Skin Moles

Any skin mole, by definition, is benign. A skin mole, is a benign proliferation of melanocytes in the epidermis, epidermis and dermis, or dermis alone. In general, a skin mole is a small (less than 6 mm), symmetric, well-circumscribed proliferation of nested melanocytes, and the melanocytes that are deepest in the dermis are smaller than superficial melanocytes, a process known as maturation.

Typical Acquired Mole is a proliferation of nevomelanocytes in the epidermis (junctional), dermis (intradermal), or both areas (compound). The nevomelanocytes forming these lesions often do not demonstrate normal melanocytic differentiation and hence the term nevomelanocytes. The extent of melanocytic proliferation, spectrum and type of differentiation, location of cells, and age of the lesion all may influence clinical and histopathologic features.

The Melanocyte is a melanin-producing cell in the skin, that determines its color. Color is determined by the activity of the melanocytes. Melanin production takes place in melanosomes (tiny sub-structures within the cell). Darkly pigmented skin have melanosomes that contain more melananin.

Melanosomes are a network of microtubules that rearrange themselves within the cell in response to external factors such as ultraviolet rays. Melanosomes usually cluster together near the center of the cell but can rapidly redistribute themselves to the ends of dendritic (tooth-like) processes projecting from the cell. Each melanocyte supplies melanin to approximately 30 nearby keratinocytes via its dendrites along microtubules.

The nevus cell differs from melanocytes in a number of ways. The nevus cell is larger, lacks dendrites, has more abundant cytoplasm, and contains coarse granules. Nevus cells aggregate in groups (nests) or proliferate in a nonnested pattern in the basal region at the dermoepidermal junction. Nevus cells in the dermis are classified into types A (epithelioid), B (lymphocytoid), and C (neuroid). Through a process of maturation and downward migration, type A epidermal nevus cells develop into type B cells and then into type C dermal nevus cells.