Purpose: To evaluate the frequency, imaging findings, and patient demographics of synchronous elastofibroma dorsi (ED) and pelvic elastofibromas.
Methods: Image archives between 2011 and 2021 were retrospectively searched for CT and MRI reports including the keyword "elastofibroma". Patients with concomitant CT and/or MRI of the chest and pelvic regions were included. The greatest thickness and side of ED were noted. Subsequently, pelvic soft tissues were evaluated for a soft tissue mass with similar radiological features to ED. When detected, its location, greatest transverse diameter, and ischiofemoral space widths were noted. Wilcoxon matched-pairs signed-rank and Mann-Whitney U-tests were performed when appropriate. Pearson's correlations were used to assess the association of presence of subgluteal-ischiofemoral elastofibromas (SGIFE) and ED thickness. The model discrimination of ED thickness was evaluated by calculating the AUC of the ROC.
Results: Eighty-eight patients (Male:Female = 8:80) with a mean age of 70.6 (±10.3) years were included. 96.6 % of patients had bilateral ED. 18.2 % of patients (all females) had at least one concomitant SGIFE. Patients with SGIFE had significantly thicker ED (p < 0.001 right; p = 0.049 left). There was a significant positive correlation between the thickness of ED and presence of SGIFE (r = 0.43, p < 0.001 right; r = 0.25, p = 0.019 left). An AUC of 0.781 (p < 0.001, 95 %-CI:0.675-0.887) and 0.659 (p = 0.049, 95 %-CI:0.523-0.794) were revealed regarding the presence of ipsilateral right and left SGIFE, respectively.
Conclusion: Concomitant SGIFE may accompany ED in up to 18.2% of cases, particularly in women with thick ED. Knowledge of this co-occurrence and the described SGIFE characteristics can facilitate correct diagnosis.
Keywords: Computed tomography; Deep gluteal space; Elastofibroma; Ischiofemoral space; Magnetic resonance imaging.
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