Ask the Dermatologists
My doctor tells me that I have a thin melanoma.  What does it mean to have a thin melanoma?

Hearing that you have a thin melanoma is generally good news. A thin melanoma is a melanoma that measures 1.0 millimeter (about 1/25 of an inch) or less in thickness¹. Most thin melanomas are considered highly curable when the entire lesion and a margin of normal-looking skin are removed. With this treatment, the reported 5-year disease-free survival rate exceeds 90%.

While thickness is the primary factor used to determine a patient’s prognosis, it is not the only consideration. The patient’s overall health and other characteristics of the melanoma aside from thickness play a role. A small percentage of patients with thin melanomas have had the melanoma recur (return). Often the recurrence does not happen for several years. Other patients diagnosed with a thin melanoma have had the melanoma metastasize (spread).

For this reason, doctors consider a number of factors before determining treatment. Weighing heavily into the treatment decision are the findings from the biopsy. When examined under a microscope, some thin melanomas have features that indicate an aggressive nature. If this is the case, the wide excision — surgery to remove the entire lesion and a margin of normal-looking skin — may be followed by another therapy. Called adjuvant therapy, this second therapy is meant to reduce the risk of the melanoma spreading or returning.

Some patients diagnosed with an aggressive thin melanoma that measures between 0.75 and 1.0 millimeters undergo a sentinel lymph node biopsy (SLNB). This surgery removes lymph nodes nearest the melanoma so that they can be examined for evidence of cancer. A SLNB is typically performed at the same time as the wide excision.

Follow-up Care Essential
As melanoma can recur and spread, every patient diagnosed with melanoma should:

• Receive regular follow-up examinations by a dermatologist

• Learn how to perform a self-examination of the skin and lymph nodes

• Follow a comprehensive sun-protection plan to protect the skin from harmful ultraviolet (UV) rays of the sun

• Never use artificial tanning devices such as tanning beds

Protecting one’s skin from UV rays reduces the risk of developing skin cancer and may reduce the risk of melanoma recurring. Examinations are essential because the earlier melanoma is detected, the better the prognosis. When limited to the outermost layers of the skin, melanoma averages a 95% cure rate.

¹ The thickness of a melanoma is measured during the biopsy when the lesion is being examined under a microscope. Measured in millimeters, the thickness tells us how deeply the melanoma has burrowed into the skin. Also called Breslow thickness, this measurement is named after Alexander Breslow, MD, the doctor who created it.

References:
1 Corsetti RL, Allen HM, Wanebo HJ. Thin < or = 1 mm level III and IV melanomas are higher risk lesions for regional failure and warrant sentinel lymph node biopsy. Ann Surg Oncol 2000; 7: 456-60.

2 Kalady MF, White RR, Johnson JL et al. Thin melanomas: predictive lethal characteristics from a 30-year clinical experience. Annals of surgery 2003; 238: 528-35; discussion 35-7.

3 Tsao H. The Lethal Thin Melanoma — Wolf in Sheep's Clothing. In: Journal Watch Dermatology. 2007.

An educational program brought to you by the American Academy of Dermatology.