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During a medical mission trip to Africa a child was seen with pyoderma gangrenosum on the dermatology ward of a hospital. She has had a long history of pyoderma gangrenosum with ulcerations on her face, neck, and chest (Figure 149-1). The scarring has caused adhesions between the face, neck, and chest.
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Pyoderma gangrenosum (PG) is an uncommon ulcerative disease of the skin of unknown origin that affects both children and adults. It is a type of neutrophilic dermatosis.
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PG occurs in approximately 1 person per 100,000 people of all ages each year.1
Children account for only 3 to 4 percent of the total number of cases. There is nothing clinically distinctive about pyoderma gangrenosum in children and adolescents other than the age of the patients.2
No racial predilection is apparent.
A slight female predominance may exist.
Predominately occurs in fourth and fifth decade, but all ages may be affected.
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Etiology and Pathophysiology
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Etiology is poorly understood.
Pathergy (initiation at the site of trauma or injury) is a common process and it is estimated that 30 percent of patients with PG experienced pathergy.1
Up to 50 percent of all cases are idiopathic.3
At least 50 percent of cases are associated with systemic diseases such as inflammatory bowel disease, hematologic malignancy, and arthritis.3
It occurs in up to 5 percent of patients with ulcerative colitis and 2 percent of those with Crohn disease (Figure 149-2).4,5
In one study of 46 patients 18 years of age or younger with pyoderma gangrenosum, an underlying systemic disease was present in 74 percent of the older children, and as in adults it was most commonly ulcerative colitis.2
The lesions tend to affect the lower extremities (Figure 149-3), but infants tend to have ulcers more commonly than adults in the genital and perianal distribution, 6 the head and face (Figure 149-1), and the buttocks (Figure 149-4).7
Biopsies usually show a polymorphonuclear cell infiltrate with features of ulceration, infarction, and abscess formation.
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