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Case Report 2: A 75-year-old Irishman presented with a week history of an inflamed thoracic and upper limb area, populated by fragile 3 cm fluid-filled vesicles and flaccid blisters. He had previously been in Dubai where he had seen two dermatologists who had prescribed steroids, anti-inflammatories and Aldara cream. The patient said that the bullae ruptured easily; leaving a reddened base but now they were turning browny black and causing the patient some distress. The patient was a newspaper magnate who was leaving to Toronto that evening. He was otherwise healthy and denied any history of recent infection or trauma. Apparently, recent full blood count and blood chemistry in Dubai was within normal range. He had no other medical problems, except mild diarrhea and was not taking any systemic medications.
On physical examination, there was evidence of numerous bullae containing a clear, yellow fluid along his thorax and in his intertriginous areas. The chest area contained some cloudy and dark yellow bullae mostly the lesions appeared to have a brownish crust at the periphery. Removal of this crust in one instance revealed a moist, red base. There was no surrounding erythema or edema present between the lesions or evidence of regional adenopathy. There was no involvement of the buccal mucous membranes and no
A punch biopsy was taken from the thoracic area to aid in the diagnosis. Histology showed skin with subcorneal bulla formation and overlying parakeratosis. The superficial and mid dermis contained a moderate inflammatory infiltrate composed predominantly of lymphocytes with occasional neutrophils. Gram stain highlighted gram-positive cocci in fragments of detached scale crust.
Based on the clinical findings a provisional diagnosis of bullous impetigo was made. The diagnosis of impetigo is usually based solely on history and clinical appearance. Impetigo is an acute, highly contagious gram-positive bacterial infection of the superficial layers of the epidermis. Bacterial culture and sensitivity are recommended to identify possible methicillin-resistant Staphylococcus aureus (MRSA). Impetigo occurs most commonly in children, especially those who live in hot, humid climates. It presents in two forms: bullous and nonbullous. Nonbullous impetigo is the more common form, constituting approximately 70% of impetigo cases (1) It tends to affect skin on the face or extremities that has been disrupted by bites, cuts, abrasions, other trauma, or diseases such as varicella. (2)
The rarer variant, bullous impetigo is commonly due to exfoliative toxins of S aureus termed exfoliatins A and B. These exotoxins cause a loss of cell adhesion in the superficial dermis, which, in turn, causes blisters and skin sloughing by cleaving of the granular cell layer of the epidermis.(3). It is characterized by fragile fluid-filled vesicles and flaccid blisters and is caused by pathogenic strains of Staphylococcus aureus