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Rationale: Cases of pseudotumor complicated after THA with metal-on-metal articulation as a bearing surface have been reported. Most of the pseudotumors occurred near or inside the hip joint, and usually have similar features with the infectious condition. We herein report a case of pseudotumor with huge size in the pelvic cavity mimicking features of iliacus muscle abscess. Patients concerns: A 70-year-old female was referred to our emergency department due to huge mass in her right pelvic area on abdominal CT. She complained of mild febrile sensation, generalized weakness, and pain in her right leg for several months. The patient underwent metal-on-metal bearing THA 11 years ago for treatment of right-sided hip pain due to avascular necrosis. Diagnosis: Percutaneous catheter drainage was performed for both therapeutic and diagnostic reasons. No microbes were cultured from the drained fluid, and signs of chronic inflammation were shown on pathology slide samples. The patient showed positive allergic reactions to cobalt and captan on allergic patch test, and serum cobalt levels was increased as 46.78 μg/L (normal value, 0.11–0.64 μg/L). Biopsy samples of the cyst were consistent with the histological findings of pseudotumor reported by Willert et al. Intervention: For the treatment of infection, primarily, the patient was surgically treated by irrigation, debridement, and bone bead insertion. Then, after 4 weeks of antibiotic treatment, revision surgery changing the metal-on-metal articulation into poly-on-metal articulation was performed. Outcomes: CT scan at 1 year after surgery showed no findings of cyst inside the pelvic cavity. Although the patient complained of right sided hip pain (VAS score 2), she was able to perform activities of daily living. Lessons: In patients who underwent metal-on-metal THA, pseudotumor mimicked the feature of periprosthetic infection may occur not only inside the hip joint but also in the pelvic cavity.

Rationale: Galeazzi fractures are uncommon, and are less common in children than in adults. Galeazzi-equivalent fractures, a variant of the classic Galeazzi fractures, mostly occur in children or adolescents. Galeazzi equivalent fractures may commonly accompany distal radial fractures or injury of the epiphyseal plate of the distal ulna.Patient concerns: A 13-year-old man visited our emergency department after stumbling over a rock. Manual reduction and splinting was already done in a nearby medical center. Plain radiographs revealed fractures in the distal radius and fracture of the ulnar epiphyseal plate.Diagnosis: Plain radiographs showed Galeazzi-equivalent fracture. The result of primary closed reduction was not enough and there was still displacement of fracture.Interventions: Anatomical reduction of distal radius was fixed with a plate and screws, and K-wires were inserted percutaneously for reduction and fixation of ulnar fracture.Outcomes: Complete bone union was achieved and normal range of motion is shown 2 years postoperatively. The patient is able to perform daily activities and sport activities without any signs of ulnar growth arrest.Lessons: Open reduction is required in patients with malalignment, failure to reduce the DRUJ or maintain its reduction, or older ages which are hard to expect sufficient bone remodeling.Abbreviations: DASH = the disabilities of the arm, shoulder, and hand, DRUJ = distal radioulnar joint.