Tanner stage 4 breast development in adults: forensic implications

Forensic testimony in alleged child pornography cases commonly asserts that Tanner stage (TS) 4 breast development, characterized by secondary mounding of the areola that is obliterated in TS 5, is evidence of age <18 years. Clinical experience does not support this notion, but there are no relevant studies. We sought to estimate how frequently TS 4 might be interpreted from nonclinical images by individual forensic experts.

Published images of 547 adult women were independently examined by the authors and classified as having TS 4 or TS 5 breast development.

There was concordance among all 4 of the examiners for 17 of the images, agreement of 3 of the examiners on another 36 images, of 2 examiners on 39 images, and 53 images were designated TS 4 by only 1 examiner, for a total of 153 (26.5%) images that could have been considered by a single forensic expert to represent TS 4.

A substantial number of adults have persistent TS 4 breast development. This observation, and the frequent difficulty distinguishing TS 4 from TS 5, even by adolescent development specialists, especially in nonclinical images, renders testimony based on this distinction invalid. Without clinical relevance for distinguishing these advanced stages of breast development, they should both be considered indicative of full maturation. Testimony based on this inappropriate test of maturity should no longer be allowed.