Ultrasonographic Features of Polycaprolactone Granulomatous Reactions: Case Series and a Literature Review

Polycaprolactone (PCL) dermal fillers are widely used to stimulate collagen production and achieve long-lasting aesthetic results. Despite a favorable safety profile, case reports have described adverse events, including granuloma formation. The authors present 4 cases of granulomatous reactions after PCL injections, characterized clinically by painless, firm subcutaneous nodules and ultrasonographically by hypoechoic lesions with surface echogenic foci and comet-tail artifacts. To raise awareness among aesthetic practitioners, the authors conducted a narrative review of the existing literature on PCL-associated granulomas. They discussed the role of ultrasound in supporting the diagnosis of granulomatous reactions following PCL injections. This review highlights the diagnostic utility of ultrasonography and summarizes reported cases to date, aiming to enhance recognition and management of this potential adverse event. Level of Evidence: 4 (Therapeutic) For image description, please refer to the figure legend and surrounding text.