Subungual Melanoma : Causes, Symptoms, Diagnosis, And Treatment " Brown Line On The Nail "

Subungual Melanoma, Skin Melanoma, from the ancient Greek "melas" (black) and "oma" (tumor), is an aggressive malignant formation that develops as a result of an irreversible genetic malformation of melanoblasts and melanocytes. These cells produce the pigment melanin and are responsible for skin color, sunburn, and mole formation. In recent decades, the incidence of this disease has been steadily increasing. This trend is most often due to increased exposure to ultraviolet rays and the fashion for tanning.

Melanoma, what is it?

Melanocytes synthesize pigments that are responsible for dyeing the skin, eye color, hair. Pigmented lesions that are overflowing with melanin are called moles and can persist for life. Certain exogenous causal factors (from Greek. "Exo" - external) and endogenous ("endo" - internal) characters can cause a malignant tumor of the nevi. As a result, there is a risk of developing melanoma in areas of the body where congenital or acquired nevi are: skin, less often mucous membranes, and eye retina. Altered cells can multiply and grow uncontrollably, forming tumors and metastases. Most often, one malignant tumor is found among benign "companions".

What is subungual melanoma?

Melanoma of the nail is rare but no less dangerous than other tumors of the skin and mucous membranes. It becomes visible as soon as pathological cell growth begins, but it looks like a dark, sometimes not very noticeable spot or strip on the nail, similar to the consequence of injury or something harmless. For this reason, very often the sick person does not go to the doctor and starts the disease.

Melanoma of the nail can develop from the nail bed, from the skin near the nail plate. Acral melanoma, or melanonychia, marks itself with such a characteristic line on the nail. it's often wrong about bruising.

In every doubtful case, you should consult a doctor. A special device - a dermatoscopy, allows you to detect melanoma in the early stages, which most often allows you to get rid of it without consequences. Even if the diagnosis is not confirmed, and it turns out to be a granuloma, fungus, or hematoma, treatment will be required in this case, so that vigilance is never excessive.

Treatment of subungual melanoma consists of disarticulation of the distal phalanx (in the initial stages) or amputation of the toe. If indicated (metastases in the lymph nodes), surgical intervention is supplemented with regional lymphadenectomy.

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Subungual Melanoma: Causes, Symptoms, Diagnosis, And Treatment " Brown Line On The Nail "

Subungual Melanoma Classification

In oncodermatology, several classifications have been developed and used, which take into account the histological structure of the tumor node, the number of dividing cells, and other parameters. Classification according to A. Breslow is based on the thickness of the neoplasm in millimeters. The Clarke level of penetration includes five degrees of invasion of the nail bed melanoma into the skin structures:

• First. Malignant cells are located in the epidermis and do not spread deeper than the basement membrane. This is the most favorable form of the subungual tumor node in terms of prognosis of recovery since metastases do not yet occur at this stage.
• Second. Cancer cells invade the upper layers of the papillary dermis. The basement membrane collapses. The tumor node becomes large enough for its visual identification.
• Third. The altered melanocytes fill the entire papillary layer of the dermis but are not yet detected in the reticular layer.
• Fourth. The neoplasm grows into the reticular layer of the dermis.
• Fifth. The invasive growth of melanoma is observed in the subcutaneous fatty tissue. Atypical cells are actively spread by lymphomatous and hematogenous pathways.

Subungual Melanoma Development

The melanoma of the nail of the initial stage is almost invisible. Outwardly, it is difficult to identify a malignant tumor, while the nail plate becomes dark brown and dark blue. Melanoma under the nail can also be colorless due to the small amount of melanin. Nail cancer destroys the nail slowly. Melanoma of the nail leaves no room for recovery. Timely detected melanoma under the nail makes it possible to prescribe treatment with greater efficiency. Toenail melanoma appears more often due to the presence of a weak point. Hand nail melanoma is accompanied by a change in the appearance of the fingers.

Unlike all other malignant skin tumors, in subungual melanoma, excessive insolation practically does not play any role as a provoking factor in the development of the disease. This is confirmed by the fact that the neoplasm often affects the toes, which are almost constantly covered with shoes. In addition, epidemiological data indicate that subungual melanoma is 40% more common in representatives of the Negroid and Mongoloid races.

Possible risk factors for the development of melanoma of this localization include:

• • Mechanical injury to the nail. About a third of patients with an established diagnosis noted a history of mechanical damage to the nail phalanx. Most often it affects the toes, as well as the thumb and forefinger of the working hand. In addition, cosmetic and surgical interventions, which are carried out for various nail diseases, can provoke melanoma.
  • Physical injuries - frostbite and burns, the use of a laser to heal or remove damaged nails.
  • Effects of chemical carcinogens on nails. About 10% of patients had long-term contact with chemicals (occupational hazard).
  • Hereditary factor. About 5-14% of melanoma patients have genetic defects, in particular, mutations in the CDKN2A, CDK4, MITF, VC1R genes.
  • A large number of dysplastic nevi. In the overwhelming case, the development of subungual melanoma occurs de novo, i.e., on unchanged tissues, but the risks of its development are higher in individuals with a large number of pigmented dysplastic nevi.
    Age over 60.

In Caucasians, the predisposing risk factors for melanoma are fair skin, red hair, and the presence of freckles.

Types of nail melanoma

The selection of adequate therapy for cancer under the nail is to determine its type. According to the forms of nail cancer, the following types are distinguished :

• • Superficial: develops in a horizontal position.
  • Nodular: characterized by deep penetration and rapid spread.
  • Lentigo: differs from a horizontal irregularity of staining.
  • Achromatic: characterized by a dark shade of nail melanoma.
  • Acrolentiginous: initially appears on the surface and gradually penetrates deeper, affecting, including lips, palms, and fingers. There are three types, depending on the location: nail matrix, plate, the epidermis.

How does the disease develop

Development stage nail melanoma has the following :

• • Melanoma of the nail of the initial stage is almost impossible to diagnose due to the absence of any manifestations and discomfort.
  • Stage 2 is characterized by the appearance of nodules and penetration into the depths, as well as a change in color.
  • Stage 3 occurs with damage to the lymph nodes and destruction of the nail.
  • Stage 4 occurs with damage to other vital internal organs and severe pain.

Each stage of nail melanoma has its own characteristics and characteristics.

Subungual Melanoma Causes

What causes Subungual Melanoma?

A feature of the acral-lentiginous form of melanoma is the fact that its development is provoked not by ultraviolet radiation, but by other adverse external influences. Analysis of numerous clinical observations did not reveal a connection between subungual melanoma and excessive insolation. The reasons for the development of pathology include:

• • Mechanical damage. A third of patients have a history of trauma to the nail phalanx. The big toes, thumb, and forefinger of the working hand are more often affected. Cosmetic and surgical interventions, which are performed for nail diseases, can "start" tumor growth.
  • Physical and chemical influences. Of paramount importance in the development of subungual melanoma play frostbite and burns. The cause of relapse is often an attempt to remove the neoplasm with a laser. 7.5% of patients had long-term contact with aggressive chemical and radioactive substances in the past (occupational hazards).
  • Hereditary predisposition. Genetic defects that can lead to the development of melanoma are detected in 5-14% of patients. The disorders underlying the development of familial melanoma affect the genes regulating the cell cycle CDKN2A and CDK4, the melanocyte homeostasis gene MITF, and a number of low-penetrance genes, for example, MC1R.
    In 20% of cases, melanoma develops against the background of existing congenital or acquired complex, borderline, intradermal, blue nevi. Among the predisposing factors in representatives of the Caucasian race are light skin phototype, red hair, the presence of freckles, multiple dysplastic nevi. In Asians and Africans, the subungual localization of education accounts for 50% of all cases of melanoma, in Europeans, this figure is 2%.

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Can Subungual Melanoma Cause Complications?

Subungual melanoma is characterized by an aggressive course. This is one of the most aggressive forms of this disease. A radical operation of an invasive tumor does not guarantee a complete cure and prevent recurrence or the development of metastases. Most often, metastases are found in the lungs and liver, and in terms of the degree of malignancy, they are superior to the primary tumor. As the process develops, general complications characteristic of malignant neoplasms join weakness, anemia, cachexia, etc.

It should be borne in mind that surgical removal of the primary focus of melanoma leads to a partial loss of function of the affected limb. During an operation on the hand, a visible defect is formed, which is almost impossible to hide from others, plus the functionality of the hand is impaired.

In some cases, during foot surgery, it is necessary to perform a metatarsal resection. This greatly reduces the support of the operated leg and creates an additional load on other parts of the musculoskeletal system, leading to the development of arthrosis, myositis, muscle spasms, and other disorders.

Subungual Melanoma Symptoms

What are the Symptoms of Subungual Melanoma?

Symptoms of subungual melanoma

Subungual melanoma is characterized by two stages of development: horizontal and vertical.

In the horizontal stage, pigmented subungual melanoma appears as a brown or black streak under the nail. Its color may be uneven. In a third of patients, pigmentation is expanded with the involvement of the free edge of the nail, nail fold, and skin in the process.

For non-pigmented melanoma (which, by the way, occurs in 30% of cases), such signs are not typical, and the disease remains unnoticed for a long time. The first symptoms develop in the vertical stage when the tumor begins to invasively grow into the surrounding tissue. At this time, the deformation of the nail occurs. The nail plate becomes dull and loses its natural shine. Its thickness becomes thinner, the nail becomes brittle, exfoliates, and breaks easily. As the tumor grows in size, the nail cracks and a bumpy surface appears underneath. In the case of pigmented melanoma, it will be brown or black interspersed with more pigmented areas. With mechanical contact, this surface bleeds easily.

In some cases, subungual melanoma is accompanied by a burning sensation, itching, or distention. As the pathology progresses, the tumor involves new tissues in the process, spreading to the soft tissues of the fingers, feet, or hand. The pain syndrome increases and the person cannot fully use the affected limb.

Of the systemic symptoms in melanoma, general weakness, weight loss, and persistent fever are noted. With metastasis, symptoms from the affected organs join. The rate of progression of the disease varies from patient to patient. In some cases, several years pass, while in others, metastases are detected within a year after the initial occurrence of melanoma.

Systemic manifestations

As the oncological disease progresses, the patient's general well-being is impaired. General weakness increases, there is an unreasonable loss of weight, and a persistent increase in body temperature is often observed. The rate of progression of the disease varies widely, but a year after the first symptoms are detected, the patient may become incurable due to active tumor metastasis. Cases are described when the primary melanoma underwent a reverse development, and the clinical manifestations were due to the existing regional and distant metastases.

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Subungual Melanoma Diagnosis

How is subungual melanoma diagnosed?

Subungual melanoma refers to tumors of external localization, however, timely diagnosis can be difficult due to the similarity of the clinical picture with nevi, subungual hematomas, and hemangiomas. To differentiate the nature of the neoplasm, special dermatological research methods are used:

• • Dermatoscopy is a visual assessment of pathologically altered tissues using multiple magnifications.
  • Epiluminescence microscopy is a dermatoscopic examination of pathologically altered tissues in an immersion environment. This technique makes it possible with a high degree of probability to differentiate a benign neoplasm from a malignant one.

If there are changes in the nail plate, a cytological examination of fingerprints can be performed. The final diagnosis is made after a histological report. In the case of melanoma, it is strongly not recommended to take a biopsy, so as not to provoke metastasis. Therefore, the study is carried out after radical surgery.

If within two months after the patient's treatment it is impossible to exclude subungual melanoma, a marginal resection of the nail plate with matrixectomy is performed, followed by a histological examination of the material obtained. When the diagnosis is confirmed, radical surgery is indicated.

To determine the stage of the disease, radiation research methods (ultrasound, CT, or MRI) are used, which can determine the presence of local and distant metastases.

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Subungual Melanoma Treatment

How is subungual melanoma treated?

The main point in the treatment of subungual melanoma is radical surgery. Its volume is still a controversial point. Previously, it was believed that the higher the resection was performed, the less the likelihood of recurrence and metastases. Therefore, the entire finger was disarticulated. However, the studies carried out showed no statistically significant difference in survival in patients who underwent disarticulation compared with those who underwent resection at the level of the middle phalanx of the finger. Therefore, the last option of intervention has now been adopted. This does not worsen the patient's prognosis and maximizes the quality of his life.

Radiation therapy

Radiation therapy in the treatment of subungual melanoma is used to irradiate tumor recurrence in the area of the postoperative scar. The second option of application is the impact on the area of primary lymph nodes to prevent the spread of lymphomatous metastases.

Chemotherapy

Chemotherapy for subungual melanoma can be used in two versions - systemic and regional. However, different protocols may imply adjuvant and neoadjuvant regimens.

Neoadjuvant chemotherapy involves preoperative treatment. This makes it possible to reduce the size of the tumor and create conditions for its surgical removal.

Adjuvant regimens are prescribed in the postoperative period, and their goal is to destroy the remaining malignant cells, reduce the risk of recurrence and metastasis. As part of chemotherapy, regimens containing dacarbazine, lomustine, tamoxifen, etc. are used. Unfortunately, the effect can be achieved only in 15-20% of patients.

Other treatments

Immunotherapy and gene therapy are highly promising in the treatment of subungual melanoma. For example, it has been shown that the appointment of interferon, interleukin-2, or granulocyte-macrophage colony-stimulating growth factor has a beneficial effect on the prognosis of treatment - overall survival increases, and the relapse-free period is prolonged.

Suppression of p53 and p16INK4a is proposed as gene therapy for melanomas. These genes activate pathological signaling pathways through which the cell acquires the ability to divide uncontrolled and invasively grow into the underlying tissues.

Can subungual melanoma be prevented?

Prevention of the development of subungual melanoma involves the following activities:

• • Protection of limbs from mechanical and physical injury.
  • Protection against exposure to chemical agents.
  • Genetic screening of individuals at high risk for familial melanoma.
  • Observation and timely removal of nevi.

What is the outlook for subungual melanoma?

The prognosis for subungual melanoma depends on many factors, the key of which are the thickness of the tumor according to Breslow, the level of invasion, and the presence of distant metastases. 5-year life expectancy in the absence of metastases is about 60%, the average median survival is 50-55 months. In the presence of metastases, the median survival rate ranges from 7 to 8 months. At the same time, carrying out a radical operation does not affect life expectancy.

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