Infected von Meyenburg complex causing recurrent gram‑negative septicaemia: the critical diagnostic role of FDG‑PET/CT in a patient with hidradenitis suppurativa.

BACKGROUND: von Meyenburg complex (VMC) is a rare ductal plate malformation, typically presenting as asymptomatic benign intrahepatic biliary microhamartomas. However, when secondarily infected, VMC can become the source of cryptic recurrent septicaemia, posing a substantial diagnostic challenge, particularly in patients with a known history of chronic source of comorbid infection.

CASE PRESENTATION: A 73-year-old man with long-standing hidradenitis suppurativa presented with over ten episodes of recurrent gram-negative septicaemia. Extensive conventional imaging, including a 67Gallium scintigraphy in another hospital, failed to identify an infectious source. Due to persistent diagnostic uncertainty, ¹⁸F-FDG PET/CT was performed. The scan revealed an enlarged liver with heterogeneously increased ¹⁸F-FDG uptake exhibiting an "inverted pyramidal" metabolic configuration: a wide base of activity along the subcapsular dome of superior hepatic segments converged centripetally towards the porta hepatis, thereby casting a tree-like three-dimensional anatomy of the biliary radicles. CT findings were non-specific, showing vaguely scattered mixed densities, greatly outnumbered by the hypermetabolic foci. Constellation of these findings suggests a non-dilated ductal infectious process, leading to the presumptive diagnosis of infected VMC with micro-abscesses. Subsequent MRI/MRCP confirmed numerous tiny T2‑weighted bright signals of varying sizes and intensities in agreement with the "starry sky" pattern of biliary hamartomas. Targeted levofloxacin therapy based on susceptibility testing resulted in resolution of fever and septic parameters. A follow-up ¹⁸F-FDG PET/CT scan three weeks after treatment demonstrated complete metabolic quiescence and resolution of previously documented intrahepatic hypermetabolic foci.

CONCLUSION: ¹⁸F-FDG PET/CT has proven value in investigation for fever of unknown origin. This case illustrates the value of this imaging not only in precise localization of the infectious source but also provides a suggestive metabolic pattern leading to the diagnosis of a rare congenital biliary condition, VMC, as a hidden source of infection otherwise masked by other comorbid infectious foci. Revealing the true source of loculated infection and its mechanism of spread leads to appropriate antibiotic therapy and treatment monitoring.