A rare case report of mucinous adenocarcinoma exacerbated by long-standing solitary rectal ulcer syndrome.

Background: Solitary rectal ulcer syndrome (SRUS) is a rare chronic rectal lesion with potential for malignant transformation, although cases of rapid progression to mucinous adenocarcinoma are infrequent. This case report highlights such an instance in a 29-year-old male patient, emphasizing the importance of vigilance among clinicians for detecting canceration in SRUS patients. Case Description: The patient presented with recurrent constipation and anal discomfort, initially diagnosed with SRUS based on colonoscopy and pathological examination. Despite long-term mesalazine treatment, symptoms persisted, and subsequent evaluation revealed the development of mucinous adenocarcinoma within a short period. Surgical resection, combined with adjuvant FOLFOX chemotherapy, effectively controlled cancer progression. Immunohistochemical analysis showed positive expression of MLH1(+), MSH2(+), MSH6(+), PMS2(+), and HER2(+), providing molecular insights into SRUS-associated mucinous adenocarcinoma. Conclusions: This case underscores the need for increased awareness among clinicians regarding the potential for cancerous transformation in SRUS patients. Early detection and intervention are crucial for improving outcomes in SRUS-associated malignancies. Furthermore, this case adds to existing literature by presenting a rare instance of SRUS progressing rapidly to mucinous adenocarcinoma, highlighting the significance of regular monitoring and timely intervention in such cases. Further research is warranted to elucidate underlying mechanisms and risk factors, guiding future clinical practice and treatment strategies.