Diagnosis: Pyoderma gangrenosum
Pyoderma gangrenosum (PG) is an uncommon, noninfectious neutrophilic dermatosis that results in chronic ulcerative lesions. This disease process favors adult women and can be associated with systemic diseases in the majority of cases. The most common underlying systemic ailments include inflammatory bowel disease, arthritis, infection, and hematologic malignancy; it can also be drug induced.
Typically, the lesions begin as an erythematous pustule or nodule on an extremity. As was the case with our patient, a history of a "spider bite" or other arthropod assault may be elicited in the history as patients try to attribute a cause to the development of the initial ulceration. The pustule then develops into an ulcer with a characteristic necrotic, violaceous undermined border with a purulent base. Also, this disease process is associated with pathergy, in which minor trauma can induce additional lesions at remote sites.
There are four well-known types of pyoderma gangrenosum including the classic ulcerative lesions, pustular, bullous, and superficial granulomatous type, also known as vegetative PG. The pustular type may be seen more frequently in patients with inflammatory bowel disease, the bullous type may predominate in hematologic disorders, and the superficial granulomatous type is known to occur following surgery or other trauma.
The pathology of lesions can be nonspecific. However, in untreated lesions, widespread infiltration of neutrophils can be demonstrated at the base of the ulcers with accompanying necrosis at the periphery of lesions.
Dr. Bilu Martin is in private practice at Premier Dermatology, MD, in Aventura, Fla. More diagnostic cases are available at edermatologynews.com. To submit your case for possible publication, send an email to [email protected].