EXPERT ANALYSIS AT PDA 2015

PARK CITY, UTAH (FRONTLINE MEDICAL NEWS)According to emerging evidence in the medical literature, Mycoplasma pneumoniae–induced rash and mucositis is a distinct clinical entity with a distinct etiology and a good prognosis.

At the annual meeting of the Pacific Dermatologic Association, Dr. Erin Mathes shared tips on how to distinguish potentially life-threatening causes of rash and mucositis in children. “You want to think about their age, demographics, and history of medication exposures,” said Dr. Mathes, a pediatric dermatologist at the University of California, San Francisco. “Kids are exposed to viruses and bacteria all the time when they’re in day care. Also think about fever, whether or not they’re sick or well appearing, and the morphology.”

According to a retrospective study of 55 children with Stevens-Johnson Syndrome/toxic epidermal necrolysis (SJS/TEN) at the Hospital for Sick Children, Toronto, and Boston Children’s Hospital between 2000 and 2007, the top three causes of these rare conditions were antiepileptic drugs (29%), followed by M. pneumoniae infection (25%) and antibiotics (20%) ( Pediatrics 2011;128[4]:723-8 ).

Dr. Mathes said that she learned from her mentor, Dr. Ilona Frieden, director of pediatric dermatology at UCSF Benioff Children’s Hospital, that in cases of M. pneumoniae-induced rash and mucositis (MIRM), 90% of the disease burden is the mucositis, and the remaining 10% is cutaneous findings. “So when you see mucositis far out of proportion to rash, think Mycoplasma,” Dr. Mathes said.

She and her associates at UCSF conducted a systematic review of all published cases on Mycoplasma-induced rash and mucositis and included 202 cases from 95 reports in the medical literature ( J Am Acad Dermatol. 2015;72:239-45 ). The mean age of patients was 12 years, 66% were male, and most had a mucosal morphology (oral in 94% of cases, ocular in 82%, and genitourinary findings in 63%). “About one-third of patients had mucosal involvement alone, which is important to remember,” she said.

The patients’ skin involvement was generally mild; 46% was considered to be sparse or scattered, and 19% had moderate involvement. Extensive skin involvement “is rare, but it can happen,” Dr. Mathes said. Outcomes for the 202 patients were “generally good,” with 81% having no sequelae. The rates of recurrence and mucosal complications such as scarring around the mouth were both 8%, the rate of pigmentary alterations was 6%, and the rate of mortality was 3%, “but those cases were prior to the introduction of antibiotics in the 1940s,” she emphasized. “Children, in general, are not dying of Mycoplasma-associated rash and mucositis.”

A study published on July 25, 2015 in Pediatrics ( doi:10.1542/peds.2015-0278 ) described an outbreak of eight Mycoplasma-associated SJS cases at Children’s Hospital Colorado, Aurora, that occurred over a 2-month period. In a case-control analysis comparing hospitalized SJS cases with and without evidence of M. pneumoniae infection, the researchers found that cases of Mycoplasma-associated SJS were significantly more likely to have pneumonia (odds ratio, 10), preceding respiratory symptoms (OR, 30), an erythrocyte sedimentation rate of greater than 35 mg/dL (OR, 22.8), and fewer than three affected skin sites (OR, 4.5).

Dr. Mathes was part of a research team that published diagnostic criteria for MIRM. These include less than 10% body surface area affected, involvement of two or more mucosal sites, the presence of few vesiculobullous lesions/scattered atypical targets with or without targetoid lesions, and clinical and laboratory evidence of atypical pneumonia ( J Am Acad Dermatol. 2015;72:239-45 ).

“Rare cases can have more body surface area detachment, or no rash at all,” she said.

Existing tests for Mycoplasma infection are “not that great,” she continued. “It depends on the manufacturer and what is used as the gold standard.” IgM and IgG have specificity ranges from 25% to 100% and sensitivity ranges from 52% to 100%, she said, while polymerase chain reaction is rapidly becoming the gold standard. “That is usually from a nasal wash or bronchoalveolar lavage. It is very sensitive, but is almost too sensitive, because you can actually shed bacteria in your nasal pharynx for 4 months after an infection. That can lead to false positives.”

At UCSF, Dr. Mathes and her colleagues tend to treat MIRM cases with azithromycin followed by supportive care. “We occasionally use steroids but rarely use IVIG [intravenous immunoglobulin],” she said.

Dr. Mathes reported having no financial disclosures.

dbrunk@frontlinemedcom.com

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