UPMC Dermatopathology "Case of the Month" Presentations
UPP - Department of Dermatology, Dermatopathology Unit
Case Authors: Carol Roper MD, and Drazen Jukic, MD
JANUARY 2004 CASE OF THE MONTH
DISCUSSION & DIAGNOSIS
Diagnosis:
Porphyria Cutanea Tarda
DISCUSSION
Porphyria Cutanea Tarda is a deficiency
of uroporphyinogen decaroxylase activity, which may be inherited or aquired.
The majority (80%) of cases are nonfamilial. The familial type is inherited
in an autosomal dominant fashion. Risk factors for the sporadic form include
alcohol abuse, hepatitis C, hemochromatosis or iron overload, and chronic exposure
to hepatotoxins such as hexachlorobenzene. Associated conditions include diabetes
mellitus, systemic lupus erythematosus, HIV, and exogenous estrogen use.
Characteristic skin findings occur as described above, on sun-exposed skin.
Sclerodermatous changes may also be present.
Urine contains increased uroporphyin (isomer I), and 7-carboxylic porphyrin
(isomer III). In feces, there is increased isocoproporphyrin.
Histological findings are as above. Additionally, there may be the presence
of caterpillar bodies. These are eosinophillic, PAS-positive globules arranged
parallel to the epidermis in the roof of the blister. They contain degenerating
keratinocytes and basement membrane material. In one study by Fung et al., caterpillar
bodies showed a high specificity for PCT (98%), and a moderate sensitivity (43%).
Solar elastosis may be prominent. The hyalinized material thickening the blood
vessel walls represents redundant basal lamina. Festooning is a term to describe
the retained shape of the papillary dermis as it projects into the bulla. (see:
fig1 & fig2 )
Direct immunofluorescence shows IgG and C3 at the dermoepidermal junction and
in the superficial vascular plexus walls in a linear pattern.
The histologic differential diagnosis as listed by Smoller et al. includes hereditary
and acquired epidermolysis bullosa, pseudoporphyria, penicillamine dermopathy,
cell-poor bullous pemphigoid, traumatic blister, bullosis diabeticorum, and
blisters overlying recent scars.
This patient was treated with phlebotomy and sun avoidance. Antimalarials are
an alternative therapy.
REFERENCES:
Fung M, Murphy M, Hoss D, Berke A, Grant-Kels J. The sensitivity and specificity of “caterpillar bodies” in the differential diagnosis of subepidermal blistering disorders. Am J Dermpath 2003; 25(4): 287-290.
Nordmann Y, Puy H, Deybach J. The porphyrias. J Hepatol Suppl 1999; 30(1): 12-16.
Odom R, James W, Berger T. Errors in metabolism. In: Andrew’s Diseases of the Skin, Ninth Edition, Philadelphia: W.B. Saunders Company; 2000. p653-655.
Smoller B, Kohler S. Subepidermal
vesicular dermatitis. In: Barnhill R, editor. Textbook of Dermatopathology,
New York: McGraw-Hill; 1998. p151-155.
