Skeletal Radiol (2002) 31:240–245 DOI 10.1007/s00256-002-0478-z Received: 9 July 2001 Revised: 27 November 2001 Accepted: 2 January 2002 Published online: 9 February 2002 © ISS 2002 Abstract Myofibromas are mesen- chymal tumors that most often pres- ent in infancy. There are sporadic cases in adults throughout the litera- ture. Myofibroma will demonstrate a variable appearance on CT and ultra- sound, but tends to have a fairly con- sistent appearance on MR imaging. This report describes the MR and sonographic findings as well as the pathologic correlation of a myofibro- ma in the arm of a middle-aged woman. The patient was well, with- out evidence of recurrence 6 months following resection. Keywords Neoplasms, soft tissue · Myofibroma, arm · Magnetic resonance imaging (MRI) · Computed tomography (CT) CASE REPORT Andrew V. Kayes Laura W. Bancroft Gary S. Tennyson Mary I. O’Connor Myofibroma of the upper arm in a 52-year-old woman Introduction In 1954 Stout first described infantile myofibromatosis under the designation of “congenital generalized fibro- matosis.” This benign condition was characterized by the presence of solitary or multiple fibrous nodules in the mesenchymal tissue of newborns [1]. In 1981, Chung and Enzinger reviewed 61 cases of this disorder and pro- posed the term “infantile myofibromatosis” due to the age of onset and histologic features of the tumors [1]. Benign myofibromas normally present as dermal, subcu- taneous, or rarely deep muscle lesions. The vast majority of myofibromas present in children less than 2 years of age. However, similar lesions have been diagnosed in adults. The terms myofibroma and myofibromatosis have been used to describe the solitary and multicentric forms, respectively, with the solitary form being more common. We present the clinical, histologic, and radiographic findings of a deep muscle myofibroma recently diag- nosed in a middle-aged woman at our hospital. While several cases of myofibromas have been reported in adults, they have all been in the subcutaneous tissue, mu- cosal tissue, or bone [2, 3, 4, 5, 6]. To our knowledge, an adult with a deep muscle myofibroma has not previously been reported in the world literature. A.V. Kayes Mayo Graduate School of Education, 4500 San Pablo Road, Jacksonville, FL 32224-3899, USA L.W. Bancroft ( ✉ ) Department of Radiology, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL 32224-3899, USA e-mail: bancroft.laura@mayo.edu Tel.: +1-904-9532149 Fax: +1-904-9532894 G.S. Tennyson Department of Pathology, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL 32224-3899, USA M.I. O’Connor Department of Orthopedic Surgery, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL 32224-3899, USA