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Melanoma and other skin cancers - Diagnosis

Description

An in-depth report on the causes, diagnosis, treatment, and prevention of melanoma and nonmelanoma skin cancers.

Alternative Names

Skin cancer; Squamous cell cancer; Basal cell cancer; Actinic keratosis; Nonmelanoma skin cancer

Diagnosis:

An experienced doctor should first rule out noncancerous (benign) conditions that resemble melanoma, such as a mole called a melanocytic nevi.

In rare instances, a melanoma will be difficult to detect. For example, an uncommon form called a myxoid melanoma may be mistaken for a benign skin disorder known as a myxoid fibrohistiocytic lesion. Other opinions from a pathologist, computerized image processing, or advanced staining techniques may help to confirm the diagnosis.

A study published in the Archives of Internal Medicine has found that melanoma tends to be diagnosed at a later stage in people who are not light-skinned. The study involved nearly 50,000 patients with melanoma, and included Caucasians, Hispanics, Asian/Pacific Islanders, African-Americans, and American Indians.

Dermoscopy and Total Body Photography

A combination of imaging approaches should be considered for early melanoma detection and diagnosis since each technique alone has limitations. Some doctors now use various handheld scope-like devices (dermoscopy, dermatoscopy, or epiluminescence microscopy) that enhance the suspected lesion.

Skin Biopsy

A skin biopsy is the removal of skin tissue for examination under a microscope. The exact type of biopsy depends on how deep the lesion has penetrated the skin.

Shave biopsy uses a thin surgical blade, or scalpel, to shave off the top layers of skin. The doctor may use this type of biopsy to diagnose basal cell cancer.
Punch biopsy uses a round, cookie-cutter-like tool. It is used to take a deeper sample of the skin.
Incisional and excisional biopsies remove tumors that have grown deep into the skin. An incisional biopsy cuts out part of the tumor. An excisional biopsy removes the entire tumor. These biopsies are used to diagnose melanoma.

All of the above-mentioned biopsies can be done using local anesthesia.

Lymph Node Biopsy

A lymph node biopsy may be used for patients with recently diagnosed melanoma to help determine whether the cancer has spread to one or more lymph nodes.

A procedure called sentinel lymph node (SLN) biopsy is now recommended for cancers that are thicker than 1 millimeter. It is usually not necessary for cancers thinner than 0.75 millimeter, unless they have opened (ulcerated). Although some evidence suggests this procedure may improve survival, no clinical trials to date have proven that this procedure improves the outlook in people with thin melanoma.

Sentinel node biopsy is a technique that helps determine if a cancer has spread. When a cancer has been detected, often the next step is to find the lymph node closest to the tumor site and retrieve it for analysis. The concept of the "sentinel" node, or the first node to drain the area of the cancer, allows a more accurate staging of the cancer, and leaves unaffected nodes behind to continue the important job of draining fluids. The procedure involves the injection of a dye (sometimes mildly radioactive) to pinpoint the lymph node that is closest to the cancer site. Sentinel node biopsy is used to stage many kinds of cancer, including melanoma.

This procedure involves the following:

A tiny amount of a tracer, either a radioactively labeled substance (radioisotope) or a blue dye, is injected into the tumor site.
The substance flows through the lymph system into the sentinel node, the first lymph node to which any cancer would spread.
The sentinel lymph node and possibly one or two other nodes are removed and biopsied.

The results of the biopsy can help doctors decide whether or not to remove other lymph nodes:

If the sentinel node and other nodes show signs of cancer, the nearby lymph nodes are removed.
If they do not show signs of cancer, the rest of the lymph nodes will likely be cancer-free, and further surgery is not needed.

Secondary Tests

Patients with nom-melanoma skin cancers generally require no further workup.

Those with melanoma may need the following:

Blood tests that show high levels of lactate dehydrogenase suggest that the cancer has spread. Blood tests to assess liver function and other factors, such as anemia, help determine specific sites where the cancer may appear.
Computed tomography (CT) scans of the chest, abdomen or pelvis, may be used to identify whether the melanoma has spread at the time of diagnosis or to monitor it after treatment.
Positron emission tomography (PET) may also be used. PET may help find evidence that the cancer has spread elsewhere in the body that does not show up during a physical exam or CT scan. Sometimes this may avoid unnecessary surgeries.

Resources

www.aad.org -- American Academy of Dermatology
www.cancer.org -- American Cancer Society
www.asds.net -- American Society for Dermatologic Surgery
www.mpip.org -- Melanoma Patients' Information Page
www.cancer.gov -- National Cancer Institute
www.nccn.org -- National Comprehensive Cancer Network
www.skincancer.org -- The Skin Cancer Foundation
www.epa.gov/sunwise/uvindex.html -- UV index information

References

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Anderson L, Schmieder GJ, Werschler WP, et al. Randomized, double-blind, double-dummy, vehicle-controlled study of ingenol mebutate gel 0.025% and 0.05% for actinic keratosis. J Am Acad Dermatol. 2009;60(6):934-43.

Basal cell and squamous cell cancers: NCCN Medical Practice Guidelines and Oncology;V.1.2009. Accessed July 15, 2009.

Braathen LR, Szeimies RM, Basset-Seguin N, Bissonnette R, Foley P, Pariser D, et al. Guidelines on the use of photodynamic therapy for nonmelanoma skin cancer: an international consensus. International Society for Photodynamic Therapy In Dermatology, 2005. J Am Acad Dermatol. 2005;56:125-143.

Brantsch KD, Meisner C, Schonfisch B, Trilling B, Wehner-Caroli J, Rocken M, et al. Analysis of risk factors determining prognosis of cutaneous squamous-cell carcinoma: a prospective study. The Lancet Oncology. 2008;9:713-720.

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Cyr PR. Atypical Moles. Am Fam Physician. 2008;78(6):735-40. Review.

deBerker D, McGregor JM, Hughes BR. Guidelines for the management of actinic keratoses. Br J Dermatol. 2007;156:222-230.

Eggermont AM, Suciu S, Santinami M, et al: EORTC Melanoma Group. Adjuvant therapy with pegylated interferon alfa-2b versus observation alone in resected stage III melanoma: final result of EORTC 18991, a randomised phase III trial. Lancet. 2008;372(9633):117-26.

Garcia C, Polette E, Crowson AN. Basosquamous carcinoma. J Am Dermatol. 2009;60(1):137-43.

Goodson AG, Grossman D. Strategies for early melanoma detection: Approaches to the patient with nevi. J Am Acad Dermatol. 2009;60(5):719-35: quiz 736-8. Review.

Guadagnolo BA, Zagars GK. Adjuvant radiation therapy for high-risk notal metastases from cutaneous melanoma. Lancet Oncol. 2009;10(4):409-16.

Hexsel, CL, Bangert SD, Hebert AA, et al. Current sunscreen issues: 2007 Food and Drug Administration sunscreen labelling recommendations and combination sunscreen/insect repellent products. J Am Dermatol. 2008;59(2):316-23. Review.

Lachiewicz AM, Berwick M, Wiggins CL, Thomas NE. Survival differences between patients with scalp or neck melanoma and those with melanoma of other sites in the surveillance, epidemiology, and end results (SEER) program. Arch Dermatol. 2008;144:515-521.

Lange JR, Fecher LA, Sharfman WH, et al. Melanoma. In: Abeloff MD, Armitage JO, Nierderhuber JE, Kastan MB, McKenna WG, eds. Abeloff's Clinical Oncology. 4th ed. Philadelphia, Pa: Churchill Livingstone; 2008:chap 73.

Lautenschlager S, Wulf HC, Pittelkow MR. Photoprotection. The Lancet [early online publication]. May 3, 2007.

Markovick SN, Erickson LA, Rao RD, Weenig RH, Pockaj BA, Bardia A, et al. Malignant melanoma in the 21st century, part 1:epidemiology, risk factors, screening, prevention, and diagnosis. Mayo Clin Proc. 2007;82:364-380.

Markovick SN, Erickson LA, Rao RD, Weenig RH, Pockaj BA, Bardia A, et al. Malignant melanoma in the 21st century, part 2: staging, prognosis, and treatment. Mayo Clin Proc. 2007;82:490-513.

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Vestergaard ME, Macaskill P, Holt PE, et al. Dermoscopy compared with naket eye examination for the diagnosis of primary melanoma: a meta-analysis of studies performed in a clinical setting. Br J Dermatol. 2008;159(3):669-76.

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Reviewed last on: 7/30/2009
Harvey Simon, MD, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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