Familial aberrant mammary tissue: a clinicoepidemiological survey of 18 cases

Aberrant mammary tissue (AMT) is a common minor cutaneous anomaly located along the embryonic mammary line. It may be sporadic, familial or associated with nephrourinary malformations.

To investigate the frequency of family history of AMT and its possible inheritance.

We investigated a population of 156 adult Caucasian subjects affected with AMT. The familial background was evaluated primarily by using a questionnaire and by direct study of family members when available. Renal ultrasound examination was also performed to disclose the presence of kidney and urinary tract malformations.

Eighteen patients (11.5%), 12 males and 6 females, had one relative with AMT (parents: 8, sons: 5, brothers/sisters: 3, other: 2). A male-to-male transmission was found in 9 cases (75%), female-to-female and female-to-male ones in 2 cases and a male-to-female one in 1 case. No patient had nephrourinary defects.

The frequency of familial AMT in our study is very high and reflects both racial factors and the large number of the subjects surveyed. There is no distinctive clinical pattern for familial AMT, although pseudomamma (13 cases, 72%) and the left-sided location of the defect (66%) may suggest a 'hereditary predisposition'. Inheritance is consistent with an autosomal dominant transmission, although an X-linked dominant transmission is also possible. Finally familial AMT does not seem to be related to a higher association with nephrourinary malformations.