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 dermatologistâ€™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.
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).
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