In the past clinicians used the thickness or depth (Breslow's thickness) of a malignant

melanoma as well  as the number and rate of mitotic figures (a measure of cell division) and

whether or not the lesion was ulcerated to prognosticate on its potential for metastasis

(spreading internally) and, therefore,to decide if a biopsy of a lymph node (called a sentinel

node biopsy) was necessary.

           Other criteria used to predict the potential for spread included  males rather than

females,location in a body site such as the axilla (armpit),the presence in the specimen of

a type of white blood cell called a tumor-infiltrating lymphocyte,and regression (replacement

of part of melanoma  with other types of tissue including inflammation and ,therefore,making 

it more difficult to judge the extent of the tumor.

          Today,a very exciting new development is the analysis of melanoma tissue samples for

genetic mutations.About 60 % of malignant melanoma skin cancers contain a mutation of a

human gene called BRAF which makes a protein called B-RAF which sends signals to cells

inside the melanoma to direct cell growth.And,therefore,when a mutation occurs in this gene,

it may promote tumor growth in melanomas. A specific drug called vemurafenib is used in

metastatic melanoma to counteract this mutation. There are other genes when overexpressed 

or mutated can also cause cancer-

           In addition,there is an entity known as Familial Melanoma in which about 5 to 10 % of

melanoma patients actually inherit a mutation in a basic cell called a germ cell (a germline mutation)

which results in their  being "melanoma prone."