder with polyostotic fibrous dysplasia, and hyperpigmented cutaneous macules (café au lait spots). The precocious gonadarche results from ovarian hyperfunction and sometimes cyst formation, leading to episodic estrogen secretion. This disorder results from a post-conception somatic
True precocious Pubertal values Pubertal Pubertal values of Normal pubertal MRI scan of brain to puberty 3 yr of age
Modified from Grumbach MM, Styne DM: Puberty. In Wilson JD, Foster DW, editors: Williams Textbook of Endocrinology, ed 9, Philadelphia, 1997, WB Saunders. CNS, Central nervous system; CT, computed tomography; DHEAS, dehydroepiandrosterone sulfate; GnRH, gonadotropin-releasing hormone; hCG, human chorionic gonadotropin; LH, luteinizing hormone; MRI, magnetic resonance imaging. *In supersensitive assays.
mutation in the G protein intracellular signaling system (specifically Gsa, which leads to unregulated constitutive activation of adenylate cyclase, and of cAMP in the absence of trophic hormone stimulation), in the affected cells in ovary, bone, and skin; other endocrine organs may also autonomously hyper-function for the same reason. Hyperthyroidism, hyperadrenalism, or acromegaly may occur. Adrenal carcinomas usually secrete adrenal androgens, such as DHEA; adrenal adenomas may virilize a child as a result of the production of androgen or may feminize a child as a result of the production of estrogen.
Boys may have precocious gonadarche on the basis of a rare entity called familial GnRH-independent sexual precocity with premature Leydig cell maturation. This condition, with germ cell maturation caused by an X-limited dominant defect, produces constitutive activation of the LH receptor that leads to continuous production and secretion of testosterone without requiring LH or hCG.