Undifferentiated colon carcinoma (UCC) is described as no differentiation on microscopic investigation of colonic specimen. A UCC is classified as 4th grade according to the International Union Against Cancer (UICC) tumor classification, and as high grade by the American Joint Committee on Cancer (AJCC), seventh edition. The differentiation level of the pathologic specimen is the crucial prognostic factor; compared with a well-differentiated tumor, a poorly differentiated tumor has an unfavorable prognosis. Undifferentiated gastrointestinal carcinomas are rarely seen. At the time of diagnosis, patients with UCC generally present with lymph node and/or hematogenous metastasis with advanced stage tumor(s). This feature negatively affects the prognosis. Among all patients with UCC, the 5-year survival rate is 34%.
Our patient with UCC was a 38-year old male who came to the Department of Gastroenterology because of abdominal pain, weight loss, and anemia. Colonoscopy revealed an ulcerovegetan mass in the ascending colon. The histopathologic finding was a grade 2 adenocarcinoma. The patient's preoperative laboratory findings included: carcinoembryonic antigen (CEA), alpha-fetoprotein (AFP), CA19-9 and complete blood count were within normal limits. Abdominal computed tomography showed a 10 cm mass in the ascending colon at the level of the hepatic flexure. There were no metastatic findings. At operation, an extended right hemicolectomy and excision of a mass from the anterior abdominal wall were carried out.
Histopathologic evaluation of the mass indicated a UCC with perineural invasion without vascular invasion, a pT4-tumor. No cancer was seen at the distal surgical border of the specimen. No metastatic involvement was found in 65 pericolic and periintestinal lymph nodes. Analysis demonstrated pancytoceratin, cytoceratin 20 and CEA expression. At the end of the evaluation tumor was classified as Stage IIB (T4a N0 M0). The patient was referred to the Department of Oncology.
After an 8-month disease-free period, the patient presented to the Department of Surgery because of a mass in his left palm (Figure 1). The mass in his palm was painless, fixed and solid. The patient was referred to the Division of Plastic Surgery where he underwent surgery on his left hand. Pathologic evaluation revealed a poorly differentiated adenocarcinoma (Figure 2).
In conclusion, while most colorectal cancers seen are adenocarcinoma, the rare possibility exists of encountering an undifferentiated carcinoma. At the time of diagnosis, the thought must be kept in mind that the UCC might be at an advanced stage and aggressive.