Melanoma: Classification and Staging

Melanoma is a severe form of skin cancer that presents in various forms, each with distinct characteristics. This article shows the classification of melanoma, emphasizing how the physical appearance of lesions provides insights into their behavior and potential risks. Understanding these variations can help early detection and effective management.

Morphological Classification of Melanoma

The classification considers the physical presentation of the lesion, primarily differentiating between flat and dome-shaped melanomas.

Flat Melanoma

Flat melanoma typically manifests in two forms: non-palpable and palpable.

• Non-palpable: This form is less noticeable to the touch and usually appears as a small, irregularly shaped lesion, often exceeding 6 millimeters in diameter. It primarily exhibits a horizontal or centrifugal growth pattern, spreading outward across the skin surface. This type of melanoma can develop on any skin area, including the mucosal surfaces, and is marked by its asymmetry and irregular borders. The coloration varies from dark brown to black, and the skin pattern over the lesion may become more pronounced or completely fade.
• Palpable: Slightly elevated above the skin, this form is detectable by touch and characterized by its asymmetrical shape with uneven, often jagged edges. The lesion's color is typically dark brown or blackish, and it might show a distinct or fading skin pattern, indicating a deeper involvement than its non-palpable counterpart.

Dome-shaped Melanoma

This less common variant grows predominantly in a vertical direction, contrasting with the horizontal expansion seen in flat melanomas.

It usually presents as a papule or nodule with a hemispherical, smooth surface. The color ranges from blackish-brown to bluish, with the pigment sometimes distributed irregularly or completely absent. The vertical growth pattern indicates a progression that may penetrate deeper into the skin, posing a higher risk of metastasis.

Flat-Dome Transition

Flat-Dome-shaped melanoma represents a critical transitional phase, this form illustrates the shift from horizontal to vertical growth. The emergence of a papule or nodule within a pre-existing flat melanoma (palpable or non-palpable) is a significant development, indicating an evolving malignancy that may require aggressive treatment. This stage underscores the dynamic nature of melanoma and highlights the importance of monitoring for any changes in existing lesions.

Melanocytic Nevus-Melanoma Link

Melanoma can develop from melanocytic nevi, which are commonly known as moles. These moles can be either acquired (appearing after birth) or congenital (present at birth). Research indicates that between 20% to 50% of melanomas are associated with pre-existing moles.

Key Warning Signs

It is important to monitor changes in moles, as certain alterations can signify the transformation from a benign mole to melanoma. Here are indicators to watch for:

1. Color Modification: Any significant change in the color of a mole, especially if it becomes uneven or multiple colors appear within the same lesion, can be a warning sign.
2. Elevation: The sudden emergence of a raised area on an otherwise flat mole is a critical change.
3. Growth: A rapid increase in size or thickness of the mole should prompt concern. Quick changes over weeks or months are particularly alarming.
4. Surface Changes: Erosion, bleeding, or the development of a crust on the mole’s surface can indicate malignant changes.
5. Inflammation: Any signs of redness or swelling around the mole can suggest an evolving pathological process.

Importance of Early Detection

Early detection and treatment of melanoma can dramatically improve prognosis. Individuals should perform regular self-examinations of their skin to identify any suspicious changes in moles and seek dermatological advice if any of the above changes are observed. It's also advisable for individuals with a high number of moles, significant sun exposure, or a family history of skin cancer to have regular skin checks by a professional.

The Evolution of Melanoma

Characteristically, melanoma undergoes irregular growth patterns and can develop ulcerations—where the skin over the melanoma breaks down and forms an open sore. Both irregular growth and ulceration are hallmarks of melanoma and generally indicate the aggressive nature of the tumor.

Sometimes the melanoma spontaneously regress, either partially or completely. Partial regression may occur due to the immune system recognizing and fighting the tumor cells, yet this does not guarantee a complete cure or prevent the disease from progressing.

Metastasis is the most life-threatening aspect of melanoma. It involves the cancer cells breaking away from the original tumor and spreading to other organs via the lymphatic system or bloodstream. Once metastasis occurs, treatment becomes complex, and the prognosis often worsens.

Staging of Melanoma

Staging of melanoma is used to determine the severity of the disease and the appropriate treatment plan. The stages are:

• Stage 0: melanoma in situ;
• Stage I: melanoma less than or equal to 1 millimeter with or without ulceration or melanoma with a diameter between 1 and 2 mm without ulceration;
• Stage II: diameter between 1 and 2 millimeters with ulceration or greater than 2 mm with or without ulceration but without lymph node involvement;
• Stage III: any tumor thickness with involvement of regional lymph nodes and/or in-transit metastasis;
• Stage IV: distant metastasis.

Always consult a healthcare professional if you notice any changes in your skin or existing moles. Remember, early detection can save lives.