Forensic insights into primary pyomyositis: autopsy and post-mortem CT scan based-analysis.

Purpose: To examine the findings of pyomyositis by computed tomography (CT) imaging at autopsy to establish the correct diagnostic approach for this disease in the postmortem setting.

Materials And Methods: A total of 6,964 autopsy cases with CT imaging from two forensic center databases were examined to identify primary pyomyositis. Basic demographics, external findings, postmortem CT findings, and autopsy results were reviewed.

Results: Ten cases of primary pyomyositis were identified. All of the deceased individuals were older than 40 years of age without definitive evidence of human immunodeficiency virus infection. Five individuals had a history of trauma, with one case of trauma occurring more than 1 year previously. Pyomyositis was mostly located in the extremities. Three individuals showed pyomyositis in more than one muscle group. Only one individual showed signs of infection before the autopsy. Three individuals had grossly identifiable erythema. Nine individuals showed positive imaging findings, such as swelling, fat stranding, decreased density, fluid collection, and gas formation, on a CT scan. One individual had no findings of pyomyositis and this was discovered incidentally.

Conclusion: This study shows differences from previous clinical case series of pyomyositis, such as the absence of young age groups and human immunodeficiency virus/acquired immunodeficiency syndrome cases, and a unique case of pyomyositis that occurred more than 1 year after a traumatic incident. Grossly identifiable erythema is rare, posing a considerable diagnostic challenge. However, CT imaging is useful in detecting infection.