J Korean Soc Radiol.  2015 Aug;73(2):131-135. 10.3348/jksr.2015.73.2.131.

Radiological Features of a Fibro-Osseous Pseudotumor in the Digit: A Case Report

• Kwak MJ
• Kim SK
• Lee SU
• Jun SY
• Lee AH

• KMID: 1964266
• DOI: http://doi.org/10.3348/jksr.2015.73.2.131

Abstract

A fibro-osseous pseudotumor is a rare ossifying soft tissue lesion, which is thought to be a reactive rather than a neoplastic lesion, developing due to repeated trauma. The lesion mostly occurs in the subcutaneous tissue of the proximal phalanx of the digit and predominantly affects young adults, with a slight predominance in females. The clinicopathological features can mimic those of malignant soft tissue lesions, and diagnosis can be difficult. Less is known about the radiological appearance of the lesion, including magnetic resonance imaging (MRI) features, than about histological signs. Here, we report radiological findings, including MRI features, of a fibro-osseous pseudotumor of the digit in a young female.

MeSH Terms

Diagnosis
Female
Humans
Magnetic Resonance Imaging
Myositis Ossificans
Subcutaneous Tissue
Young Adult

Figure

• 

  Fig. 1 A plain radiograph demonstrating a fairly circumscribed, ossified soft tissue mass, adjacent to, but separate from, bone, overlying the proximal phalanx of the right middle finger, without any periosteal reaction or cortical change.

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  Fig. 2 Hand MRI of a 19-year-old female presenting palpable mass on the digit. A. An axial T1-weighted spin-echo image (TR/TE, 912/13) showing a soft tissue mass (arrows) overlying the proximal phalanx of the right middle finger, without any periosteal or cortical reaction. The peripheral component of the mass is of intermediate signal intensity, and an internal region is hyperintense, likely indicating osseous differentiation surrounded by fibroblastic proliferation. B. A coronal T2-weighted spin-echo image (TR/TE, 4360/80) showing an ovoid-shaped hyperintense mass (arrows), with several foci of intermediate signal intensities, overlying the proximal phalanx of the right middle finger, suggesting mixed osseous and fibroblastic proliferation. C. On the axial fat-suppressed contrast-enhanced T1-weighted image (TR/TE, 650/12), the peripheral component of intermediate signal intensity on the axial T1-weighted spin-echo image demonstrates contrast enhancement (arrows), suggesting a fibroblastic proliferative area, whereas the central area (exhibiting little contrast enhancement) is thought to be the osseous portion. TE = echo time, TR = repetition time

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  Fig. 3 Photomicrographs of the fibro-osseous pseudotumor. A. The tumor features a peripheral fasciitis-like stroma of fibroblasts and a central irregular immature osteoid (H&E, × 40). B. There is mild to moderate cellular proliferation of fibroblasts at the periphery, and immature osteoid formation with osteoblastic rimming (H&E, × 100). H&E = hematoxylin and eosin

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