From: young@serum.kodak.com
Subject: Re: Psoriasis
Originator: young@sasquatch
Reply-To: young@serum.kodak.com
Organization: Clinical Diagnostics Division, Eastman Kodak Company
Date: Fri, 11 Sep 92 22:23:27 GMT

In article <1318@ncrclm.ClemsonSC.NCR.COM> lsnow@ncrclm.ClemsonSC.NCR.COM (Linda Snow) writes:

>In article <1992Sep4.192423.5517@webo.dg.com> mdesai@stealth.webo.dg.com (Munish Desai) writes:
>>
>>  I was wondering if anyone knows about psoriasis:
>>
>>    - what it actually does to the skin

It causes the skin cells to reproduce on a 3-4 day cycle instead of the
normal 30-40 day cycle.  This reproduction rate is not accompanied by a 
matching decrease in cell life span, so thick, scaly lesions form on the
skin.  The increased cellular growth rate is accompanied by an increase in
the local blood supply to support the increased cell reproduction rate, so
the resulting lesions are accompanied by the redness of the increased blood
supply.  The increase in cell reproduction rate should NOT be confused with
cancer, however, since, except for the rate of reproduction, the cells are
(if I recall correctly) indistinguishable from "normal" skin cells.

>>    - cause
>
>I believe it's unknown but involves fat metabolism.

The actual cause is unknown, as far as I can tell, and the connection to
fat metabolism is tenuous at best.  There IS some evidence that a low-fat
diet can ameliorate the symptoms, but whether this is due to a reduction in
fat intake or a reduction of obesity stemming from the reduced fat intake
is not completely clear.  There is a study which documented anomalies in
fatty acid distribution in psoriasis patients, but definitive conclusions
would be premature from this study.

	Vahlquist, C., et. al., The fatty acid spectrum in plasma and
		adipose tissue in patients with psoriasis.  ARCH. DERMATOL.
		RES. 278(2):114-19, 1985.

Some anomalies have also been documented regarding copper, nickel, selenium,
and zinc levels, but it is not clear whether these are causative or a result
or even significant.

There is some evidence that it is an auto-immune disease related to such
afflictions as rheumatoid arthritis.

>>    - any effective treatments or cure
>
>No cure.  Don't know if there are any recent developments as far as
>ameliorative treatments.  My father has had a severe case for almost 50 
>years and has had various treatments none of which were very effective.
>He gets some relief from (A) long soaking baths about twice a week to
>remove scaliness, (b) exposure to sunlight or sunlamp.

Topical and systemic (for more severe outbreaks) glucocorticoids are usually
prescribed for symptomatic relief, and for very severe cases, PUVA and/or the
anti-neoplastic drug methotrexate are sometimes used.  Subcutaneous injections
of glucocorticoids directly into particularly stubborn lesions are often used
as well.

>>    - is it fatal
>

Extremely severe outbreaks which involve major portions of the skin surface
can be life-threatening, but this is extremely rare.

>>    - is it hereditary 
>
>I think there's some evidence for this.  I worried for years that I would
>get it but I'm 46 now and no sign yet.
>
>My personal opinion is that it can be aggravated by stress.

And most practitioners agree that stress CAN be a precipitating factor in
outbreaks.  Skin trauma such as insect bites, rashes, and cuts or scrapes
often result in psoriatic lesions in susceptible individuals.  Outbreaks
also tend to occur during illness and in winter, although whether winter
appearance is due to dryness of atmosphere or lack of sun exposure or some
other factor isn't entirely clear.


-Rich Young (These are not Kodak's opinions.)