Lymphoepithelioma-like carcinoma: a rare case of rectal cancer.

Lymphoepithelioma-like carcinoma (LELC) is a histological variant that resembles nasopharyngeal lymphoepithelioma and occurs in various locations such as the salivary glands and lung. LELCs in the digestive tract are rare, accounting for only 2% of cases, being exceptional in the rectum. We present the case of an 84-year-old man with rectorrhagia, whitish malodorous discharge and constipation of one month's duration. Rectal examination identified a tumour. Colonoscopy revealed a rectal lesion that was confirmed by biopsy as malignant, and MRI showed an extensive rectal tumour. Histopathology revealed undifferentiated carcinoma with acute inflammatory infiltrate, consistent with LELC. Immunohistochemistry was positive for keratins 5/6, 18, 20, CEA and BER.EP4, while in situ hybridisation for Epstein-Barr virus (EBV) RNA was negative. The multidisciplinary decision included neoadjuvant radiotherapy and anterior rectal resection. The patient remains in complete response two years after treatment. Histologically, LELC is characterised by an acute inflammatory infiltrate interspersed with poorly differentiated neoplastic cells. The stomach is the most commonly affected region in the gastrointestinal tract, with more than 80% of gastric LELCs associated with EBV. To date, only four cases of rectal LELC have been reported, and its association with EBV was demonstrated in only one case. There are no standard treatments for rectal LELC, underscoring the need to gather more cases to understand its pathogenesis and develop effective treatment strategies.