Frozen sections are unreliable for the diagnosis of necrotizing soft tissue infections

Intraoperative examination in bone and soft tissue pathology

Intraoperative consultation is a vital tool in bone and soft tissue pathology. Cytologic and histologic interpretation within the clinical, radiologic, and surgical context is crucial for accurate analysis. This review highlights the most significant aspects of this procedure for evaluating musculoskeletal diseases. We outline the process and guide on determining differentiation lines in primary connective tissue neoplasms, assessing malignant potential, evaluating resection margins, investigating metastatic disease, and examining suppurative infections, particularly those associated with prosthetic materials. Furthermore, we summarize additional applications of the procedure.

Time to diagnose and time to surgery in patients presenting with necrotizing fasciitis: a retrospective analysis

BACKGROUND

Necrotizing Fasciitis (NF) is a life-threatening infection characterized by rapid tissue destruction and high mortality. The role of timely diagnosis and surgical intervention in improving patient outcomes remains debated. This study investigates the impact of "time to diagnosis" (TTD) and "time to surgical treatment" (TTS) on the outcomes of NF patients, with a specific focus on the first six hours of critical diagnosis.

METHODS

A retrospective analysis was conducted for patients hospitalized with NF between June 2016 and June 2023. Demographic data, comorbidities, clinical features, treatment, and outcomes were analyzed. The study stratified patients based on TTD (early (≤ 6 h) vs. delayed (> 6 h) and TTS (≤ 6 vs. > 6 h). Outcomes included severity scores, intensive care unit admission, length of stay (LOS), and mortality.

RESULTS

One hundred and twenty-one patients were diagnosed with NF with a mortality rate of 10%. Early diagnosis (≤ 6 h) was associated with lower mortality (5.7% vs. 13.2%) and shorter LOS (17 vs. 27 days) compared to delayed diagnosis. Early diagnosis was associated with a lower Sequential Organ Failure Assessment (SOFA) score compared to delayed diagnosis (p = 0.02). A combined analysis of TTD and TTS revealed that the group with early diagnosis and early treatment (TTD and TTS were ≤ 6 h) had a 3% mortality rate, and 7% of them had a SOFA score > 9. In contrast, delayed diagnosis (TTD > 6 h) was significantly associated with increased mortality, regardless of the TTS.

CONCLUSION

Timely diagnosis within 6 h is crucial for improving outcomes in NF. While early surgical intervention is vital, our findings suggest that the time to diagnosis and subsequent resuscitation efforts may significantly impact survival. This study highlights the importance of optimizing early recognition and diagnosis in the emergency room to reduce delays and improve patient prognosis in NF. Further multicenter studies are needed to validate these findings and refine clinical protocols.

Real-time identification of life-threatening necrotizing soft-tissue infections using indocyanine green fluorescence imaging

Significance

Necrotizing soft-tissue infections (NSTIs) are life-threatening infections with a cumulative case fatality rate of 21%. The initial presentation of an NSTI is non-specific, frequently leading to misdiagnosis and delays in care. No current strategies yield an accurate, real-time diagnosis of an NSTI.

Aim

A first-in-kind, observational, clinical pilot study tested the hypothesis that measurable fluorescence signal voids occur in NSTI-affected tissues following intravenous administration and imaging of perfusion-based indocyanine green (ICG) fluorescence. This hypothesis is based on the established knowledge that NSTI is associated with local microvascular thrombosis.

Approach

Adult patients presenting to the Emergency Department of a tertiary care medical center at high risk for NSTI were prospectively enrolled and imaged with a commercial fluorescence imager. Single-frame fluorescence snapshot and first-pass perfusion kinetic parameters-ingress slope (IS), time-to-peak (TTP) intensity, and maximum fluorescence intensity (IMAX)-were quantified using a dynamic contrast-enhanced fluorescence imaging technique. Clinical variables (comorbidities, blood laboratory values), fluorescence parameters, and fluorescence signal-to-background ratios (SBRs) were compared to final infection diagnosis.

Results

Fourteen patients were enrolled and imaged (six NSTI, six cellulitis, one diabetes mellitus-associated gangrene, and one osteomyelitis). Clinical variables demonstrated no statistically significant differences between NSTI and non-NSTI patient groups (p -value ≥ 0.22 ). All NSTI cases exhibited prominent fluorescence signal voids in affected tissues, including tissue features not visible to the naked eye. All cellulitis cases exhibited a hyperemic response with increased fluorescence and no distinct signal voids. Median lesion-to-background tissue SBRs based on snapshot, IS, TTP, and IMAX parameter maps ranged from 3.2 to 9.1, 2.2 to 33.8, 1.0 to 7.5, and 1.5 to 12.7, respectively, for the NSTI patient group. All fluorescence parameters except TTP demonstrated statistically significant differences between NSTI and cellulitis patient groups (p -value < 0.05 ).

Conclusions

Real-time, accurate discrimination of NSTIs compared with non-necrotizing infections may be possible with perfusion-based ICG fluorescence imaging.

Assessment of Quality of Frozen Section Services at a Large Academic Hospital Before and After Relocation

OBJECTIVES

To determine outcomes following relocation of frozen section services (FSS) and the implementation of a dedicated gastrointestinal frozen service.

METHODS

We reviewed our FSS 6 months prior to and following FSS relocation. Satisfaction surveys were sent to surgeons and pathologists. Survey feedback resulted in a pilot of gastrointestinal subspecialist frozen section coverage.

RESULTS

There were 1,607 and 1,472 specimens from 667 and 602 patients pre- and post-FSS relocation, respectively. There was a decline in median specimen delivery time to pathology (12 vs 10 minutes, P < .001) and an increase in median time from receipt in pathology to intraoperative diagnosis (20 vs 22 minutes, P = .008) in cases with intrapathology consultation but no change without consultation (median, 19 minutes). Intrapathology consultation decreased from 19.7% (317/1,607) to 11.5% (169/1,472) (P < .001). Discordance rates between frozen section and permanent section remained low and similar (2.0% [33/1,607] vs 2.7% [40/1,472], P = .24). There was no significant change in discordance with dedicated gastrointestinal subspecialty frozen section interpretation.

CONCLUSIONS

Relocation of FSS and dedicated subspecialty interpretation may improve surgeon satisfaction but can also create workflow challenges. Pathology departments need to achieve a balance between satisfaction and adequacy to establish best frozen section coverage models.

Regional Variations in Microbiology and Outcomes of Necrotizing Soft Tissue Infections: A Systematic Review and Meta-Analysis

Background: Frequency, microbiology, and outcomes of necrotizing soft tissue infections (NSTIs) could vary across the United States because of differences in locoregional and environmental factors. We synthesized the literature from across the regions of the United States on NSTIs in a systematic review/meta-analysis. Methods: PubMed, ProQuest, Scopus, and Web of Science databases were systematically searched and screened. DerSimonian-Laird random-effects meta-analyses were performed using 'meta' package in R to determine pooled prevalences. Meta-regression analyses examined moderator effects of risk factors. Results: Twenty-seven studies (2,242 total patients) were included. Pooled prevalences of polymicrobial and monomicrobial infections were 52.2% and 39.9%, respectively. The prevalence of monomicrobial NSTIs increased over the last two decades (p = 0.018), whereas polymicrobial infections declined (p = 0.003). Meta-regression analysis showed that most polymicrobial NSTIs were Fournier gangrene (p < 0.001), whereas monomicrobial NSTIs mostly affected extremities (p < 0.001). Staphylococcus aureus was the most common organism isolated (predominantly in the South), followed by Bacteroides spp. (predominately in the East) and Streptococcus pyogenes. Methicillin-resistant Staphylococcus aureus (MRSA) accounted for 11.9% of NSTIs, mainly in the South. The overall mortality rate was 17.8% and declined over last two decades (p < 0.001), with the lowest rate reported in the last decade at 13% without any regional differences. Conclusions: Advancement in the management of NSTIs may have contributed to the observed decline in NSTI-related mortality in the United States. However, the proportion of monomicrobial NSTIs seems to be increasing, possibly because of increased comorbidities affecting extremities. Causative organisms varied by region. Multi-center observational studies are warranted to confirm our observations.

Three Distinct Stroma Types in Human Pancreatic Cancer Identified by Image Analysis of Fibroblast Subpopulations and Collagen

PURPOSE

Cancer-associated fibroblasts have emerged to be highly heterogenous and can play multifaceted roles in dictating pancreatic ductal adenocarcinoma (PDAC) progression, immunosuppression, and therapeutic response, highlighting the need for a deeper understanding of stromal heterogeneity between patients and even within a single tumor. We hypothesized that image analysis of fibroblast subpopulations and collagen in PDAC tissues might guide stroma-based patient stratification to predict clinical outcomes and tumor characteristics.

EXPERIMENTAL DESIGN

A novel multiplex IHC-based image analysis system was established to digitally differentiate fibroblast subpopulations. Using whole-tissue slides from 215 treatment-naïve PDACs, we performed concurrent quantification of principal fibroblast subpopulations and collagen and defined three stroma types: collagen-rich stroma, fibroblast activation protein α (FAP)-dominant fibroblast-rich stroma, and α smooth muscle actin (ACTA2)-dominant fibroblast-rich stroma. These stroma types were assessed for the associations with cancer-specific survival by multivariable Cox regression analyses and with clinicopathologic factors, including CD8⁺ cell density.

RESULTS

FAP-dominant fibroblasts and ACTA2-dominant fibroblasts represented the principal distinct fibroblast subpopulations in tumor stroma. Stroma types were associated with patient survival, SMAD4 status, and transcriptome signatures. Compared with FAP-dominant fibroblast-rich stroma, collagen-rich stroma correlated with prolonged survival [HR, 0.57; 95% confidence interval (CI), 0.33-0.99], while ACTA2-dominant fibroblast-rich stroma exhibited poorer prognosis (HR, 1.65; 95% CI, 1.06-2.58). FAP-dominant fibroblast-rich stroma was additionally characterized by restricted CD8⁺ cell infiltrates and intense neutrophil infiltration.

CONCLUSIONS

This study identified three distinct stroma types differentially associated with survival, immunity, and molecular features, thereby underscoring the importance of stromal heterogeneity in subtyping pancreatic cancers and supporting the development of antistromal therapies.

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

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.

A 5-Year Evaluation of the Implementation of Triple Diagnostics for Early Detection of Severe Necrotizing Soft Tissue Disease: A Single-Center Cohort Study

BACKGROUND

The standardized approach with triple diagnostics (surgical exploration with visual inspection, microbiological and histological examination) has been proposed as the golden standard for early diagnosis of severe necrotizing soft tissue disease (SNSTD, or necrotizing fasciitis) in ambivalent cases. This study's primary aim was to evaluate the protocolized approach after implementation for diagnosing (early) SNSTD and relate this to clinical outcome.

METHODS

A cohort study analyzing a 5-year period was performed. All patients undergoing surgical exploration (with triple diagnostics) for suspected SNSTD since implementation were prospectively identified. Demographics, laboratory results and clinical outcomes were collected and analyzed.

RESULT

Thirty-six patients underwent surgical exploration with eight (22%) negative explorations. The overall 30-day mortality rate was 25%, with an early, SNSTD-related mortality rate of 11% (n = 3). Of these, one patient (4%) underwent primary amputation, but died during surgery. No significant differences between baseline characteristics were found between patients diagnosed with SNSTD in early/indistinctive or late/obvious stage. Patient diagnosed at an early stage had a significantly shorter ICU stay (2 vs. 6 days, p = 0.031). Mortality did not differ between groups; patients who died were all ASA IV patients.

CONCLUSION

Diagnosing SNSTD using the approach with triple diagnostics resulted in a low mortality rate and only a single amputation in a pre-terminal patient in the first 5 years after implementation. All deceased patients had multiple preexisting comorbidities consisting of severe systemic diseases, such as end-stage heart failure. Early detection proved to facilitate faster recovery with shorter ICU stay.