Sarcomatoid carcinoma of the colon: A rare cause of bowel obstruction

Colorectal Sarcomatoid Carcinoma: 30-Year Experience

Background: Primary colorectal sarcomatoid carcinoma is a rare and aggressive malignant neoplasm that displays mixed epithelial and mesenchymal differentiation, with uncertain histogenesis. First described in 1986, there is a paucity of literature related to this condition and there are no evidence-based treatment guidelines. The aim of our study is to present our 30-year experience with primary colorectal sarcomatoid carcinoma. Methods: Retrospective single-center analysis of all patients treated for primary colorectal sarcomatoid carcinoma from 1992 to 2022. The primary outcome was response to treatment strategy and overall survival. Results: A total of six cases met eligibility criteria. Three were male (50%) with a mean age at diagnosis of 59 years (range, 49-72). Four neoplasms were located in the rectum (66%) and two in the colon. Mean tumor size at diagnosis was 4.8 cm (range, 2.8-7.0). Three patients were treated endoscopically and three underwent oncologic surgical resection. Five experienced recurrence and one expired from other comorbidities. The mean survival among those with colonic and rectal sarcomatoid carcinoma was 7 months (range, 3-11) and 39 months (range, 9-60), respectively. Discussion: Primary colorectal sarcomatoid carcinoma is a rare malignant tumor with poor prognosis. Treatment modalities have not been standardized and despite multimodal therapy, disease recurrence and/or metastasis is likely to occur. Further studies are necessary to determine optimal treatment to improve outcomes.

Colorectal Carcinoma With Sarcomatoid Components: Report of 15 Cases and Literature Review of an Exceedingly Rare Carcinoma Subtype

Colorectal carcinoma with sarcomatoid components (which includes so-called carcinosarcomas and sarcomatoid carcinomas) is a rare subtype with 50 reported cases in the literature and overlapping criteria with undifferentiated carcinoma. We collected and described 15 cases from 10 men and 5 women, with a mean age of 66 years. Symptoms included abdominal pain and gastrointestinal bleeding. Most tumors presented in the rectosigmoid region, with a mean size of 8.2 cm. The sarcomatoid component, on average, represented 58% of the tumors and took many forms, including spindled (10 cases), anaplastic (9 cases), and rhabdoid (3 cases); one case showed osteoid matrix. Tumor budding was usually high, and tumor-infiltrating lymphocytes were usually low. The sarcomatoid component was keratin-positive in 10 cases. One case showed loss of mismatch repair protein expression, and 2 cases showed SMARCA4 loss (1 also with SMARCA2 loss). Molecular testing identified mutations in KRAS (n=1), NRAS (n=2), BRAF (n=2), APC (n=1), and TP53 (n=1) in a few cases. Tumors often presented at advanced stage, with 11 cases pT4, 9 cases with nodal metastases, and 7 cases with distant metastases. Follow-up was available for 10 cases (median: 2 months), with 2 alive without disease, 3 alive with disease, and 5 dead. Our findings roughly corresponded with those in previously reported cases. Colorectal carcinoma with sarcomatoid components is rare and aggressive, with a poor prognosis for many patients. We suggest that spindled cells, anaplasia, heterologous elements, and/or a component with definable sarcomatous lineage be used to distinguish colorectal carcinoma with sarcomatoid components from undifferentiated carcinoma.