P77 | A rare late side effect of radiotherapy

Premises: The number of patients undergoing radiotherapy (RT) for malignancies is increasing. While RT is an effective treatment, it is not without side effects.Description of the Case report: A 77-year-old man diagnosed with remitting diffuse large cell lymphoma affecting the right lung and the C6-T3 vertebral canal with spinal compression underwent decompressive laminectomy and RT in 2015. Eight years later, he observed the development of a retrocervical mass. Suspecting a disease relapse, he underwent an MRI revealing a 10 cm encapsulated formation imprinting the superficial muscle planes without infiltration. Biopsy was inconclusive. Soon after, the mass became painful and the patient developed fever, leading to admission to our ward. Blood tests showed anemia, acute kidney injury, and signs of infection, prompting initiation of antibiotic therapy. Subsequent MRI revealed a rupture of the mass capsule with the spread of infected content into the superficial layers. The patient underwent surgical resection involving neurosurgeons, plastic surgeons, and general surgeons, resulting in a successful recovery. Histological examination showed no evidence of neoplastic disease but revealed areas of ischemic and hemorrhagic necrosis with lymphovascular ectasia and lymphomonocytic infiltrate suggestive of radiation necrosis.Conclusions: Radiation necrosis is a rare late side effect of RT that clinicians should be aware of. It is due to the damage of healthy tissues and can occur up to 9 years post-exposure in 5-15% of irradiated patients.