A Rare Case of Retroperitoneal Tumefactive Fibroinflammatory Lesion Related to IgG4-Sclerosing Disease.

We present a unique case of a retroperitoneal tumefactive fibroinflammatory lesion related to IgG4-sclerosing disease; it is a rare manifestation of the IgG4-related disease, which usually causes diffuse fibrosis when located in the retroperitoneum, rather than mass-like lesions. A 49-year-old man presented to the emergency department complaining of abdominal pain and vomiting. Subsequent testing with abdominal ultrasound, CT, and MRI revealed a large retroperitoneal mass of unknown origin, heterogenous, with a concentric circles pattern best visualized in MRI. The lesion was resected, and the histological and immunohistochemical studies revealed an IgG4-related tumefactive fibroinflammatory lesion of the retroperitoneum.

An unusual case of an extensive post-injection retroperitoneal abscess in an intravenous drug user.

Retroperitoneal abscesses constitute an uncommon, complex, and life-threatening intra-abdominal infection. The insidious nature of the presentation, coupled with the presence of non-specific clinical symptoms, might result in misdiagnosis or delayed diagnosis, ultimately contributing to substantial morbidity and mortality. Herein we report a case of a 32-year-old intravenous drug user who presented to the emergency department complaining of high-grade fever, intense hiccough, and back pain due to retroperitoneal abscess formation after intravenous injection in the left femoral vein.