Damian McNamara

March 13, 2013

MIAMI BEACH, Florida — Shrewd clinical judgment by a dermatologist consultant changed an initial diagnosis of cellulitis for nearly three-quarters of inpatients admitted to academic medical centers, a new study shows.

Although it's important to catch all cases of cellulitis, a common and potentially serious skin infection, "misdiagnosis of cellulitis is truly a significant problem in the inpatient population," said Lauren Strazzula during a late-breaking research session that garnered a lot of interest here at the American Academy of Dermatology (AAD) 71st Annual Meeting.

"Not only can inpatient dermatology consultation identify and treat these mimickers of cellulitis, but we believe it may be able to decrease hospital admission rates for cellulitis, decrease length of stay, decrease unnecessary antibiotic use, and therefore decrease healthcare costs," said Strazzula, a medical student at the University of Massachusetts Medical School in Boston.

The researchers reviewed the charts of more than 1400 inpatient dermatology consults from the Massachusetts General Hospital in Boston, the University of Alabama in Birmingham, and the University of California at San Francisco and Los Angeles. Cellulitis comprised 75 or 5% of these consultations.

Identifying factors to help clinicians distinguish between patients with cellulitis and so-called pseudocellulitis was the study's aim. Unfortunately, no patient demographics or risk factors commonly associated with cellulitis — including history of skin disease, active cancer, diabetes, or immunosuppression — emerged as statistically different between these groups.

"Inpatient dermatology consultation is crucial in this population," Strazzula told Medscape Medical News. "Our take-home message is that the vast majority of patients who a dermatologist will see on the consult service for the evaluation of cellulitis will instead have another cutaneous condition."

Wrong Cutaneous Condition

Stasis dermatitis was the most common alternative diagnosis in 32% of patients, followed by contact dermatitis (14%) and inflammatory tinea (9%).

Based on the final diagnosis by the dermatology team, 75% of the patients were diagnosed with pseudocellulitis and therefore initially misdiagnosed with cellulitis. "We knew this was a big problem encountered in the inpatient setting, but we did not realize how significant it actually was," Strazzula said. "We were pretty blown away by this statistic since it is more than double what has previously been reported."

For example, in a prospective study, 28% (41 of 145 patients) admitted to hospital and evaluated by a dermatologist or infectious disease specialist had a different skin disorder, most commonly stasis dermatitis ( Dermatol Online J. 2011;17:1). The only statistically significant difference they found between patients with cellulitis vs pseudocellulitis was the proportion with leukocytosis, 55% vs 24% (P = .001).

In another, retrospective study of 196 inpatient dermatology consultations, 33% (7 of 21 patients) consulted for cellulitis instead had a cutaneous mimicker ( J Am Acad Dermatol. 2010;62:518-519).

In the current study, although there was some variability in the misdiagnosis rate between institutions (62.5% to 87.5%), the differences among them was not statistically significant. This provided validity to their overall misdiagnosis rate, Strazzula said.

When asked to comment by Medscape Medical News, Laurel Schwartz, MD, from Thomas Jefferson University in Philadelphia, Pennsylvania, said, "I have to say it's nice to see the study conclusions confirm our experience as inpatient dermatology consultants, despite the limitations of being retrospective and a relatively small sample size. As academic general dermatologists at our institution, we cover inpatient consultations, and have also informally found that there are a broad range of diagnoses misinterpreted as cellulitis by requesting inpatient physicians."

Dr. Schwartz said she agrees that stasis dermatitis is a relatively common mimicker, but said she also has encountered less common presentations like erythema nodosum and clotting diseases initially diagnosed as cellulitis.

Systemic Fungal Infection

"One recent consultation called in as cellulitis turned out to be a very serious systemic fungal infection and dermatology consultation played the critical role in providing the correct diagnosis and initiation of life-saving treatment," Dr. Schwartz said.

"As this report nicely quantifies in the case of inpatient consultation for cellulitis, those institutions and patients lucky enough to have access to a dermatology consultative service are likely to reap the rewards of a skin expert's diagnosis," she said.

The retrospective design and the sample size — with only about 5% of identified consults for cellulitis — are potential study limitations, Strazzula acknowledged. Generalizability is another concern, she added, "We understand inpatient dermatologists are not available at all institutions." In addition, only those patients admitted with cellulitis and who had a dermatology consult were included in the analysis.

A randomized controlled trial is under way at Massachusetts General Hospital to continue this research and further assess the effectiveness of the inpatient dermatology service for patients admitted for cellulitis. Another future endeavor might emerge from identification of the most common mimickers in the current study.

Strazzula said, "We could launch an educational campaign for emergency medicine and internal medicine colleagues…so they too might be better able to distinguish these two populations."

The investigators and Dr. Schwartz have disclosed no relevant financial relationships.

American Academy of Dermatology (AAD) 71st Annual Meeting. Late Breaking Research presented March 2, 2013.