Cutaneous melanoma is the most common type of melanoma; however, melanomas of the hand are rare (2%) and typically occur as finger or thumb-tip lesions. Overall survival for hand melanoma is good, at ~70%. Survival is decreased in patients with subungual melanoma, likely due to diagnostic delay. The main environmental risk factor for cutaneous melanoma is ultraviolet radiation from sun exposure and tanning beds. The risk is more strongly associated with intermittent exposure to high-intensity sunlight, which leads to sunburn which increases the risk of melanoma. Heredity may be a factor in some families. 3,4 Immunosuppressed patient's are at higher risk. Early and accurate diagnosis and treatment of melanocytic lesions is critical, but difficult. Melanoma of the hand requires special attention because the skin of the hand is structurally unique to allow for fine sensibility, mobility for complex motor skills, and durability.1,2
Melanoma is classified by the Clark level and the Breslow thickness. The Clark level is defined by the depth of the melanoma cells in the dermis. The Breslow thickness guides therapy and is a measurement of thickness of the melanoma cells on biopsy.
Pathophysiology
- Cutaneous melanoma cells spread out within the epidermis (radial growth phase).
- When they reach the dermis, they can spread to other tissues via the lymphatic system to the local lymph nodes, or via the blood stream to other organs (vertical growth phase).
- There are four types of melanoma
- Lentigo malignant
- Superficial spreading
- Nodular
- Acral lentiginous
- Occurs in Blacks and Asians
- 1-3 spread horizontally and is curable if treated early
Incidence and Related Conditions
- 2% of melanomas occur in the hand.
- Worldwide, malignant melanoma accounts for 1% of all cancer deaths but for 80% of all skin cancer deaths
- Incidence rates in the United States have increased 200% since 1973; similar increases in the UK, especially in white men aged >60 years. Increases are more rapid than for any other cancer type
- Incidence is higher in women aged <50 years; twice as high in men by age 65. By age 80, rates in men are triple those in women.
- Mortality rate is higher in men (4.8 vs 2.8 deaths per 100,000).
- The incidence of melanoma is greater in the white population.
Differential Diagnosis
- Angiokeratoma (angioma)
- Blue nevus (precursor of melanoma)
- Nevus
- Dermatofibroma
- Hemangioma
- Actinic lentigo
- Pigmented actinic keratosis
- Pigmented basal cell carcinoma
- Seborrheic keratosis
- Traumatic hematoma
- Traumatized or irritated nevus
- Pyogenic granuloma