Comparison between organismal staining on histology and tissue culture in the diagnosis of cutaneous infection: A retrospective study.

Abstract

In instances of suspected cutaneous infection, the standard of care includes obtaining skin biopsy specimens for histology and tissue culture. Few studies have compared the clinical utility of each test. To assess the concordance of results between tissue culture and histology, as well as the clinicopathologic features that may influence the diagnostic yield of each test. A retrospective review of all patients who underwent skin biopsy for histology and tissue culture at New York University from 2013 through 2018. Of 179 patients, 10% had positive concordance, 21% had positive tissue culture only, and 7% had positive histology only. We calculated a kappa correlation coefficient of 0.25 between histology and tissue culture (reference, 0.21-0.39 indicates minimal agreement). Histology exhibited higher sensitivity in detecting fungi, whereas tissue culture was more sensitive in identifying Gram-negative bacteria. Antimicrobial use before biopsy led to significantly fewer positive cultures (37.5% vs 71%; P = .023) in patients ultimately diagnosed with infection. This study was conducted at a single institution, thereby restricting its broad applicability. The lack of a validated criterion standard to diagnose infection also limits interpretation of the results. Tissue culture and histopathology often yield discordant results. Dermatologists should recognize specific limitations, yet high clinical utility in special circumstances, of tests when approaching cases of suspected infection.