A descriptive histopathological framework for radiotherapy-related muscle injury in salvage surgery for hypopharyngeal cancer

Radiotherapy-related normal tissue injury is clinically important in salvage surgery for hypopharyngeal cancer, but its histopathological features in clinical specimens remain poorly defined.

To propose a practical descriptive histopathological framework for radiotherapy-related muscle injury using salvage surgical specimens.

We retrospectively examined anterior cervical muscle specimens obtained during salvage total pharyngolaryngectomy after definitive radiotherapy or chemoradiotherapy. Two head and neck surgeons with postgraduate training in pathology independently reviewed H&E-stained sections without reference to treatment exposure and, after discussion, established a four-tier semiquantitative framework based on recurring morphologic patterns. A board-certified head and neck pathologist subsequently reviewed all specimens blinded to treatment exposure and clinical information. No statistical comparison between treatment groups was intended.

Thirteen previously irradiated patients and two non-irradiated controls were included. Irradiated muscles showed a spectrum of changes ranging from mild myofiber swelling and atrophy to rupture, fibrosis, necrosis, and scarring. Non-irradiated controls showed preserved muscle architecture.

This study proposes a practical descriptive framework for radiotherapy-related muscle injury in salvage surgery. The grades should be interpreted as predominant morphologic patterns rather than rigid chronological stages or statistically validated treatment-specific categories.