Table 1 Causes of gonadotropin-dependent precocious puberty.

(i) Idiopathic

(ii) Central nervous system tumors (through direct or indirect effects on GnRH):

(1) Arachnoid cysts

 (2) Craniopharyngiomas

 (3) Ependymomas

 (4) Germinomas (non-HCG secreting)

 (5) Low-grade gliomas (juvenile pilocytic astrocytomas; optic pathway gliomas)

(iii) Paraneoplastic conditions (through the action of HCG on the LH receptor):

 (1) Germ cell tumors:

      (a) CNS

      (b) Gonadal

      (c) Hepatic

      (d) Mediastinal (can occur in Klinefelter's syndrome)

 (2) Hepatoblastoma

(iv) Developmental anomalies (through direct or indirect effects on GnRH):

 (1) Arachnoid cysts

 (2) Hydrocephalus

 (3) Hypothalamic hamartomas

(v) Postirradiation (through direct effects on GnRH):

 (1) Radiation therapy for childhood cancers (girls more susceptible)

(vi) Post-infectious, trauma, and bleed (through direct or indirect effects on GnRH):

 (1) Sometimes associated with arachnoid cyst development