Acute appendicitis is a common cause of acute abdominal pain but is rare in infants because of anatomical and physiological characteristics that reduce the risk of the luminal obstruction of the appendix. However, when it occurs in infants, it is often difficult to diagnose clinically and may progress rapidly to a fatal outcome. We report a forensic autopsy case of an 11-month-old infant who died 2 d after developing fever and decreased oral intake, without antemortem diagnosis. Autopsy revealed fibrinous ascitic fluid and an edematous, dark-red appendix with fibrin deposits, but no macroscopic luminal obstruction or perforation. Histopathological examination showed diffuse inflammatory cell infiltration and hemorrhage across all layers of the middle and peripheral portions of the appendix, along with lymphoid hyperplasia in the middle portion. Intestinal bacteria were detected in the ascitic fluid. The cause of death was identified as acute appendicitis with subsequent generalized peritonitis. Although luminal obstruction is a common cause of appendicitis, it was not observed macroscopically in this case. However, histopathological findings suggested that lymphoid hyperplasia in the middle portion of the appendix caused luminal narrowing and impaired circulation in the appendiceal wall, triggering appendicitis. This case demonstrates that infantile appendicitis can be fatal even without perforation and highlights the potential role of lymphoid hyperplasia in the pathogenesis. It also underscores the importance of considering appendicitis in the differential diagnosis of infants with nonspecific symptoms and illustrates the value of postmortem histopathological investigation in elucidating the disease mechanism.

RNAemia, defined as the presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA in blood, is correlated with the severity of coronavirus disease 2019 (COVID-19). Although serum or plasma is commonly used for viral RNA extraction in clinical studies, separating serum in forensic postmortem specimens is often difficult because of postmortem changes. This study aimed to establish an efficient method for extracting SARS-CoV-2 RNA from postmortem whole blood and assess its forensic applicability using actual case specimens. Three extraction methods-acid guanidinium thiocyanate-phenol-chloroform (AGPC), spin column (SC), and magnetic bead method-were compared to identify an efficient approach for SARS-CoV-2 RNA extraction from whole blood. The AGPC method yielded the highest viral RNA recovery, although reproducibility was limited. We therefore evaluated a modified AGPC-SC method, in which whole blood was homogenized, subjected to AGPC phase separation, and purified using the SC method. This procedure maintained the yield of viral RNA while improving reproducibility. The optimized method showed a positive percent agreement of 85.3% and a negative percent agreement of 92.5% for postmortem whole blood samples from COVID-19 cases compared with serum. Whole blood and serum viral RNA loads were strongly correlated (Spearman's ρ = 0.9014), with a small mean difference on Bland-Altman analysis (-0.053 log₁₀ copies/µL). Thus, postmortem whole blood may serve as an alternative to serum, and the AGPC-SC method involving homogenization provides a practical approach for SARS-CoV-2 RNA extraction in forensic practice.