DermaDiagnosis
What’s Her Dry-agnosis?
This 5-year-old girl's stubborn perioral rash has resisted treatment for months. She has developed a habit of licking her lips, which leaves them...
ANSWER
The false statement is that most melanomas are raised (choice “a”), since most melanomas are essentially macular (flat).
DISCUSSION
Misconceptions about melanomas often delay diagnosis, costing lives. In truth, the majority of melanomas are difficult, if not impossible, to feel on palpation. This is because they arise in the skin, rather than on it.
Malignant melanomas are cancers of melanocytes (the cells that line the basal cell layer). Overexposure to UV sources damages the nuclei of these cells, compromising their ability to repair the damage. This can lead to focally unregulated cell growth.
Initially, this uncontrolled cell replication spreads horizontally. Over time, though, it can grow vertically and penetrate deep enough to invade the vasculature (roughly 1 mm deep), and spread to the liver, lung, or brain. This is why ascertaining the depth of a melanoma is critical for predicting prognosis and determining the extent of additional surgery and search for evidence of metastatic disease.
Melanomas do not typically itch or bleed until they are advanced (if at all). And most arise de novo (as new lesions, rather than pre-existing). So, contrary to popular belief, moles rarely turn into melanomas.
It is also true that approximately 80% of all melanomas arise on skin normally covered by clothing, despite the role of sunlight in the development of melanoma. For reasons not totally understood, the combination of fair, sun-intolerant skin and periodic intense exposure predisposes to skin cancer—clothing notwithstanding.
