Heterotopic ossification of the masseter muscle following injection lipolysis: A case report and review

Injection lipolysis represents a commonly used modality for non-surgical facial contouring and is generally considered safe. We report a rare and severe complication following jawline injection lipolysis in a 35-year-old woman who developed progressively severe trismus and pain. Imaging revealed a solid mass within the right masseter muscle, which required subsequent surgical excision. Histopathology demonstrated heterotopic ossification of the affected masseter muscle. Postoperatively, mouth opening markedly improved. This case highlights an uncommon but serious adverse event of injection lipolysis, emphasizing the importance of precise injection technique, detailed anatomical knowledge, and awareness of potential off-target effects in facial applications.