Melanoma subtypes challenging to diagnose, treat
Experts advise on tending to patients with lentigo maligna and acral lentiginous
Lentigo Maligna of the scalp
Lentigo maligna (LM) and acral lentiginous melanoma (ALM) can be challenging to diagnosis and treat, according to experts. Here, they offer insight into incidence, presentation, and management options.
“Diagnosing early melanomas in these anatomical locations can be challenging,” according to Clara Curiel-Lewandrowski, M.D., associate professor of medicine and dermatology, and clinical director, Cutaneous Oncology Program, Skin Cancer Institute, University of Arizona, Tucson, Ariz. “It is important to examine the hands and feet, including the nails, and to closely evaluate and monitor pigmented lesions that are new or appear to be changing in these anatomic locations.”
LM usually presents in chronically sun-exposed areas, including the face (i.e., nose, cheek and forehead), neck and dorsal hands. It appears as a slow-growing light brown to black lesion with irregular borders. The pigmentation can be similar throughout the lesion or with areas of color variegation, explains Dr. Curiel-Lewandrowski, M.D.
Acral lentiginous melanoma (ALM), in comparison, presents on palms, soles (more common than hands) or beneath the nail (subungual melanoma).
“It can arise de novo in normal-appearing skin, or it can develop from a pre-existing melanocytic nevus,” she says.
ALM usually starts as a slowly-enlarging flat macule of pigmented skin. “The presence of melanoma cells within the epidermis can persist in this location for months or years before it becomes invasive,” Dr. Curiel-Lewandrowski says. “Nodular melanomas can also evolve in these anatomical locations demonstrating a more rapid progression.”
Oftentimes, patients initially believe ALM is simply an insignificant area of depigmentation. The color varies from a mixture of brown and blue-grey or black and red. It can also be pinkish/red, or have no pigment.
Typically, ALM measures several centimeters in diameter. At first, ALM has a smooth surface because the epidermal layer is relatively thicker in these locations. It later becomes thicker with an irregular surface that may become warty; ulceration or bleeding may occur.