In 1977 when he injured his foot while playing soccer with some friends, Reggae legend Bob Marley decided to see a doctor after noticing that his wound was getting worse instead of healing. It was then that he was diagnosed with melanoma (a rare condition in people of African descent, but one that does occur).
Bob Marley’s medical records were never made public but he was said to have been diagnosed with acral melanoma under his toenails.
What is Acral Melanoma?
- Acral melanoma (AM) is an uncommon melanoma subtype occurring on the palms, soles and under nails.
- The incidence of AM is equal among races, but it is the most common melanoma subtype in dark-skinned populations due to the rarity of other melanoma subtypes.
- Unlike other more common types of melanoma, it’s not caused by UV damage from the sun.
- It is estimated to account for only 1–3% of cutaneous melanomas in Australia and up to 36% in dark-skinned populations.
In a study by Dr. Jennifer Stein, an associate professor in the department of dermatology at NYU Langone Medical Center in New York City, Acral pigmented lesions, which have not been well studied in people with darker skin, were found on 30 percent of white patients and 40 percent of those with darker skin. The researchers also found that 44 percent of patients with the darkest skin had the lesions, compared with 28 percent of those with the lightest skin. Acral pigmented lesions were also associated with a higher number of moles, especially among minority patients.
Patients with Acral Melanoma most commonly present with lesions that have changed in size, colour or form, or that are bleeding, painful or itchy. The diagnosis of AM is often delayed because the patients have attributed their symptoms to much more common benign conditions, the most common being warts, fungal infections, haematomas and ulcers.
Clinically, AM can be pigmented and appear as a classical melanoma with asymmetry, border irregularity, colour variation, a diameter >6 mm and evolution of the lesion. However, a large proportion of AM is amelanotic, appearing pink in colour, and making diagnosis much more difficult. It can be as subtle as a change in skin texture, appear pink and nodular or ulcerated. As a consequence, AM can easily be misdiagnosed and a high index of suspicion is needed when managing lesions of the feet and hands.
Diagnosis
The ideal method of diagnosis of melanoma should be complete excisional biopsy, however, the location of the melanoma may require alternatives.
Dermatoscopy of acral pigmented lesions is very difficult, but can be accomplished with diligent attention.
Initial confirmation of the suspicion can be done with a small wedge biopsy or small punch biopsy. Thin deep wedge biopsies can heal very well on acral skin, and small punch biopsies can give enough clue to the malignant nature of the lesion. Once this confirmatory biopsy is done a second complete excisional skin biopsy can be performed with a narrow surgical margin (1 mm). This second biopsy will determine the depth and invasiveness of the melanoma and will help to define what the final treatment will be.
If the melanoma involves the nail fold and the nail bed, complete excision of the nail unit might be required. Final treatment might require wider excision (margins of 0.5 cm or more), digital amputation, lymphangiogram with lymph node dissection, or chemotherapy.
To read more about Acral Melanoma, click here .
