By Gary M. White, MD
The patient shown had been on naproxen for 8 months.
The term pseudoporphyria is used when porphria cutanea tarda (PCT)-like lesions arise in the setting of normal porphyrin levels. It usually results from the combination of a weak photosensitizing drug and sun exposure (but it may also occur in the setting of hemodialysis).
- Typical drugs include sulfonamides, dapsone, furosemide, nalidixic acid, naproxen, ibuprofen, pyridoxone, nabumetone, fluoroquinolone antibiotics, or tetracycline.
- Imatinib-induced pseudoporphyria has occurred in both children and adults.
- Oral contraceptives have been reported as well, without serum porphyrins being present.
- Ultraviolet exposure is critical for the development of pseudoporphyria and patients may either be spending significant time in the sun, or visiting a tanning booth.
- As with PCT, vesicles, erosions and fragility on the dorsa of the hands is characteristic although hypertrichosis or hyperpigmentation are typically absent.
- An extremely common offending agent is naproxen which is an over the counter medication widely used for pain control.
- The OTC "detoxification" supplement chlorophyll may induce pseudoporphyria.
Vesicles and fragility on the dorsa of the hands occurs.
A urine porphyrin screen should be performed. The offending agent should be identified and stopped. Sunscreen or sun avoidance are recommended. Unfortunately, the eruption may develop or persist for years after the offending agent is stopped.
One report suggested a list of pain medication that have a low likelihood of inducing pseudoporphyria--diclofenac, indomethacin and sulindac [Cutis 1999;63;223]. For patients with pseudoporphyria associated with dialysis, N-acetylcysteine (600 mg BID or 200 QID) was reported helpful in two patients [BJD 2000;142;560].
Fragility, erosions and Terry's nails in a patient with pseudoPCT on lasix and dialysis.
PseudoPCT from naproxen.
Lesions mostly healed.
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