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

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.

Calcifying Aponeurotic Fibroma: A Multimodal Imaging Description of an Unusual Case Involving Soft Tissues Adjacent to the Clavicle

“…This variability in signal intensity on the T2-weighted images is likely dependent on the degree of hypocellularity or the amount of calcification or collagen within the tumor. Therefore, the calcification, the fibrous component, and the cellularity influence the characteristics of the T2-weighted signal [ 3 , 11 , 14 , 15 , 19 ]. Prominent areas of low globular signal intensity can be seen in all MRI pulse sequences, corresponding to the presence of calcification.…”

“…In 1964, Lichtenstein and Goldman termed it "fibromatosis cartilage analog." In 1973, Iwasaki and Enjoji termed the same lesion “calcifying aponeurotic fibroma” (CAF) after it was found that it was present not only in children but also in adolescents and adults [ [1] , [2] , [3] , [4] , [5] , 7 , 11 , 15 ]. Since its initial discovery, more than 150 cases have been documented in the literature [12] .…”

“…Since its initial discovery, more than 150 cases have been documented in the literature [12] . Most cases occur in the hands [10] , fingers [ 6 , 9 ], and plantar aspect of the feet [ 3 , 12 ], but they can also arise from the connective tissues of the neck, abdominal wall, back, knee [ 8 , 11 ], thigh, arm, forearm, and elbow [5] . The lesion has also been detected surrounding a joint or invading the adjacent joint, simulating gout or calcium pyrophosphate deposition disease [14] .…”