Porphyria Educational Services
PORPHYRIA EDUCATIONAL SERVICES BULLETIN
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.