Relationship of pain intensity to volume and tissue stiffness in patients with elastofibroma dorsi

Objective: The aim of this study was to comprehensively evaluate the relationship between pain severity and tissue stiffness measured by shear wave elastography (SWE), computed tomography (CT) density values, lesion volume, and anatomical localization features in elastofibroma dorsi (ED) lesions. Materials and Methods: This single-center study, comprising both retrospective and prospective components, included 58 patients (a total of 110 lesions) diagnosed with ED on thoracic CT. All lesions were quantitatively evaluated using SWE. Pain severity for each lesion was assessed using the Chronic Pain Grade (CPG) classification, which grades both pain intensity and disability. Lesion size, volume, CT density (Hounsfield Unit – HU) values, and localization relative to the scapula were recorded. Painful (CPG ≥ 1) and painless (CPG 0) lesions were compared, and correlation and logistic regression analyses were performed. Results: The mean age of the study population was 62,1 ± 9.4 years, and 91,4% (53/58) were female. The mean SWE value of painful lesions (3,12 ± 0,81 m/s) was significantly higher than that of painless lesions (2,59 ± 0,66 m/s) (p < 0,01). A moderate positive correlation was found between SWE values and CPG scores (ρ = 0,45; p < 0,001). Logistic regression analysis identified SWE as an independent predictor of pain presence (odds ratio [OR] = 1,8 per 1 m/s increase; p < 0,01). Lesions with inferior ectopy had a significantly higher pain rate (84,6% vs 72,2%; p < 0,05). The presence of a concomitant superior ED was also associated with a markedly higher pain incidence (91,7% vs 68,6%; p = 0,048). However, neither inferior ectopy nor a superior companion lesion resulted in a significant increase in the SWE value of the main lesion (p = 0,55 and p = 0,72, respectively). Lesion volume, dimensions, and CT density (HU) values did not differ between painful and painless groups. Conclusion: Increased tissue stiffness measured by SWE is a strong and independent determinant of pain in elastofibroma dorsi. Although anatomical factors such as inferior ectopy and concomitant superior ED significantly increase pain incidence, this effect is not attributable to increased tissue stiffness. These findings suggest that pain in such anatomical variants likely arises from mechanical compression or local nerve irritation, rather than intrinsic tissue hardness. SWE may serve as a valuable imaging tool for the objective assessment of pain in ED and contribute to clinical decision-making. Keywords: Elastofibroma dorsi; shear wave elastography; chronic pain; pain severity; scapula; inferior ectopy; Chest CT