Primary colonic signet-ring cell carcinoma in an elderly patient: a rare case report

Signet-ring cell carcinoma (SRCC) is a rare and aggressive subtype of colorectal cancer (CRC), accounting for less than 1% of cases. It is characterized by mucin-laden cells with eccentrically displaced nuclei, giving a signet ring appearance. Compared to adenocarcinoma (AC), colonic SRCC tends to occur at a younger age, presents at a more advanced stage, and carries a significantly poorer prognosis.

We report the case of a 71-year-old male who presented with a 4-month history of crampy abdominal pain, significant weight loss, nausea, and fatigue. Imaging revealed a circumferential ascending colonic mass with pericolic fat invasion. Colonoscopy and biopsy confirmed SRCC. The patient underwent a right hemicolectomy, which revealed a pT4a, N2b tumor with invasion into the visceral peritoneum, metastatic involvement of 11 out of 14 lymph nodes, tumor budding, and mesenteric tumor deposits. Surgical margins were negative. The postoperative course was uneventful, and the patient was discharged in stable condition on the fifth postoperative day. The patient subsequently completed adjuvant chemotherapy and remains under close follow-up.

Colonic SRCC is an uncommon but highly aggressive CRC variant associated with late presentation, rapid progression, and poor outcomes. It differs from AC by its predilection for advanced stage at diagnosis, higher nodal involvement, and dissemination. Histopathology remains the gold standard for diagnosis, while computed tomography and magnetic resonance imaging aid in staging. Surgery with adjuvant chemotherapy provides the best opportunity for disease control, though recurrence is frequent. Multidisciplinary care, molecular profiling, and vigilant surveillance are critical to improving survival.

Colonic SRCC is a rare and aggressive subtype of colorectal cancer, characterized by poor survival and frequent metastasis. Although uncommon in older adults, it should be considered in the differential diagnosis of patients presenting with unexplained gastrointestinal symptoms, regardless of age.