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CAUSATION & DEVELOPMENT
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BACK
PROCEED 
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Melanoma may arise wherever MELANOCYTES as part of the MELANOCYTIC
SYSTEM are present in the body. The highest melanocyte count can be
found in the skin, where MELANOCYTES are scattered among the surrounding
skin cells at the basal layer of the EPIDERMIS. The EPIDERMIS separates
the outward part of the skin surface from the underlying soft-tissue and
fat layer underneath. In the above skin section sketches, the EPIDERMIS
can easily be recognized by its intense violet tint and its
characteristic saw-like horizontal band structure.
While MELANOCYTES are
loosely distributed among the adjacent epidermal skin cells
(KERATINOCYTES) at the basal epidermal skin layer, they can often be
found as MELANOCYTES CLUSTERS at the bottom tip of the so-called
EPIDERMAL RETE RIDGES (saw-like epidermis protrusions). This is the
location, where MELANOCYTIC NEVI are initially formed through melanocyte
aggregation and cellular maturation. However, if this process does not
work properly, here the formation of pathological MELANOCYTES may begin,
eventually leading to uncontrolled proliferation of atypical and thus
pathologic MELANOCYTES, which is then called MELANOMA.
Can you find the EPIDERMIS?
Can you find the
pathological MELANOMA CELL CLUSTER in the right sketch, indicating the
formation of an early MELANOMA out of PATHOLOGICAL MELANOCYTES? (HINT:
CLICK ON EITHER SKETCH) This is the area, where the pathologist
has to look carefully in a skin biopsy specimen taken, in order to confirm or
rule out a MALIGNANT MELANOMA and to perform a tumor parameter
assessment, which is then called MICROSTAGING.
What causes MELANOMA?
Possible causes for melanoma - as is known to date - are pre-formed
or acquired genetic alterations within the MELANOCYTIC SYSTEM, with
inadequate UV exposure (intermittent high-dose exposure, sunburns)
adversely impacting on regulatory control of melanocyte differentiation.
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