Multiple primary tumors: Colorectal carcinoma and non-Hodgkin's lymphoma.

Introduction: Colorectal cancer (CRC) is the third most commonly diagnosed cancer, whereas lymphoma is the sixth leading cause of cancer death, 90% of which corresponds to non-Hodgkin's lymphoma (NHL). The association of these two primary tumors, a solid tumor with an hematological malignancy, is very uncommon.

Presentation Of Case: We report the case of a 47-year-old man who presented with abdominal pain, a right upper quadrant mass and 12 kg of weight loss in 9 months. The computed tomography (CT) showed a large intra-abdominal mass and a wall thickening at the rectosigmoid junction. A colonoscopic biopsy confirmed a colorectal adenocarcinoma and a laparoscopic biopsy of the intraabdominal mass confirmed a diffuse large B-cell NHL. After multidisciplinary discussion it was decided to treat first the NHL with 3 cycles of R-CHOP chemotherapy (cyclophosphamide, doxorubicin, vincristine and prednisone). The patient experienced a good response with a 70% decrease in the intraabdominal mass and a negative PET/CT. Four months after diagnosis an anterior rectal resection was performed. The patient recovered uneventfully and was discharged 5 days after surgery. The patient finally died 20 months after surgery due to disease progression.

Discussion: The association of CRC and NHL is an extremely rare scenario that represents a great multidisciplinary challenge with respect to treatment due to the scarce literature found on this topic.

Conclusion: When CRC and NHL are present, all the different disease patterns must be considered in a multidisciplinary and patient-oriented fashion, in order to decide the best therapeutic strategy for each individual.