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Melanocytes are derived from neural crest cells and migrate to the epidermal compartment near the eighth week of gestational age.
Langerhans cells, or dendritic cells, are another cell type in the epidermis and have a primary function of antigen presentation.
These structures are generally formed in the first and second trimesters of fetal development.
These can form a large variety of benign or malignant tumors with diverse biological behaviors.
Melanocytes are also present in normal skin and serve as the source cell for melanoma.
Alternatively, the outer root sheath cells of the hair follicle have also been proposed as the cell of origin for BCC. This is suggested by the fact that BCCs occur predominantly on hair-bearing skin.
BCCs rarely metastasize but can invade tissue locally or regionally, sometimes following along nerves.
Overall, 10% of leukemias and lymphomas have prominent expression in the skin. Epidermal appendages are also found in the dermal compartment.
These are derivatives of the epidermal keratinocytes, such as hair follicles, sweat glands, and the sebaceous glands associated with the hair follicles.