Premature thelarche

Last revised by Arlene Campos on 12 Jan 2024

Premature thelarche is the onset of female breast development before age 7–8 years.


As with age-appropriate thelarche, premature thelarche may be asymmetric or unilateral. 

Premature thelarche may occur as an isolated event or as part of precocious puberty. Isolated premature thelarche generally occurs in girls aged 1-3 years and is non-progressive.

Radiographic features

Radiological evaluation for suspected precocious puberty should include a bone age assessment and abdominal and pelvic sonography to look for evidence of maturation of the uterus and ovaries. In addition, the ovaries and adrenal glands should be evaluated for estrogen-producing lesions, including:


At sonography, premature thelarche appears as normal developing breast tissue without a discrete lesion. 

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