Nodular melanoma is an aggressive form of skin cancer. Its rapid and often subtle progression makes understanding its specific characteristics important. This type of melanoma demands attention due to its potential for swift advancement compared to other forms.
What is Nodular Melanoma?
Nodular melanoma is a skin cancer originating from melanocytes, the pigment-producing cells. Unlike other melanomas that spread superficially first, nodular melanoma is characterized by early vertical growth, invading deeper skin layers from the outset. This distinct pattern makes it aggressive.
Clinically, it often appears as a raised, dome-shaped, firm lump. Its color can vary (black, red, pink, brown, or skin-colored), and its surface may be smooth, rough, or crusted. A challenge in identifying nodular melanoma is that it frequently does not follow the traditional “ABCDE” signs (Asymmetry, Border irregularity, Color variation, Diameter, Evolving), as it can be symmetrical and uniform. It is commonly found on the head, neck, and trunk.
Understanding Its Growth Speed
Nodular melanoma grows rapidly, often progressing significantly within weeks to months. This rapid progression is due to its characteristic vertical growth phase, where cancer cells invade downward into the dermis quickly, rather than spreading horizontally across the epidermis. This contrasts sharply with superficial spreading melanoma, which typically has an initial radial growth phase that can last for years before invading deeper.
The speed of this vertical invasion is measured by Breslow depth, the melanoma’s thickness from the skin’s surface to its deepest point. Nodular melanomas can penetrate deep within the skin within a few months of their first appearance. They can grow at an estimated rate of 0.5 mm per month. This means a nodular melanoma can quickly reach a thickness that indicates a higher risk of metastasis.
Influences on Growth Rate
While nodular melanoma is aggressive, several factors influence its growth. Genetic predispositions play a role, with certain gene variants increasing susceptibility. Research identifies specific gene variants more frequent in nodular melanoma patients.
Other factors include tumor location, with melanomas on the trunk, head, or neck differing from those on extremities. The body’s immune response also influences growth; melanoma cells can evade the immune system, allowing faster progression. Delays in diagnosis, often due to its atypical appearance, can mean the tumor has grown undetected for some time.
Why Rapid Growth is a Concern
The rapid growth of nodular melanoma is a concern because it correlates with an increased likelihood of metastasis, the spread of cancer to other parts of the body. As it invades deeper skin layers, it gains earlier access to blood vessels and lymphatic channels, providing pathways for cancer cells to travel to distant organs and lymph nodes.
This invasion means nodular melanoma can become life-threatening in as little as six weeks if untreated. Early metastasis negatively impacts prognosis and treatment outcomes compared to slower-growing melanomas. While nodular melanoma accounts for about 15% of melanoma cases, it is responsible for a disproportionately higher percentage of melanoma-related deaths, sometimes up to 43%.
The Importance of Early Detection
Given its aggressive nature and rapid growth, early detection of nodular melanoma is important for improving patient outcomes. Individuals should be vigilant for any new or changing skin lesions, especially those that are elevated, firm to the touch, and growing quickly (EFG rule). These lesions may appear as a new bump or nodule, and can change shape or color rapidly.
Regular self-skin exams are important, focusing on identifying any lesion that is evolving in size, shape, or color, or that bleeds, itches, or feels tender. Professional skin checks by a dermatologist are also important, particularly for individuals with risk factors. Prompt medical evaluation of any concerning skin changes can make a substantial difference in treatment and prognosis.