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A 63-year-old male with a 15-year history of dia-betes mellitus presented with a poorly healing ulcer on his right heel. He had significant peripheral neuropathy but no evidence of vascular disease. For about 3 years, he had developed recurrent bullous lesions on his feet, which would inexplicably appear in the absence of trauma. The lesions measured anywhere in size from 1-5 cm, frequently involved the plantar aspects of either foot or a 2-3 cm strip along the edge of the feet, were non-tender, and were filled with clear fluid. They would gradually involute, usually leaving no trace, but would occasionally break open exposing denuded epithelium. One of these lesions unfortunately became infected, progressing to a necrotic heel ulcer with underlying calcaneal osteomyelitis, despite attempts at debridement and antimicrobial therapy.
Biopsy of a noninfected bulli on the opposite foot showed only a bullous dermatosis without inflammation. Immunofluorescence stains were negative.
What is this patient’s problem?
Comment by Carol A. Kemper, MD, FACP
About 100 cases similar to this have been described in the literature. While perhaps reasonably well known to dermatologists, this condition is less well known by primary care physicians, podiatrists, and infectious disease specialists. It was first described more than 70 years ago as phlyctenar, meaning "burn-like" blistering. The term "bullosis diabeticorum" was coined in 1967,1 although the etiology remains unknown. Patients with this disorder typically have long-standing diabetes, often with underlying peripheral neuropathy or vascular disease, although the relationship between these conditions and the formation of bullae remains uncertain. Lipsky and colleagues describe 12 such patients during an 8-year period in the Veterans Affairs Medical Center in Seattle, Wash,2 suggesting that this disorder may be more common than suggested by the literature.
The lesions typically present as painless, fluid-filled blisters on the toes, or on the lateral aspects or soles of the feet, without evidence of inflammation, erythema, or induration. They vary in size from a few millimeters to a few centimeters. They usually resolve within 2-5 weeks, often with no residual scarring, unless secondary infection occurs. Males appear to be more commonly affected than females, and, thus far, this disorder has only been described in adults with diabetes.3
The fluid, if aspirated, is proteinaceous and may contain a few polymorphonuclear cells or eosinophils but is sterile. Histopathological examination shows no evidence of immune complex deposition or inflammation, which differentiates these lesions from bullous pemphigoid. There is no consistent pathological finding— some bullae are intraepidermal and others subepidermal.2,4 Cleavage of the tissue layers may occur within the epidermis (either subcorneal or suprabasilar), or subepidermally. There is no evidence of acantholysis. They differ from hemorrhagic (traumatic) bullae, in that the latter show disruption below the dermoepidermal junction and disruption of fibrils.
Treatment should be aimed at keeping the lesions clean and dry, and protected from trauma and infection. Large lesions can be aspirated for comfort. Although they generally heal without complication and little, if any, scarring, they serve as a portal of entry for infection, as unfortunately occurred in this patient.
1. Cantwell AR, Martz W. Arch Dermatol. 1967;96:42-44.
2. Lipsky BA, et al. Int J Dermatol. 2000;39:196-200.
3. Bodman M, et al. J Am Podiatr Med Ass. 1991;81:
4. Basarab T, et al. Clin Exp Dermatol. 1995;20:218-220.