INTRODUCTION
The porphyrias are inborn errors of metabolism that involve
defects in the metabolism of hemoglobin. There
are at least 8 different types and each has different symptoms,
laboratory abnormalities and treatments.1-2 Although they
are rare, patients with porphyria do present to the dermatologist’s
office. The estimated prevalence of the porphyrias ranges from
less than 10 reported cases worldwide (δ-aminolevulinic acid dehydratase
deficiency porphyria) to 1 per 10,000 people (porphyria
cutanea tarda).1-2 In addition to the various types of porphyria that
can present to the dermatologist, there are several diseases that
can masquerade as porphyria. These include blistering diseases
such as epidermolysis bullosa and pseudoporphyria.
Pseudoporphyria is usually the result of non-steroidal anti-inflammatory
agents. In these patients, removal of the offending
agent results in resolution of the disease. Pseudoporphyria is
not known to be a precursor for any type of porphyria and is not
associated with any other blistering disease. This case report
documents a patient with pseudoporphyria and discusses the
etiology, diagnosis, prevalence, and treatment options.
CASE REPORT
A 66-year-old man presented with a several week history of
blisters on his hands. He stated that the blisters were transient
and non-painful. They were not pruritic nor associated with any
new hobbies or occupations. His family history was negative
for blistering diseases or suggestions of problems consistent
with epidermolysis bullosa, pemphigus, bullous pemphigoid
or any other familial blistering diseases. Upon questioning,
he denied any recent use of photosensitive medications such
as tetracyclines, thiazides or other medications. He was taking
metformin, pioglitazone hydrochloride, valsartan, and atorvastatin.
He denied use of hormones or supplements. When
questioned about use of naproxen sodium, he denied using
this drug. He did, however, relate the fact that he had recently
been using ibuprofen to treat arthritis.
Examination revealed 5-10 mm tense bulla on the dorsum of his
fingers. There was no evidence of milium noted. Office based
evaluation of his urine failed to detect a fluorescent color when
illuminated with blue lights. Initial laboratory examination revealed
normal hemoglobin, hematocrit, and white blood cell
count. In addition, liver functions and electrolytes were within
the normal range.
Biopsies of the bulla were submitted for histologic and immuno-
histologic evaluation (Figure 1). Routine hematoxylin and
eosin staining demonstrated a clear split at the dermal/epidermal
junction. The split was notable for the lack of inflammation
as well as the lack of damage to the epidermal cell layer.
A presumptive diagnosis of pseudoporphyria was made and
the patient was sent for urine porphyrin evaluation. These were
within normal range (Table 1).
DISCUSSION
The porphyrias are related diseases of hemoglobin metabolism.
There are at least 8 types of porphyria, each with a
different defect. Pseudoporphyria is a disease whose symptoms
mimic porphyria, with bulla on the dorsal fingers as
well as milia. In contrast to porphyria cutanea tarda (PCT),
pseudoporphyria is rarely associated with hypertrichosis,
hyperpigmentation, or sclerodermoid change.2-3 Pseudoporphyria
is a rare entity, with less than 100 reported cases.4-5
However, the rarity of this disease may not be accurate and
one author (KB) has seen four cases of pseudoporphyria in
the past four years.
Most frequently, pseudoporphyria is associated with ingestion
of nonsteroidal anti-inflammatory drugs (NSAIDs). The most
likely offender of this category is naproxen sodium.3 However,
other NSAIDS, including ibuprofen, may cause this disease.
Pseudoporphyria has also been associated with ultraviolet A
