SCAR ECZEMA
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Does anyone here in cyberderm land have an explanation for the development of
eczematous patches near the  base of coronary artery bypass vein graft sites,
usually on the medial aspect, but sometimes all around the base. I see it at all
times of year but with our colder than average winter there seems to be more of
it this year.  I have often wondered if the area was somehow denervated during
the procedure then the dermatitis develops later.  Not an earth shattering topic
but thought someone might have a good explanation. Thanks. 

L.J. Gregg, M.D.
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Since the leg veins are being removed, I wonder if this isn't stasis 
dermatitis developing.

Steve Feldman, MD
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I have an hypothesis: The lymphatics near the vein removal site are 
disrupted. Scarring of the lymphatics causes lymphocyte trapping (just as 
in lymphedema). The trapped/activated lymphocytes are all fired up with 
nothing to do so they attack the overlying skin. The same mechanism is 
the underlying cause of most nummular eczema of the legs. 

Haines Ely 
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That's probably similar to the patches of nummular eczema you get at the site
of perforating veins and on the hand distal to an AV shunt for dialysis, the
mechanism being stasis.

Yelva Lynfield,MD.
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I found a paper by Zuehlke RL, et al describing this phenomenon.  They
coined the term "Dermatitis in loco minoris resistentiae"  to describe
eczematous eruptions in previously injured skin.  
They speculate that this skin may not have normal numbers of adnexa,
vessels, and nerves and may not be of normal thickness.  Also, the
stratum corneum may have a lesser water content and an abnormal
arrangement of corneocytes leading to reduced barrier function,
diminished production of sebum and sweat, decreased perfusion, and
blunted sensation.  

J Am Acad Dermatol 6:1010-1013, 1982.

Keith Schulze, MD
Wharton, TX
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