Type 1 segmental cutaneous leiomyomatosis.

Cutaneous leiomyomas are rare benign tumours of the skin, which present in multiple disseminated, segmental or solitary forms. The pathogenesis of segmental cutaneous leiomyomatosis is not yet fully known. Most recently two types of segmental manifestation of autosomal dominant inherited diseases were postulated. Type 1 reflects heterozygosity for the underlying mutation with a clinical picture similar to that in a non-mosaic phenotype. In type 2, loss of heterozygosity leads to homo- or hemizygosity with a pronounced segmental manifestation of lesions in the affected segment. In our patient the lesions were restricted to one segment and therefore she most probably has a type 1 segmental cutaneous leiomyomatosis.