Post-transplantation lymphoproliferative disorder (PTLD) with rectal involvement

We report the case of a 72-year-old man, with a history of kidney transplantation eight years ago, who consulted for rectal bleeding without other symptoms. The patient underwent a rectosigmoidoscopy and this examination showed a 9mm rounded ulcerated rectal lesion classified as such: Paris IIc, JNET III, KUDO V (Figure 1). The optical diagnosis suggest an adenocarcinoma with high risk of invasion. The patient then performed an ultrasound endoscopy confirming a hypoechoic lesion involving the avoid difficulties related to post-biopsy fibrosis that complicates the resection (Figure 1). The anatomopathological results do not support the diagnosis of an adenocarcinoma. What is your diagnosis?