Vesiculo-Ampollares

Question 1

A 25-year-old male presents with the history of a rash and indigestion for the last 2 months. He tells you that it is very itchy, it comes and goes, looks like blisters, and “breaks out on the back of my elbows and front of my knees.” An exam reveals erythematous, excoriated papules and clusters of small vesicles on the extensor surfaces of his elbows and knees. Which of the following is part of the drug treatment for the suspected condition?

1. Isoniazid
2. Penicillin V
3. Dapsone
4. Thalidomide

Answer 1

3 - Dapsone

• The patient is suffering from dermatitis herpetiformis. Dapsone is a sulfone used in conjunction with gluten avoidance to treat this disease. Gluten avoidance is life-long and is difficult to adhere to. Therefore, patients are best managed in consultation with an experienced dietitian.
• Sulfapyridine, sulphasalazine, and sulphamethoxypyridazine are also used to treat dermatitis herpetiformis.
• The mechanism of dapsone in treating dermatitis herpetiformis is still debated. It is thought to interfere with neutrophil chemotaxis and the respiratory burst. G6PD activity should be checked before starting treatment.

Question 2

A 3-year-old boy with painful swelling and crusted erosions on his face, feet, and hands after one hour’s exposure to springtime sun a few days earlier is evaluated. His mother said he complained of pain within a few minutes after being outdoors, even though she applied sun protection factor (SPF) 50+ sunscreen thickly to all affected sites. He skin was otherwise fully covered by clothing. She said that she first became aware of his extreme sensitivity to the sun when he was a baby. Which of the following is true?

1. A blood test will likely reveal increased protoporphyrins
2. Tests will likely reveal elevated urinary and fecal coproporphyrin
3. The reaction is a contact allergic dermatitis due to the sunscreen
4. SPF 50+ sunscreen only allows 50 minutes in the sun, so was not strong enough to prevent sunburn

Answer 2

1 - A blood test will likely reveal increased protoporphyrins

• Erythropoietic protoporphyria (EPP) is an inherited metabolic disease due to deficiency of ferrochelatase. This results in a build-up of cutaneous protoporphyrin, which causes excessive sunburn-like reaction on exposure to sunlight.
• Abnormal levels of protoporphyrins are found in blood and feces. Unlikely the more common porphyria cutanea tarda, urinary and fecal uroporphyrin and coproporphyrin are normal.
• Symptoms commence within a few minutes of exposure to the sun in EPP, unlike contact dermatitis that takes hours to days to develop. They persist for days or weeks in EPP, unlike solar urticaria which settles within an hour of covering up or going indoors.
• Very high sun protection factor sunscreens (SPF 50+) provide some broad spectrum cover for patients with EPP and may allow longer outdoors before symptoms begin. However, they do not protect well against visible light; the main cause of symptoms in EPP, so severely affected patients are advised to wear mask, gloves and covering footwear when outdoors.

Question 3

A middle-aged patient with alcohol use disorder demonstrates blister formation on sun-exposed areas that frequently ulcerate and ultimately form scars. What is the most likely diagnosis?

1. Pemphigus
2. Erythemia multiforme
3. Poison ivy dematitis
4. Porphyria cutanea tarda

Answer 3

4 - Porphyria cutanea tarda

• Bullous lesions in sun-exposed areas characterize porphyria cutanea tarda (PCT).
• Recognition is important because treatment with phlebotomy is effective.
• Because PCT is a chronic condition, comprehensive management is the most effective means of treatment. Patients should avoid alcohol consumption, iron supplements, and excess exposure to sunlight.
• If present, removing excess iron due to hemochromatosis can be achieved through phlebotomy. Also, if present, hepatitis C treatment is vital to the effective treatment of PCT.

Question 4

A 22-year-old female presents with a history of skin lesions on her elbows. The lesions are very pruritic and uncomfortable. She has tried numerous over-the-counter medications, but nothing has helped. The examination reveals numerous vesicles on the extensor surfaces of both elbows. A biopsy reveals a granular pattern of IgA deposits at the dermal-epidermal junction. What is the most likely diagnosis?

1. Pemphigoid
2. Acne
3. Dermatitis herpetiformis
4. Psoriasis

Answer 4

3 - Dermatitis herpetiformis

• Dermatitis herpetiformis is an immunobullous disorder associated with gluten sensitivity. IgA deposits in the dermal papillae confirm the diagnosis.
• The disorder typically occurs between 20 and 40 years of age and affects men and women equally.
• Patients should be on a gluten-free diet.
• Dapsone and sulfapyridine are the main pharmacologic treatments.

Question 5

A 45-year-old female presents with a 4-month history of a widespread rash and intense itching. Examination reveals a vesiculobullous eruption with annular, crusted, urticated plaques on the trunk and limbs. There is no mucosal involvement. Skin biopsy demonstrates eosinophilic spongiosis with no acantholysis. Direct immunofluorescence reveals epidermal intercellular IgG and C3. What is the most likely diagnosis?

1. Dermatitis herpetiformis
2. Pemphigus foliaceus
3. Bullous pemphigoid
4. Pemphigus herpetiformis

Answer 5

4 - Pemphigus herpetiformis

• Pemphigus herpetiformis (PH) is a rare subtype of intraepidermal autoimmune bullous disease that combines the clinical features of dermatitis herpetiformis and the immunologic characteristics of pemphigus.
• Patients affected with PH usually show erythematous, vesicular, bullous, pustular, or papular lesions, often in a “herpetiform” pattern and with severe pruritus.
• Histopathological features of PH differ from classic pemphigus because of the presence of spongiosis, mostly without acantholysis.
• PH generally has a good prognosis and responds well to dapsone and low doses of corticosteroids.