Prevalence: accounts for about 10-15% of all cases of melanoma.
Incidence: more frequent in males than females, with a ratio of 2:1. Nodular melanomas occur most often in the fifth or sixth decade.
Site: Nodular melanomas affect any area of skin, but are more often found on the extremities.
Course: Nodular melanoma lesions appear and evolve over months and tend to extend vertically in the skin.
Appearance: Nodular melanoma is most commonly dark brown, red-brown, or red-black and is dome-shaped, polypoid, or pedunculated. It is occasionally amelanotic or flesh colored and resembles flesh-colored dermal nevi or basal cell carcinoma. These amelanotic melanomas represent 2% of all melanomas. Lesions eventually erode, ulcerate and bleed.
Differential diagnosis: Hemangioma which is compressible with its color density changed with firm finger pressure.
Monday, July 21, 2008
What is Nodular melanoma
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5 comments:
I've been reading about the possible risks of sunscreen, particularly with regard to melanoma. Could you consider writing a post about this, evaluating the current state of research? Thanks.
Thank you for interest in my posts.
There are many controversies about the possible risks of sunscreen, particularly with regard to melanoma. However, there are some facts that are worth mentioning.
The “vitamin D story”, in which sun exposure appears to both cause cancer and prevent cancer, is one example where health consumers will need the guidance of health professionals in making an informed decision.
The use of sunscreen with a sun protection factor (SPF) of 8 inhibits more than 95% of vitamin D production in the skin.
The local cellular production of vitamin D acts to regulate cell growth, influences the modulation of the immune system and decrease the risk of the cells becoming malignant. Therefore, measurement of vitamin D is important not only to monitor vitamin D status for bone health, but also for cancer prevention.
More research is needed to better understand the photobiology of vitamin D formation in the skin, and the precise effect of UV radiation on vitamin D synthesis and its role in skin cancer development.
At the same time, there are several published data supporting the fact that skin cancer risk is minimised while taking a precautionary approach to the possible harms of insufficient circulating levels of vitamin D.
The majority of studies found a protective relationship between sufficient vitamin D status and lower risk of cancer. The evidence suggests that efforts to improve vitamin D status, for example by vitamin D supplementation, could reduce cancer incidence and mortality.
Although sunscreens can provide protection against sunburns, its role in skin cancer protection remains a controversial issue. Some, but not all, studies have found an increased risk of cutaneous melanoma with sunscreen use. The most likely explanation is the individuals who use sunscreen tend to stay out longer in the sun, thereby increasing photocarcinogenesis.
Sunscreens are effective in reducing sunburn, but not necessarily the risk of cancer. A study published in April 1992, entitled "Could sunscreens increase melanoma risk?" reported that the greatest increase in melanoma occurred in those regions where sunscreen use is most prevalent. The authors point out that "the SPF of sunscreens concerns solely their ability to absorb ultraviolet B (UV-B) light. Even sunscreens with high SPF factors can be completely transparent to ultraviolet A (UV-A), which includes 90 to 95% of ultraviolet light. UV-A blocking ingredients, which have commonly been added to most sunscreens since 1989, block only half the UV-A spectrum and provide a protection factor against delayed UV-A induced erythema of only 1.7 at usual concentrations. Both UV-A and UV-B have been shown to mutate DNA and promote skin cancers in animals. UV-A also penetrates deeper into the skin than UV-B... two studies suggest that sunscreens may not be effective in preventing skin cancer. A large case-control study showed higher risks of melanoma in men who used sunscreens, and a large prospective study showed a higher incidence of basal cell carcinoma in women who used sunscreens."
Thank you for this very informative response.
Is there any known difference between the protective effects of local cellular production of vitamin D and from supplementation?
sunscreen use impair the vitamin D producing potential of UVB exposure.
vitamin D regulates cell proliferation and differentiation and may thus have an anti-tumour action.
Vitamin D seems to exert a protective effect against common cancers
A clinical study has shown that higher dietary vitamin D intake or use of supplements containing vitamin D is associated with a lower risk of developing some cancers.
There is increasing experimental and epidemiological evidence that local cellular production of vitamin D (resulting from UVR exposure) and/or vitamin D intake or supplementation may be protective for the development of some tumors.
Vitamin D as acquired from the diet or produced in the skin is biologically inactive. It must be metabolized by the liver to produce 25-hydroxyvitamin D3.
The recommended daily requirement for vitamin D3 is 10 micrograms or 400 international units (IU). Higher requirements are reported for the elderly and for rapidly growing adolescents.
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