Answer:
Dysplastic nevus syndrome is a familial condition characterized by
the presence of large numbers of pigmented lesions, a high incidence of
melanoma, and a history of close relatives with the same findings. The
lesions are commonly less than 1.0 cm, smooth surfaced and somewhat irregular
edges. Histologically, the melanocytes are present in the epidermis and
papillary dermis, with a concentration at the dermoepidermal junction in
nests and strands. Another finding is a lymphocytic infiltration, a feature
that distinguishes it from the small congenital nevus.
The BK mole syndrome is the early description of dysplastic nevus syndrome by investigators who named it after families B and K, the first two kindreds studied.
Familial melanoma has cloned to two genes and probably a third. The
inheritance pattern is autosomal dominant. The melanoma-susceptibility
gene (CMM1) was located on chromosome 1p36. A second melonoma gene,
designated CMM2 has been mapped to chromosome 9p21 and the cell cycle regulator
p16ink4a has been proposed as the candidate gene. More recently germline
mutations in the cyclin-dependent kinase gene CDK4 (chromosome 12q14) have
recently been described in two melonoma kindreds.