title: Bilobular calcifying fibrous pseudotumor in soleus muscle: a case report.
abstract: BACKGROUND
  Calcifying fibrous pseudotumor is a rare benign soft-tissue lesion composed of fibrous tissue with abundant hyalinized collagen and dystrophic and often psammomatous calcifications. The cause of the disease is unclear but, usually, complete resection of the well-circumscribed tumor is sufficient to avoid recurrence of the disease. Here, we report an unusual case of this rare tumor that presented as two lobulated lesions in the calf muscle.
  
  
  METHODS
  The patient was a 17-year-old Japanese girl who noted a hard mass in her left calf. Magnetic resonance imaging revealed two well-demarcated lobular masses in the soleus muscle, and the tumor was significantly enhanced by contrast medium. Preoperative differential diagnoses included soft-part tumors composed of fibrous tissue. However, making a definite diagnosis was impossible because a lobulated shape is rare for fibrous tumors. Biopsy demonstrated that the mass was a benign tumor composed of collagen-rich, hyalinized fibrosclerotic tissue. We performed marginal resection of the two nodules, including the fibrous tissue that connected them. Immunohistochemistry was positive for factor XIIIa and negative for anaplastic lymphoma kinase-1. These findings were helpful to distinguish calcifying fibrous pseudotumor from inflammatory myofibroblastic tumor. There was no sign of recurrence at 30 months after surgery.
  
  
  CONCLUSIONS
  To the best of our knowledge, this is the first case of bilobular calcifying fibrous pseudotumor that developed in an extremity. As described in the previous literature, simple excision was sufficient for the treatment of calcifying fibrous pseudotumor with two lobules.
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan. skomiya@m3.kufm.kagoshima-u.ac.jp.
authors.forename: Naohiro
authors.initials: N
authors.lastname: Shinohara
authors.forename: Satoshi
authors.initials: S
authors.lastname: Nagano
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yokouchi
authors.forename: Yoshiya
authors.initials: Y
authors.lastname: Arishima
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Tabata
authors.forename: Michiyo
authors.initials: M
authors.lastname: Higashi
authors.forename: Shinichi
authors.initials: S
authors.lastname: Kitajima
authors.forename: Suguru
authors.initials: S
authors.lastname: Yonezawa
authors.forename: Setsuro
authors.initials: S
authors.lastname: Komiya