Melanoma

Introduction

Melanoma is the most dangerous type of skin cancer and accounts for the highest amount of skin related deaths (41%). It is a common cause of cancer in both men and women and its incidence increases with age. Early detection is key, as delayed diagnosis results in poor clinical outcomes. Survival is largely dependent on the stage the melanoma is detected. Melanoma stages range from 0 - IV. There are a multitude of subtypes that demonstrate varying clinical characteristics. They arise as superficial tumors in the epidermis. At this point, they can grow radially or penetrate deeper into the skin. Thickness of the tumor carries the highest prognostic value, with a thicker tumor resulting in higher morbidity. 

Epidemiology

The incidence of melanoma may vary among countries. According to one study, Australia had the highest rates (37 per 100,000) of melanoma while those in South-Central Asia had the lowest incidence (0.2 per 100,000). There are variables that factor into melanoma incidence, including skin type and degree of sun exposure. More importantly, melanoma incidence is rising annually and at a rate faster than other malignancies. 

The median age of melanoma incidence is 57 years of age, but maintain gender-specific variances. Incidence of melanoma predominates males in the younger age groups (4:10 in 20-24-year-olds), whereas male incidence increases in later decades (16:10 in >85-year-olds). Notably, mortality rates are higher in men than in women. 

The environment plays a significant role in the development of melanomas. Excessive ultra-violet (especially UV-B) radiation exposure is a risk factor for the development of melanoma. This is evidenced by the elevated incidence in equitorial regions. In addition, repeated, intense sun exposure also plays a role.

Clinical Diagnosis

Risk Factors

Patients should be thoroughly screened for the presence of a melanoma. The most important consideration is recent evolution of lesion and should be evaluated by a dermatologist. Personal history of melanoma, a first-degree family history of melanoma, excessive sun exposure/tanning bed usage, and history of severe sunburns should also be appraised. Individuals who have a fair-complexion, red/blonde hair, light eye colors, and a large number (>50) of melanocytic nevi are also at increased risk for developing melanoma. Cancer prone syndrome (e.g. familial atypical mole-melanoma syndrome and xeroderma pigmentosum) and immunocompromised patients should be regularly monitored for malignancy. 

 

 

Visual Inspection

Melanomas can be assessed in a multitude of ways. In 1985, the ABCDE criteria was formed. This criteria assesses asymmetry, border irregularity, color variegation, diameter >6mm, and recent evolution. While this is often the most common criteria to assess for melanoma, its sensitivity and specificity may vary among providers. For patients with signature nevi, presence of an "ugly ducking" should be assessed, where a pigmented lesion does not appear to match the patients other pigmented lesions. 

A new criteria system, the Glasgow seven-point checklist, was developed in the 1980's and also serves as a checklist for biopsy indication. If a lesion demonstrates at least one major criteria or three minor criteria, referral/biopsy is indicated.

Major:

  • Change in size/new lesions
  • Change in shape
  • Change in color

Minor:

  • Diameter >7mm
  • Inflammation
  • Crusting or bleeding
  • Sensory change

 

 

Melanoma SubTypes

Four main types: 

  1. Superficial spreading
  2. Lentigo maligna
  3. Acral lentiginous melanoma
  4. Nodular melanoma
  5. Other
    • Amelanotic melanoma
    • Spitzoid melanoma
    • Desmoplastic melanoma
    • Pigment synthesizing (animal-type) melanoma

 

Considerations

Although these criteria serve as a guide for the screening and assessment of possible melanoma, there are instances which a melanoma would not fit this criteria and clinical judgement is necessary. Melanoma subtypes such as nodular, desmoplastic, hypomelanotic, and amelanotic melanomas are examples of malignancies that may illude providers. For these lesions, further characteristics such elevation, firmness, and continuous growth must be considered. 

 

Histopathology

Blah blah

Management

Tumor thickness

1. 10-year survival is 92 percent for patients with melanomas ≤1 mm thick and declines to 50 percent for patients with tumors >4 mm thick.