Ultrasound and Magnetic Resonance Imaging Features of Calcifying Aponeurotic Fibromas

Abstract

ObjectivesTo report characteristic imaging findings of calcifying aponeurotic fibromas (CAFs) on ultrasound (US) and magnetic resonance imaging (MRI).MethodsEight patients with CAF based on our institutional pathology database from 2000 to 2019 were consecutively included. Images were assessed as follows: with plain radiographs for the presence of soft tissue calcifications; with US for the presence of microlithiasis (a nonshadowing hyperechoic focus <3 mm) and discrete calcifications, size, location, margin, echogenicity, and relationship with surrounding structures; and with MRI for the presence of MRI microlithiasis (scattered tiny signal‐void dots), margin, signal intensity, contrast enhancement pattern, and relationship with surrounding structures.ResultsCalcifying aponeurotic fibromas occurred most commonly in the foot (n = 5), followed by the hand, ankle, and knee, respectively. Half of the lesions (n = 4) showed intralesional calcifications on plain radiographs. On US, all lesions showed microlithiasis. They involved the subcutaneous (n = 5), perifascial (n = 2), and intermuscular (n = 1) layers. Margins were circumscribed (n = 3) or irregular (n = 5), whereas the echogenicity of the underlying tumor matrix was hyperechoic (n = 4), isoechoic (n = 2), or hypoechoic (n = 2). All lesions were abutting (n = 7) or encasing (n = 1) an adjacent tendon. On MRI, all CAFs showed tiny signal‐void dots and irregular margins. Signal intensity was mostly hyperintense (n = 5) on T2‐weighted images and all hypointense on T1‐weighted images. Three lesions showed heterogeneous contrast enhancement, and 3 showed uneven marginal enhancement.ConclusionsA CAF should be considered a differential diagnosis if a soft tissue mass abutting or encasing the tendon or fascia shows US or MRI microlithiasis.

Imaging of Pediatric Soft Tissue Tumors and Tumor-like Conditions

“…Kang et al published a small series of eight patients with calcifying aponeurotic fibromas describing their sonographic and MRI features. 37 In this series, half of the cases were hyperechoic, two isoechoic, and two hypoechoic, and all lesions showed microlithiasis. Radiographs show a nonspecific soft tissue shadow with fine stippled calcifications.…”

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

“…CT is useful to determine calcified areas in the lesion and its association with the adjacent bone [6] . CT usually reveals a nonspecific soft tissue mass with stippling of calcification, in addition to showing the infiltrative growth pattern of the lesion in the surrounding tissues [ 4 , [13] , [14] , [15] , [16] , 19 ]. On MRI, CAF often appears as a poorly defined subcutaneous mass with intermediate to low signal intensity on T1-weighted sequences [6] .…”

Calcifying aponeurotic fibroma at the sole of the foot in a 5 year old girl. A case report with 5 years follow up

“…On x-ray, CAF is presented as a protrusion on soft tissue with peculiar calcific stippling in some cases, however it is not always correlated with pathological calcification [2]. Ultrasound is useful for visualizing the extension of the lesion [9] and can detect microlithiasis regardless of the presence of visible calcifications on plain radiographs [15]. Computed tomography reveals non-specific soft tissue mass with stippling of calcification.…”

“…MRI can orient the extent of the lesion, possible bone involvement and preoperative planning [2]. Ultrasound can be utilised to initially rule out a fluid-filed mass, such as a ganglion cyst [12].…”