A Collision Tumor of Adenocarcinoma and Malignant Lymphoma in the Descending Colon Showing a Notable Progression Pattern of These-different Types of Neoplasms—A Case Report—

Abstract

An 85-year-old woman was referred to the department of plastic surgery of our hospital for detailed examination with a complaint of an enlarged left submandibular lymph node in October 2019. Pathological diagnosis by excisional biopsy showed malignant lymphoma. She was found to have anemia at the time of hospitalization. On further examination, she was suspected to have concomitant descending colon cancer. In November, laparoscope-assisted left hemicolectomy and D3 lymph node dissection were performed. On pathological diagnosis of the resected specimen, the lesions formed a collision tumor of moderately differentiated tubular adenocarcinoma (invasion depth T3) and malignant lymphoma at the subserosal layer. Some of the malignant lymphoma spread surrounding the adenocarcinoma, which is a very rare pathological finding. Although metastasis of adenocarcinoma to the dissected regional lymph nodes was not observed, malignant lymphoma cells were detected in those lymph nodes. Postoperatively, chemotherapy for malignant lymphoma resulted in complete remission. However, a metastatic lesion of the central nervous system appeared in May 2020. Palliative radiation therapy was performed, and symptoms attributable to the metastatic lesion at this site were stable as of August 2020.