RECTAL ADENOCARCINOMA AND PAPILLARY THYROID CARCINOMA IN A YOUNG ADULT WITH LYNCH SYNDROME

Presentation A 44-year-old woman treated at an outpatient clinic for hereditary colorectal cancer with a diagnosis of Lynch Syndrome with a pathogenic variant in the MSH6 gene. Family history of neoplasms with sisters diagnosed with gastric and thyroid cancer at ages 36 and 35, respectively. The patient presented with colonoscopy with an ulcerative lesion occupying 50% of the circumference of the middle rectum and histopathology with well-differentiated adenocarcinoma. Magnetic resonance imaging demonstrated cT3N1M0 staging. She underwent chemoradiotherapy along the lines of the “RAPIDO trial”. Four months later, a rectosigmoidoscopy was performed which showed an ulcerated area covered with fibrin, compatible with a partial response to neoadjuvant therapy. It also brings a biopsy report of a thyroid nodule with cytology compatible with papillary carcinoma, chosen to be discussed later. The case was discussed in a clinical session, and the decision was made to perform anterior resection of the rectum and endoscopic follow-up. Proposed total hysterectomy and bilateral prophylactic adnexectomy, considering the incidence of gynecological cancer in patients with Lynch syndrome. The patient was discharged and cleared for treatment of the papillary carcinoma. Bowel continuity was restored, and the patient remains under outpatient follow-up.

Discussion Lynch syndrome is the leading cause of hereditary colorectal cancer (CRC), accounting for approximately 3% of CRC cases and 2–3% of endometrial cancer cases. With mutations in the MSH6 gene, the cumulative risk of endometrial cancer can reach 50%. The decision to perform a total hysterectomy and prophylactic salpingo-oophorectomy remains controversial; however, in this case, the option was discussed with the patient, as she had already completed her family and was undergoing surgery. Other commonly affected sites include the ovaries, stomach, brain, and prostate. Family history of malignancies must be assessed, with colorectal cancer screening starting at age 30 or 2–5 years before the youngest age of diagnosis in the family, repeated every three years. Studies have shown that colonoscopy in these patients reduces disease mortality and adds an average of 14 quality-adjusted life years compared to unscreened individuals.

Conclusion Patient education about the disease is crucial, given the high likelihood of developing neoplasms throughout life. Attention to signs and symptoms indicative of disease in the primary sites should not be overlooked.

No conflict of interest has been declared by the author(s).

Publication History

Article published online:
25 April 2025