J Korean Soc Radiol.  2017 Feb;76(2):142-147. 10.3348/jksr.2017.76.2.142.

Mammary-Type Myofibroblastoma of the Buttock: A Case Report and Review of the Literature

• Park JM
• Yi J

• KMID: 2367862
• DOI: http://doi.org/10.3348/jksr.2017.76.2.142

Abstract

Mammary-type myofibroblastoma is a very rare, benign mesenchymal tumor consisting of spindle-shaped cells along with thick hyalinized collagen bundles and an intralesional fat component; its histopathological features are identical to those of myofibroblastomas of the breast. It usually occurs along the embryonic milk-line; however, unusual cases occurring outside of the embryonic milk-line have also been reported. Although this tumor always shows clinically benign behavior, its variable histological composition can easily be confused with many other fibrous and lipomatous neoplasms. Unfortunately, its radiological findings are extremely rarely described in the literature. Here, we present a rare case of mammary-type myofibroblastoma in a 38-year-old woman who presented with a well-circumscribed solitary mass in the buttock, and discuss various radiologic imaging findings, such as plain radiography, ultrasonography, and magnetic resonance imaging results.

MeSH Terms

Adult
Breast
Buttocks*
Collagen
Female
Humans
Hyalin
Magnetic Resonance Imaging
Neoplasms, Muscle Tissue*
Radiography
Ultrasonography
Collagen

Figure

• 

  Fig. 1 Mammary-type myofibroblastoma of the buttock in a 38-year-old woman. A. Oblique plain pelvic radiograph showing a well-defined, oval, soft tissue mass in the left buttock. B. Ultrasound scan showing a well-defined, echogenic mass with heterogeneous echotexture and variable posterior acoustic shadowing in the subcutaneous layer of the left buttock. C. T1-weighted magnetic resonance image in the axial plane showing a hypointense mass with a small area of intralesional fat (arrow) in the left buttock. D. T2-weighted image with fat saturation in the axial plane demonstrating a well-circumscribed mass with heterogeneous hyperintensity and internal low signal intensity. E. Axial contrast-enhanced fat-suppressed T1-weighted image showing heterogeneous enhancement of the mass with linear-shaped lesions showing low signal intensity. Vascular structures were noted in the peripheral aspect of the tumor. F. Histology of the tumor shows fascicles of spindle cells with dense fibrous tissue and trapped adipose tissue on hematoxylin-eosin staining (original magnification, × 100). G, H. The spindle cells show immunoreactivity for (G) cluster of differentiation 34 and (H) desmin (original magnification, × 100).

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