N.S. Harshaw1, I.L. Filippone1, Z. Alipour2, Z. Yang2, B.E. King3, J.M. Reichert1, S.K. LaRosa1, K.G. Moore1, L.L. Perea1 3Penn Medicine Lancaster General Health, Department Of Pathology, Lancaster, PA, USA 1Penn Medicine Lancaster General Health, Department Of Surgery, Division Of Trauma And Acute Care Surgery, Lancaster, PA, USA 2University Of Pennsylvania, Department Of Pathology And Laboratory Medicine, Philadelphia, PA, USA
Introduction: COVID-19 is a respiratory disease caused by SARS-CoV-2 which uses the ACE2 receptor for infection. Research suggests that the gastrointestinal manifestations of COVID-19 are due to the presence of ACE2 receptors throughout the gastrointestinal system, including the appendix. Furthermore, there have been a handful of case studies identifying SARS-CoV-2 nucleic acid in appendiceal specimens. The goal of this study was to elucidate a possible relationship between appendicitis and COVID-19 through a histopathological analysis of appendiceal specimens taken from patients who had undergone appendectomy with a coexisting positive PCR (C+). We hypothesized that there would be a strong presence of SARS-CoV-2 nucleic acid in appendiceal samples of those who were C+ at the time of appendectomy.
Methods: We performed a histopathological analysis of 34 appendiceal specimens from patients who had appendectomies following a diagnosis of acute appendicitis between 3/2020 and 6/2022. 25 specimens were from patients who were C+ at the time of appendectomy and 9 were from patients who had a negative SARS-CoV-2 PCR (C-) as controls. 5-micron sections of formalin-fixed paraffin-embedded tissue of each sample were subjected to C4d immunohistochemistry stain. SARS-CoV-2 nucleic acid was measured using RNAscope with a probe (V-nCoV2019-S) against COVID-19, also done with formalin-fixed paraffin embedded tissue. Univariate analyses were conducted and a p-value of < 0.05 was considered statistically significant.
Results: Of the 25 appendiceal specimens coming from C+ patients, only 3 (2 focally, 1 patchy) had presence of SARS-CoV-2 nucleic acid in the specimen (3 C+ v. 0 C-; p=0.553). There was no SARS-CoV-2 nucleic acid present in the 9 C- patients. C4d staining was variable across specimens and had no statistically significant difference between the intensity (p=0.553) or quantity (p=0.188) of the C4d stain between C+ and C- patients. There was also no statistically significant difference between the appendiceal wall thickness between C+ and C- patients (2.28 mm C+ v. 2.11 mm C-; p=0.656; mean wall thickness in mm). Representative images of C4d and COVID-19 RNAscope staining of a C+ patient specimen are shown in Figure 1.
Conclusion: Upon investigation of 25 C+ appendiceal specimens and 9 C- appendiceal specimens, we saw no clinical or statistically significant differences in the presence of SARS-CoV-2 nucleic acid, C4d staining, or wall thickness between C+ and C- specimens. These findings may indicate that the histopathological differences between appendixes from C+ and C- patients are minimal, suggesting that SARS-CoV-2 was not heavily involved with the pathogenesis of appendicitis in the patients studied, unlike was hypothesized.