Article
Thelarche
Thelarche is the onset of secondary breast development (Tanner Breast Stage 2) and is often the first visible sign of puberty in females. Average age is ~10–11 years (range 8–13).
Physiology
- Estradiol stimulates ductal epithelial proliferation and periductal stromal changes.
- Local growth factors (IGF-1) synergize with estrogen; GH amplifies via hepatic and local IGF-1.
- Adipose deposition contributes to contour as lobuloalveolar structures expand.
Clinical Notes
- Unilateral or asymmetric budding is common and usually benign.
- Mastalgia (tenderness) frequently accompanies rapid early growth.
- Isolated breast development without other pubertal signs is termed premature thelarche; often self-limited. Distinguish from central precocious puberty by lack of growth acceleration and low gonadotropin levels.
Related Sequential Events
Typically followed (within months) by pubarche, growth spurt acceleration, and eventual menarche several years later. See puberty, gonadarche, pubarche, menarche, breast_development.