Amelanotic Melanoma: How to Recognize a Rare Form

Amelanotic, or achromatic, melanoma is a rare form of melanoma, one of the most dangerous malignant skin tumors. We explain how it is recognized and which examinations help establish the diagnosis.

What achromatic melanoma is

Melanoma is a malignant tumor arising from melanocytes, the cells that produce the pigment melanin. Most often it develops in the skin, less often in the retina of the eye and on mucous membranes. The tumor often recurs and metastasizes via lymphatic and hematogenous routes to almost all organs, and the body responds poorly to it, so the disease often progresses rapidly.

Among the clinical forms of cutaneous melanoma, superficial spreading (about 70% of cases), nodular (15%), acral lentiginous (10%), and lentiginous (5%) are distinguished. Achromatic, that is, amelanotic, melanoma is noted as very rare.

Causes and risk factors

The leading risk factor is ultraviolet radiation: solar and artificial, from tanning equipment. Other factors include ionizing radiation and radiation burns in the past, fair skin, blue eyes, blond hair and freckles, sunburns, dysplastic nevus, a family history of melanoma, more than 50 moles, xeroderma pigmentosum, and age over 50 years.

What amelanotic melanoma looks like

The classic signs of melanoma are a change in the size, shape, color, or sensations of a mole, the appearance of a new mole, and an area of black or black-blue color. The ABCDE rule is used as a memory aid: asymmetry, irregular or blurred border, uneven color, change in diameter (usually an increase), and evolution over the past weeks or months.

In the amelanotic form there is no dark coloration, so the "color" criterion almost does not apply. Asymmetry, irregular border, growth, and changes over time remain. The following changes in a mole raise suspicion:

• an increase in the size of the mole or spot;
• a change in outline, blurred or irregular edges;
• itching in the area of the lesion;
• ulceration and bleeding of the surface;
• nodule formation, hair loss from the surface, disappearance of the skin pattern.

Nodular melanoma grows into the thickness of the skin and is considered the least favorable in terms of prognosis.

Why the diagnosis is not made by eye

In most cases it is impossible to determine the type of mole macroscopically — this also applies to lesions without pigment. A lesion without pigment may be mistaken for a benign neoplasm or another disease: in patients with diabetes, malignant skin tumors may be confused with diabetic foot ulcers. Therefore, examination is supplemented with instrumental assessment.

How diagnosis is carried out: dermatoscopy and biopsy

Dermatoscopy is considered the earliest method for diagnosing melanoma. It is performed with a simple magnifying glass or a dermatoscope — an epiluminescence microscope that makes the stratum corneum of the epidermis transparent — and the danger of a mole is assessed using the ABCDE system proposed by Friedman in 1985. Computerized microdermoscopy systems increase the level of early diagnosis from 60% to 90%, but often only under experimental conditions.

The definitive diagnosis of melanoma is established only after histological examination. For this, a skin biopsy is performed; the list of examinations for melanoma also includes sentinel lymph node biopsy, lymphoscintigraphy, and the BRAF genetic test.

When to see a doctor

You should see a doctor for any mole that changes: grows, changes its outline, itches, ulcerates, or bleeds, as well as for nodule formation.

A pink spot or nodule by itself is not a reason to call an ambulance. 103 or 112 — if signs of a life-threatening condition appear.

The material is for reference and does not replace a doctor's consultation: the decision on examination is made by a specialist after an examination.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer