A 33-year-old woman comes to the office due to blistering on the backs of her hands. She has had occasional blisters in the past, but numerous lesions appeared last week after she spent some time outdoors gardening. The lesions are not painful but are associated with mild itching. The patient says her skin is also fragile and trivial trauma has caused superficial erosions that heal with scarring. She occasionally drinks alcohol but does not use tobacco. The patient used injection drugs in the past but stopped after being diagnosed with hepatitis C infection 8 years ago. She has not yet received treatment for hepatitis, and her only medication is a daily oral contraceptive. Vital signs are within normal limits. Physical examination shows several vesicles and erosions on the dorsum of both hands. Some of the lesions are healing with crusts and scars. Which of the following is the most likely underlying cause of this patient's skin lesions?

Question

A 33-year-old woman comes to the office due to blistering on the backs of her hands.  She has had occasional blisters in the past, but numerous lesions appeared last week after she spent some time outdoors gardening.  The lesions are not painful but are associated with mild itching.  The patient says her skin is also fragile and trivial trauma has caused superficial erosions that heal with scarring.  She occasionally drinks alcohol but does not use tobacco.  The patient used injection drugs in the past but stopped after being diagnosed with hepatitis C infection 8 years ago.  She has not yet received treatment for hepatitis, and her only medication is a daily oral contraceptive.  Vital signs are within normal limits.  Physical examination shows several vesicles and erosions on the dorsum of both hands.  Some of the lesions are healing with crusts and scars.  Which of the following is the most likely underlying cause of this patient's skin lesions?

Quizplus · Accepted Answer

11ec25c8_d385_f047_bc81_3be1b0780bff_MD0003_00 This patient with dermal blisters on the hands and untreated hepatitis C has typical features of porphyria cutanea tarda (PCT). The porphyrias are hereditary or acquired disorders of heme synthesis. Enzyme deficiencies in the early steps of porphyrin synthesis (eg, acute intermittent porphyria) cause abdominal pain and neuropsychiatric manifestations (eg, psychosis, neuropathy); abnormalities in the later steps (eg, PCT) lead to photosensitivity due to accumulation of porphyrinogens that react with oxygen on excitation by ultraviolet light. PCT is due to deficiency of uroporphyrinogen decarboxylase and is the most common porphyria. PCT is characterized by painless blisters that heal with scarring, increased skin fragility on the dorsal surfaces of the hands, facial hypertrichosis, and hyperpigmentation. It can be triggered by ingestion of certain substances (eg, ethanol, estrogens) and is most common in patients with underlying hepatitis C. Elevated plasma or urinary porphyrin levels confirm the diagnosis. Phlebotomy or hydroxychloroquine may provide relief, as can treatment for hepatitis C. blisters hyperpigmentation (Choice A) Allergic contact dermatitis is characterized by pruritic plaques and vesicles on exposed skin. Skin fragility with erosions and scarring is not typical. (Choice B) Impetigo is caused by Staphylococcus aureus or group A streptococcus and is characterized by pruritic, honey-colored macules, vesicles, and bullae on the face or other exposed parts. It would be unlikely to affect both hands symmetrically. (Choice D) Herpes zoster causes painful vesicular lesions clustered unilaterally in a dermatomal distribution. (Choice E) Dermatitis herpetiformis represents an autoimmune reaction (with subepidermal anti-transglutaminase IgA autoantibodies) triggered by dietary gluten. It is characterized by intensely pruritic papules and vesicles on the elbows, knees, buttocks, posterior neck, and scalp. (Choice F) Mixed cryoglobulinemia associated with hepatitis C is due to immune complex deposition in small blood vessels, leading to endothelial injury and end-organ damage. Typical manifestations include palpable purpura, arthralgias, and glomerulonephritis. Educational objective: The porphyrias are disorders of heme synthesis. Porphyria cutanea tarda, the most common porphyria, is due to deficiency of uroporphyrinogen decarboxylase. It can be triggered by the ingestion of ethanol or estrogens and is frequently associated with hepatitis C. Manifestations include photosensitivity with blisters and skin fragility. References: Porphyria cutanea tarda as the most common porphyria. (http://www.ncbi.nlm.nih.gov/pubmed/18093456)

A 33-Year-Old Woman Comes to the Office Due to Blistering