Naevoid basal cell carcinoma

The cardinal features of the naevoid basal cell carcinoma
syndrome, an autosomal dominant disorder delineated by
Gorlin, are basal cell carcinomas, jaw cysts and various skeletal
abnormalities, including bifid ribs. Other features are
macrocephaly, tall stature, palmar pits, calcification of the falx
cerebri, ovarian fibromas, medulloblastomas and other
tumours. The skin tumours may be extremely numerous and
are usually bilateral and symmetrical, appearing over the face,
neck, trunk, and arms during childhood or adolescence.
Malignant change is very common after the second decade,
and removal of the tumours is therefore indicated.
Medulloblastomas occur in about 5% of cases. Abnormal
sensitivity to therapeutic doses of ionising radiation results in
the development of multiple basal cell carcinomas in any
irradiated area. The gene for Gorlin syndrome (PTCH) on
chromosome 9 has been cloned and is homologous to a
drosophila developmental gene called patched.