Acute Interstitial Inflammation on Skin Biopsies and Positive Tissue Cultures in Cellulitis Patients Are Associated a Worse Prognosis.

Background: Cellulitis is a significant public health burden and lacks a gold standard for diagnosis. Up to 1/3 of patients are incorrectly diagnosed. The skin biopsy has been proposed as the gold standard.

Objective: In this study, we evaluate the histopathologic characteristics and tissue culture positivity of biopsies in patients diagnosed with cellulitis seen by our inpatient dermatology consultation service.

Methods: This retrospective cohort study examined patients who were hospitalized with a skin and soft tissue infection at our institution between 2011 and 2020 and underwent a skin biopsy.

Results: Those with a positive tissue culture were more likely to die within 30 days compared with those with negative tissue cultures (26% vs. 6%, P = 0.048). Patients who died within 30 days were more likely to have acute interstitial inflammation as a feature on histopathology (38%, P = 0.03).

Limitations: Single institutional design, unintentional exclusion of patients with organism-specific diagnosis, and selection for a medically complex patient population because of the nonroutine collection of biopsies.

Conclusion: Positive tissue cultures and histopathology showing acute interstitial space inflammation on skin and soft tissue infection (SSTI) biopsies are associated with increased mortality and thus may serve as indicators of poor prognosis.