TORONTO — The presentation of vasculitis in a child may be complicated when the patient has coexisting strep A infection. Taking time to sniff carefully can lead to the correct diagnosis and treatment, Dr. Miriam Weinstein said at the annual conference of the Canadian Dermatology Association.
She described the case of an otherwise healthy 10-year-old boy who presents with an urticaria-like skin eruption of edematous plaques over his entire body and face. Each lesion persists for more than 24 hours and then resolves completely. He also has fever, abdominal pain, and vasculitis of the small to medium arteries. He has had 10 episodes, each lasting approximately 10 days, in the last 3 years. Differential diagnosis included leukocytoclastic vasculitis, but that condition is rare, with no clear reports in the literature. Poly-arteritis nodosa was another consideration, although this patient did not have the painful, tender nodules that are often associated with this condition.
The cutaneous form of poly-arteritis nodosa (cPAN) primarily affects the skin without systemic involvement such as vasculitis. Microscopic PAN (mPAN), in contrast, often affects small arteries and veins and can feature lung and kidney involvement. “These are different conditions, but they may be part of a spectrum—from mPAN to PAN,” said Dr. Weinstein, medical director of the pediatric dermatology fellowship program at the Hospital for Sick Children in Toronto.
A skin biopsy in this case indicated neutrophilic vasculitis with inflammation.
“Group A strep was cultured from his throat when I saw him on the tenth eruption,” Dr. Weinstein said. His throat swab findings were negative between episodes.
Determination of the precise diagnosis was challenging. “He had a recurrent strep infection. This case involved urticarial eruption, which is uncommon with strep. He also had some features consistent with mPAN … vasculitis of small to medium arteries,” Dr. Weinstein said.
The final diagnosis was group A β-hemolytic streptococci-induced mPAN with urticarial lesions.
Group A strep infection is often mistaken for Candida, irritant contact dermatitis, or seborrheic dermatitis. It is often treated but persists, Dr. Weinstein said. Frequently there is an odor with group A strep infection that is not present with Candida.
“Don't forget perianal strep. It is more common than reported and often missed,” she said. This usually affects patients younger than 10 years. If asked, these kids will have a history of painful bowel movements and perianal itch.
“Often the parents don't know about this. It is the first time it's asked,” Dr. Weinstein commented.
Both Candida and group A strep can induce psoriasis. Strep is a well-known inducer of psoriasis and psoriasislike conditions. Psoriasiform infectious disease features widespread, acute, well-demarcated, and erythematous plaques with scale. “There are no reports of this in the literature, but many pediatric dermatologists see this,” she said.
Throat swabs were negative between eruptions of a recurrent group A strep infection with vasculitis.
The child's recurrent group A streptococcus infection with vasculitis was diagnosed on histology findings (above). Photos courtesy Dr. Miriam Weinstein