Subungual melanoma (SM) is a rare skin disorder that generally affects dark-skinned people. Get detailed information about the disease, including its causes, symptoms, diagnosis, and treatment.
It is a particular type of melanoma that occurs under the nail bed. The disorder is known to cause a dark colored line or stripe which runs along the entire length of the nail plate of sufferers and not across the actual nail.
The condition generally affects the thumb nail or the great toenail. However, it can also affect the nail of any finger or toe.
This rare disorder is usually asymptomatic. It may affect the big toe or the thumb. If the nail gets damaged without any history of major trauma, it is most likely to be caused by SM. Even when symptoms are present, they are often overlooked due to their location. They may appear as a single dark line beneath the nail. The Hutchinson’s sign is a classic symptom of the disorder. Nearly 30% of all cases of SM are amelanotic, producing very little pigment. The condition takes the appearance of a fissure or progressive nail destruction. Bleeding is frequent in this disorder. There may also be a condition known as nail dystrophy characterized by cracking, thinning, or distortions of nail plate. Since the condition mostly affects dark-skinned people, lines under nails like these are quite common and not harmful.
One should consult a doctor if the streak changes its shape or color or a new streak develops. Other symptoms of an advanced case of SM include hyper-pigmentation of skin or an injured nail bed.
The diagnosis of the disorder can be carried out by Dermoscopy which reveals a band of black or brown pigment comprising of irregular, thin non-parallel lines. Subungual melanoma is a condition of the nail which is often difficult to diagnose early because of its asymptomatic nature. Diagnosis of the disorder often occurs after the melanoma has reached a certain noticeable stage. Proper medical treatment of subungual melanoma can allow an individual to be sure of not experiencing any recurrence of the condition that is uncalled for.
The differential diagnosis of the disease involves differentiating it from a few other similar disorders, such as:
The treatment of the disease usually involves surgery, which depends on the severity and state of the center of the melanoma. A wide local excision can be performed to get rid of the melanoma if it has not advanced beyond the depth of 1 millimeter. If the melanoma goes beyond the depth of 1 millimeter, wide local excision should be followed by a lymph-node biopsy. In cases where the melanoma is found to progress to an advanced stage, complete surgical amputation of the affected finger or toe may be necessary.
Chemotherapy is an alternate way of treating SM is by, which can be used in cases where surgery is not fully effective. Chemotherapy is done with cancer-killing drugs which can attack and destroy the cancer cells.
The prognosis of the condition depends on the severity of the case. In many cases, individuals are not found to develop the disease once their affected foot or finger has been amputated. In a few other cases, the disease has been known to recur.
This melanoma is very rare, occurring mostly among African-American and Asians. SM accounts for nearly 5% of all cases of melanoma. It generally affects the big toe or the thumb. People between 40 and 70 years of age are mostly affected by this disorder.
Here are some images depicting the symptoms of SM in various individuals.
Picture 1 – Subungual melanoma
Picture 2 - Subungual melanoma Image