Investig Magn Reson Imaging.  2017 Dec;21(4):259-263. 10.13104/imri.2017.21.4.259.

Calcifying Aponeurotic Fibroma of the Knee: a Case Report with Radiographic and MRI Finding

• Lee SH
• Lee IS
• Song YS
• Choi KU
• Kim JI
• Song JW

• KMID: 2400380
• DOI: http://doi.org/10.13104/imri.2017.21.4.259

Abstract

Calcifying aponeurotic fibroma (CAF) is an uncommon benign tumor and a locally aggressive fibroblastic lesion. It commonly affects the palmar side of the hand and fingers, and the soles of the feet. The typical clinical manifestations are known as a poorly circumscribed, slow-growing, and asymptomatic firm mass. Most CAFs usually reveal low to intermediate or isointensity on T1-weighted images, and strong heterogeneous enhancement. However, various signal intensities on T2-weighted images have been reported depending on the degree of hypocellularity or the amount of calcification or collagen within the tumor. This report provides the radiographic and MRI finding of CAF arising in uncommon site, the knee region, of a 19-year-old male who presented with a painful and palpable mass.

Keyword

Calcifying aponeurotic fibroma; Knee; Magnetic resonance imaging

MeSH Terms

Collagen
Fibroblasts
Fibroma*
Fingers
Foot
Hand
Humans
Knee*
Magnetic Resonance Imaging*
Male
Young Adult
Collagen

Figure

• 

  Fig. 1 A 19-year-old male patient with left knee pain. Tubular or nodular sclerotic lesions were seen in the medial femoral condyle on the anteroposterior view of the left knee radiograph. A slightly increased opacity appeared in the soft tissue area of the medial femoral condyle.

• 

  Fig. 2 (a) A soft tissue tumor about 3 cm in size was seen adjacent to the cortex of the medial femoral condyle on the axial T1-weighted MR image. The mass displayed isointensity to slightly high signal intensity compared to adjacent muscles and caused slight cortical erosion. The outer border of the tumor had a well-defined margin, but was not clearly separated from the medial patellofemoral ligament. Sclerotic lesions within the bone marrow exhibited dark signal intensities. (b) The mass displayed heterogeneously high signal intensity on the axial fat-suppressed T2-weighted image. The intermediate-to-low signal intensity portion was seen in the tumor. The posterior portion of the mass was adherent to the femoral origin of the medial collateral ligament. (c) The mass exhibited heterogeneously diffuse enhancement on the axial contrast-enhanced T1-weighted MR image. A low signal intensity region that did not enhance was observed in the mass.

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  Fig. 3 (a) Gross specimen of the resected tumor showed pinkish-red color and was measured at about 2.8 cm. (b) Pathologic specimen (× 100; Hematoxylin & Eosin [HE] staining) demonstrated that calcification is surrounded by fibroblastic cells, radiating from the center. (c) Cartilaginous differentiation and hyalinization in calcified areas are well seen on another slide (× 100; H&E staining).

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