Clinical Review

Becker's nevus syndrome revisited

Spectrum of anomalies

The following developmental defects occur within the spectrum of Becker's nevus syndrome (Table I).

Sex ratio

Most authors so far believe that isolated Becker's nevus occurs more frequently in male than in female patients, with a 2:1 ratio. Happle and Koopman,⁴ however, suggested that the true sex ratio may in fact be 1:1, because Becker's nevus tends to be less conspicuous in female patients. Conversely, this review shows that Becker's nevus syndrome is more frequently reported in female than in male patients, with a ratio of 1.5:1. This may be best explained by the fact that ipsilateral hypoplasia of

Pathogenetic considerations

Both Becker's nevus and mammary hypoplasia can be explained as hormone-dependent disorders caused by a disturbance of receptor activity.8., 43. The associated musculoskeletal anomalies, however, are difficult to explain by this pathogenetic mechanism.

The majority of developmental anomalies are hypoplastic lesions.¹⁰ By contrast, several authors described enlargement of an ipsilateral limb,14., 35., 36. but we can so far not exclude that, at least in some of these cases, the asymmetry was caused

Genetic basis

In 1997 Happle and Koopman⁴ suggested that Becker's nevus syndrome might represent a paradominant trait. They provided the following arguments in favor of this concept: isolated Becker's nevus virtually always occurs sporadically, but some authors have reported several affected members of a family,5., 52., 55., 56., 57., 58., 59., 60., 61. suggesting the role of a genetic factor. Autosomal dominant inheritance with incomplete penetrance and variable expressivity has been assumed.57., 59. Such