Various oral medications including nonsteroidal anti-inflammatory drugs (
NSAIDs) have been associated with pseudoporphyria, although the pathogenetic basis has not been elucidated. A novel
NSAID nabumetone (
Relafen) has become popular because of its minimal gastrointestinal side effects. Its association with pseudoporphyria is not reported save for its listing in the Physician's Desk Reference (PDR) as a possible side effect. Biopsies of lesional skin from 4 patients manifesting
blisters and erosions on the hands and face within 4 months of starting
nabumetone were submitted for light microscopic and immunofluorescent (IF) studies. Histories and serology were obtained. Two patients had
rheumatoid arthritis (RA), 1 had
mixed connective tissue disease (
MCTD), and 1 received
diltiazem. All 4 had
antinuclear antibodies. Characteristic clinical, light microscopic and IF features in the absence of elevated urine
porphyrin levels confirmed a diagnosis of pseudoporphyria in all 4 patients. Biopsies in three patients showed features attributed to underlying
connective tissue disease (CTD), including
ectasia of the superficial vascular plexus, mild
leukocytoclastic vasculitis, superficial and deep perivascular lymphocytic infiltrates with dermal
mucinosis, granular deposition of
IgM along the dermoepidermal junction indicative of a positive lupus band test, and of
IgG and
C5b-9 within keratinocytes.
Nabumetone (
Relafen) can provoke pseudoporphyria; an underlying CTD
diathesis may be a predisposing factor.