Getting it Right the First Time: Frozen Sections for Diagnosing Necrotizing Soft Tissue Infections

Abstract

Background The aim of this study was to investigate which histopathologic findings are most indicative for necrotizing soft tissue infections (NSTIs) in ambivalent cases. Methods Patients undergoing surgical exploration for suspected NSTIs with obtainment of incisional biopsies for histopathological assessment were included from January 2013 until August 2019. The frozen sections and formalin-fixed paraffin-embedded (FFPE) samples were retrospectively re-assessed. The primary outcome was the discharge diagnosis. Results Twenty-seven (69%) biopsies of the 39 included samples were from patients with NSTIs. Microscopic bullae (p = 0.043), severe fascial inflammation (p < 0.001) and fascial necrosis (p < 0.001) were significantly more often present in the NSTI group compared to the non-NSTI group. Muscle edema (n = 5), severe muscle inflammation (n = 5), muscle necrosis (n = 8), thrombosis (n = 10) and vasculitis (n = 5) were most frequently only seen in the NSTI group. In thirteen tissues samples, there were some discrepancies between the severity of findings in the frozen section and the FFPE samples. None of these discrepancies resulted in a different diagnosis or treatment strategy. Conclusion Microscopic bullae, severe fascial or muscle inflammation, fascial or muscle necrosis, muscle edema, thrombosis and vasculitis upon histopathological evaluation all indicate a high probability of a NSTI. At our institution, diagnosing NSTIs is aided by using intra-operative frozen section as part of triple diagnostics in ambivalent cases. Based on the relation between histopathologic findings and final presence of NSTI, we recommend frozen section for diagnosing NSTIs in ambivalent cases.

The impact of operative time on the outcomes of necrotizing soft tissue infections: a multicenter cohort study

“…The use of intra-operative diagnostics such as frozen section or Gram stain have also been argued to cause treatment delay, since the time waiting on the results could also be used for debridement, however this statement was not yet investigated in a clinical study [ 24 , 25 ]. This study found indeed a prolonged operative time with a difference in medians of 41 min, which is to be expected since it can take up to 30 min to process and assess a frozen section [ 12 , 13 ]. However, the time to diagnosis was significantly shorter in cases that used intra-operative diagnostics (difference in medians of 3 h), which enables timely debridement.…”

“…NSTI refers to the necrotizing forms of fasciitis, myositis and cellulitis. The NSTI had to be confirmed by either operative findings and/or histopathologic tissue findings and/or microbiology results [ 12 , 13 ]. Patients younger than 18 years at time of onset of the NSTI were excluded, as well were patients who were lost to follow-up after their initial debridement (e.g.…”

Periorbital necrotizing sweet syndrome: A report of two cases mimicking necrotizing soft tissue infections

“…Rapid histopathologic assessment or consideration of use of frozen sections and/or intraoperative gram stain should be considered. 5 Alternatively, if the suspicion for nSS is high and debridement is not pursued, a punch biopsy of adjacent indurated, but non-necrotic skin, may be performed. In typical necrotizing fasciitis ( Fig.…”

Experimental study of different dehydration methods in the process of preparing frozen brain sections

“…(5) Fifty microliters of a rabbit polyclonal antibody against Iba1 (Abcam; ab178846, 1:100) was dropped onto each brain tissue and incubated overnight at 4°C. (6) The tissues were rinsed with PBS buffer for 3 min × 3 times. (The longer the culture time or the thicker the section, the longer the rinse time.)…”