A diagram showing the most common sites for<unk>  to spread 5 year relative survival by stage at diagnosis for<unk>  of the skin in the United States as of 2014 Factors that affect prognosis include: * tumor thickness in millimeters (Breslow's depth), * depth related to skin structures (Clark level), * type of<unk> , * presence of ulceration, * presence of lymphatic/perineural invasion, * presence of tumor-infiltrating lymphocytes (if present, prognosis is better), * location of lesion, * presence of satellite lesions, and * presence of regional or distant metastasis. Certain types of<unk>  have worse prognoses but this is explained by their thickness. Less invasive<unk> s even with lymph node metastases carry a better prognosis than deep<unk> s without regional metastasis at time of staging. Local recurrences tend to behave similarly to a primary unless they are at the site of a wide local excision (as opposed to a staged excision or punch/shave excision) since these recurrences tend to indicate lymphatic invasion. When<unk> s have spread to the lymph nodes, one of the most important factors is the number of nodes with malignancy. Extent of malignancy within a node is also important; micrometastases in which malignancy is only microscopic have a more favorable prognosis than macrometastases. In some cases micrometastases may only be detected by special staining, and if malignancy is only detectable by a rarely employed test known as the polymerase chain reaction (PCR), the prognosis is better. Macrometastases in which malignancy is clinically apparent (in some cases cancer completely replaces a node) have a far worse prognosis, and if nodes are matted or if there is extracapsular extension, the prognosis is worse still. In addition to these variables, expression levels and copy number variations of a number of relevant genes may be used to support assessment of malignant<unk>  prognosis. Stage IV<unk> , in which it has metastasized, is the most deadly skin malignancy: five-year survival is 22.5%. When there is distant metastasis, the cancer is generally considered incurable. The five-year survival rate is less than 10%. The median survival is 6–12 months. Treatment is palliative, focusing on life extension and quality of life. In some cases, patients may live many months or even years with metastatic<unk>  (depending on the aggressiveness of the treatment). Metastases to skin and lungs have a better prognosis. Metastases to brain, bone and liver are associated with a worse prognosis. Survival is better with metastasis in which the location of the primary tumor is unknown. There is not enough definitive evidence to adequately stage, and thus give a prognosis for, ocular<unk>  and<unk>  of soft parts, or mucosal<unk>  (e.g., rectal<unk> , although these tend to metastasize more easily. Even though regression may increase survival, when a<unk>  has regressed, it is impossible to know its original size and thus the original tumor is often worse than a pathology report might indicate. About 200 genes are prognostic in<unk> , with both unfavorable genes where high expression is correlated to poor survival and favorable genes where high expression is associated with longer survival times. Examples of unfavorable genes are MCM6 and TIMELESS; an example of a favorable gene is WIPI1. An increased neutorphil-to-lymphocyte ratio is associated with worse outcomes.
Melanoma
Blue nevus
Pseudomelanoma
Seborrheic keratosis
Xanthoma
Lentigo
Nodular melanoma
Dermatofibroma