title: Chronic expanding hematoma with a significantly high fluorodeoxyglucose uptake on ¹⁸F-fluorodeoxyglucose positron emission tomography, mimicking a malignant soft tissue tumor: a case report.
abstract: BACKGROUND
  Chronic expanding hematoma is a rare persistent hematoma that can sometimes be misdiagnosed as a malignant tumor due to its clinical and radiological features.
  
  
  METHODS
  A 42-year-old Japanese man with a large mass in his leg, suggestive of malignancy, presented to our hospital. He had been aware of the leg swelling for the last eight years. A magnetic resonance imaging scan demonstrated a large mass with two components. One was a large, well-defined cystic mass (13×9cm) showing high intensity on T1- and T2-weighted images, and the other was a solid mass (3.5×2.5cm, adjacent to the large mass) with high intensity on T1-weighted images. Two-[18F]fluoro-2 deoxy-D glucose positron emission tomography images revealed increased uptake with a maximum standardized uptake value of 15.8 in the solid mass. As these findings were considered suggestive of hematoma associated with a malignant lesion, an open biopsy was performed. A pathological examination demonstrated a hematoma with xanthogranuloma, and no malignant cells were evident. Therefore, we resected the tumor including both components, and the histological diagnosis was chronic expanding hematoma. Clinical diagnosis based on 2-[18F]fluoro-2 deoxy-D glucose uptake is sometimes limited by the fact that 2-[18F]fluoro-2 deoxy-D glucose is taken up by not only malignant tumor cells but also macrophages and tissues with granulation or inflammation.
  
  
  CONCLUSIONS
  Significantly increased standardized uptake value in the peripheral rim of the lesion on 2-[18F]fluoro-2 deoxy-D glucose positron emission tomography imaging, mimicking a soft tissue sarcoma, should be recognized as a potential diagnostic pitfall in cases of chronic expanding hematoma.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Nishida
authors.affiliation: Department of Musculoskeletal Oncology, National Cancer Center Hospital, 5-1-1 Tsukiji, Chuo-ku 104-0045, Tokyo, Japan. ekobayas@ncc.go.jp.
authors.forename: Eisuke
authors.initials: E
authors.lastname: Kobayashi
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kubota
authors.forename: Nokitaka
authors.initials: N
authors.lastname: Setsu
authors.forename: Koichi
authors.initials: K
authors.lastname: Ogura
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Tanzawa
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Nakatani
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Kato
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Chuman
authors.forename: Akira
authors.initials: A
authors.lastname: Kawai
mesh_terms: D000328:Adult; D001706:Biopsy; D003937:Diagnosis, Differential; D019788:Fluorodeoxyglucose F18; D006406:Hematoma / Q000000981:diagnostic imaging* / Q000601:surgery; D006801:Humans; D007866:Leg; D008279:Magnetic Resonance Imaging; D008297:Male; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals; D012509:Sarcoma / Q000000981:diagnostic imaging
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18