Deep fibromatoses are soft tissue tumors of peculiar histopathological composition which in turns is reflected on their imaging features. The included patients’ ages ranged from 2 to 75 years; 5 patients (12.5%) who had extra-abdominal fibromatoses were younger than 10 years. Literature stated that common presentation is between puberty and the age of 40 years with less than 5% of pediatric age affection [8, 9] A female predominance is noted in our study; the 3 abdominal wall lesions were exclusively females at child bearing age [2, 10]
Multi-centric extra-abdominal fibromatosis was encountered in 7 (21.8%) patients, which is a slightly higher incidence compared with the reported literature being 5–15% [2, 11, 12] The majority of the lesions were extra-abdominal type, mostly proximal in location, at the pelvic girdle and thighs and at the shoulder girdle and upper arm. They predominantly demonstrated ill or partially defined margins, which is also reported in other studies [13, 14] In their study, Quinn et al. concluded that even well-demarcated margins, which was found in half of their studied lesions, are misleading as, microscopically, all of the lesions invaded adjacent structures 
On T1-weighted images, the majority of lesions exhibited low and/or intermediate signal intensity, while on T2-weighted images, lesions were mainly of intermediate or mixed intermediate and low signal intensity. Most of the examined lesions showed heterogeneous moderate to marked contrast uptake. This was comparable with signal properties stated in literature [1, 9, 13, 15] Two lesions in our study exhibited predominantly low signal across all of the examined sequences with no evidence of enhancement; this can be attributed to the predominance of collagen and low cellularity.
Areas of persistent low signal intensity across different sequences, pre- and post-contrast images, were seen in 95% of lesions, varying in shapes (bands, conglomerate bulks) and sizes. Such MR finding has always been described in literature as a valuable diagnostic feature representing acellular collagen [1, 2, 15] It was not demonstrated in 2 extra-abdominal lesions in our study, reflecting predominance of cellularity and aggressive nature in these lesions. It is worth to mention that these 2 lesions also exhibited restricted diffusion pattern (purely high signal on DWI and intermediate signal on ADC map) as well as moderate and marked enhancement, confirming their aggressive nature along other MR features. Other valuable implementation of such low signal intensity areas is monitoring therapeutic response. A positive response is reached by progressive tumor collagenization; a feature reflected by decreased T2 signal and enhancement among the lesion regardless of it size changes [1, 2]
Fascial tail sign was demonstrated in 82.5% of the studied lesions, exclusively extra-abdominal lesions. This is a comparable percentage with that stated in literature [1, 10] It was best traced in the post-contrast images. The literature highlighted its importance, not just as distinguishing feature of deep fibromatosis but more importantly as a guide for excision with free surgical margins [16, 17]
Qualitative analysis of the DWIs and the ADC map showed the predominance (92.5% of lesions) of high signal intensity on the DWIs, whether purely or mixed with low signal areas. On the corresponding ADC map, this was reflected as intermediate or mixed intermediate and low signal intensity, reflecting diffusion restriction. The areas of persistently low signal intensity on both the DWIs and the ADC map corresponded to the previously described low signal bands and areas. Literature described such pattern as indicative of fibromuscular tissue and mature fibrous tissue  Other studies described low signal on DWI and ADC as “T2-blackout effect” attributed by factors which produce T2 shortening  These low signal areas showed very low mean and minimum ADC values. This can be explained by the fact that fibrous tissue works as an obstacle to water molecules diffusibility. While placing the ROIs, we considered encompassing the largest tumor area possible without including these low signal areas.
In our study, the lesions showed average mean and minimum ADC values of 1.41 ± 0.26 × 10− 3 mm2/s and 0.79 ± 0.43 × 10− 3 mm2/s respectively. The measured mean ADC values for deep fibromatosis lesions in other studies ranged from 1.2 to 1.9 × 10− 3 mm2/s [5, 20, 21] The average mean ADC value in our study is closer to that measured by Oka et al. and Pekcevik Y et al. The average minimum ADC value is far less than minimum ADC value mentioned by Oka et al.; in their series, however, the authors mentioned as a part of their study limitations that they did not examine the agreement of minimum ADC with corresponding lesions’ cellularity beside that they included only 8 fibromatoses lesions.
We comparatively reviewed the pre-contrast T1 and T2 WIs with the post-contrast images. The post-contrast images are of superior value in accurately assessing the local disease extent. Post-contrast images identified 2 synchronous lesions and accurately delineated extra-compartmental extension in other 4 lesions. Synchronous lesions, intra-compartmental, and extra-compartmental extensions were missed due to intermediate signal on T1 and T2WIs, rendering them indistinguishable from adjacent or invaded muscles. All missed lesions were readily detected on post-contrast images by virtue of their eminent enhancement, thereby influencing the management plan. They also showed a corresponding diffusion restriction pattern, denoting aggressive nature. The latter has a potential implication in patients suffering renal impairment. In these patients, adding a diffusion sequence to MR study will provide necessary information for management plan meanwhile avoiding harmful effects of contrast administration.
There were some limitations in our study. First, we could not correlate the radiologic findings to microscopic histopathologic appearance as all the included lesions were pathologically proven using needle biopsy. The lack of standardized protocols for placement of ROI to measure ADC value is also a limitation here; however, we unified the methods used in all the included lesions.