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Porphyria Educational Services

Vol.2 No. 13                                                                                          March 26, 2000
FOCUS:  Sunlight and  the Porphyria Patient                

While some forms of porphyria have definite cutaneous symptomology,
the majority of most porphyria patients note that direct exposure to sunshine and heat does effect them.

During the last year the world hase been introduced to the problem of sunlight and porphyria through media coverage on a young porphyria patient named Travis, and his NASA Space suit.

While most porphyria patients do not have the same type as Travis, nor do they present with severe symptoms as does Travis, all porphyria patients need to be aware of the consequences of too much exposure to direct sunlight. In addition it is most advisable for porphyria patients to avoid exposure to sun and extreme heat.
And what Are the Effects of Sunlight on the Skin? The marked morphologic changes in all parts of the skin, except perhaps the subcutaneous tissue, are recognized as consequences of exposure to UVR.                  

It is precisely through such exposure that these changes underlie the clinically observed sagging, wrinkling, leathery texture, and blotchy discoloration of skin typically associated with actinic damage.                

There does not appear to be any clear cut scale of
how much exposure and how much time is required to effect these changes. However, it is most apparent that clinically normal appearing skin can show pathologic signs of sun damage upon histologic and ultrastructural examination.                

Moreover it has bee cited in chartings that individuals with fair complexions are more susceptible to this damage.

And what about such damage?                

In the epidermis UVR-induced changes there is an aberrant tissue architecture. There are also alterations in keratinocytes and melanocytes.  Moreover there  are functional changes in Langerhans cells

Sun-exposed epidermis becomes thickened as much as twofold compared to sun-protected skin and is disorganized.  There is also demonstrated
evidence of hyperkeratosis, as well as  parakeratosis, and acanthosis.     The keratinocytes lose their typical alignment and progressive flattening.  They also show inclusions in the nucleus. Moreover they  accumulate excessive amounts of melanosome complexes above the  capping or nucleus.                

It has also been found that at the ultrastructural level, clumped keratin filaments and alterations in electron density of some basal cells are characteristic.
Interesting enough few, if any, cytologic changes are noted  in the Keratinocytes. Keratinocytes of the more differentiated epidermal layers .  These of course are the upper spinous, granular, and cornified.                  

In spite of evidence for morphologic change, there are no data indicating altered keratinocyte differentiation as a result of sun exposure.                 In addition , it is not known how UVR interactions with light-absorbing molecules within the keratinocytes (e.g., DNA, keratins, lipids) correlate with the changes in morphology.    Two other cells of the epidermis are also affected by UVR. These are the melanocyte and Langerhans.                    

UVR causes unique dermal damage such as alterations in architecture, matrix composition, vascular structure and function, and cellular activities
                           Sunburn is UVR-induced erythema of the skin caused by vasodilatation of dermal vessels.                    

Generation of the prostaglandins associated with UVB erythema produced within the first 6 to 12 hours can be blocked by topical nonsteroidal
anti-inflammatory agents such as indomethacin. These anti-inflammatory agents, however, cannot inhibit the delayed, post 24-hour erythema. The time-dependent release of varying mediators during the UV-induced inflammatory process underscores the need for further exploration. into selective inhibitors in the       prevention and treatment of sunburn erythema.

Bibliographic resource: Sunlight, Ultraviolet Radiation, and the Skin. NIH Consensus Statement Online 1989 May 8-10 [cited year month day];7(8):1-29.