Abstract:

Histopathological examination to identify infectious organisms is an important diagnostic tool and on rare occasions may be the only means of diagnosis. Here we report a rapidly developing infection of the upper lip. Our patient, a 56-year-old woman with a history of diabetes presented to an outpatient clinic with an upper lip boil treated with acyclovir, which rapidly progressed into an ulcer with crust and necrosis. A punch biopsy highlighted epidermal erosion, suppurative inflammation and numerous microorganisms in a background of myxoid debris. Further examination, in concert with our clinical microbiology team, showed cocci arranged in pairs measuring <1 um2 and bacilli/rods arranged in long chains and singly measuring up to 3 um in length. Furthermore, the bacilli had a 'clearing' under light microscopy. Special stains performed highlighted a mixed population of microorganisms of which the bacilli showed weak staining with Giemsa and PAS and were negative for Gram and GMS stains. Considering the quickly evolving clinical picture, along with microscopic findings of a large bacillus with ‘clearing’, and poor Gram staining; the spore-forming bacterium, Clostridium spp. was a favored contributor to a polymicrobial infection. To our surprise, outside culture grew Klebsiella pneumonia and Streptococcus mitis and oralis which we favor to be background oral contaminant. This case highlights the challenges of accurately classifying microorganisms using H&E sections and special stains even with the expert consultation from clinical microbiologists. For this reason, microbial cultures remain the gold standard, but ultimately the appropriate use of all resources is vital to provide an accurate diagnosis and efficient treatment of the patient.

Financial Disclosure:
No current or relevant financial relationships exist.

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