Race for the Case answers

Diagnose this new case by Chiara Rosenbaum, DO, MS

A 60-year-old male with past medical history of diabetes mellitus type 2, deep venous thrombosis/pulmonary embolism, hypertension, pancreatitis, stroke, hyperlipidemia, and history of necrotizing fasciitis presented to the hospital with a chief complaint of blisters on his hands. The patient noticed new blisters on both hands a week prior, and he admits to associated pain and swelling of the bilateral hands. He denies pruritus or having blisters elsewhere on his body. The patient denied recent illness, travel, new medications, working outdoors or in hazardous conditions, or recent trauma to the hands. The patient reports taking a daily over-the-counter anti-inflammatory medication for pain associated with his chronic pancreatitis.

1. What is the most likely diagnosis?
Answer: Pseudoporphyria.

2. How would you differentiate this condition from a similar inherited form?
Answer: Serum and urine (and fecal) porphyrin studies are normal in this condition, whereas they are elevated in true porphyria cutanea tarda (PCT). Clinically, PCT demonstrates hypertrichosis, sclerodermoid changes, and hyperpigmentation, whereas pseudoporphyria generally lacks these findings.

3. Describe the classic histopathologic findings of this condition.
Answer: Cell poor subepidermal vesicle with festooning (projection of the dermal papillae into the blister cavity) and caterpillar bodies within overlying epidermis.

4. What is the relevant work-up for this condition?
Answer: Plasma, urine, and stool porphyrins. Thorough drug history. CBC, CMP, hepatitis panel, and HIV testing.

5. What medication is most likely to have caused this patient’s episode?
Answer: Naproxen (NSAIDs are a common culprit)