Coexisting primary central nervous system non-Hodgkin’s lymphoma and colorectal adenocarcinoma: A case report

A 61-year-old female presented with night sweats following a resection for non-Hodgkin’s lymphoma of splenium corporis callosi. A positron emission tomography-computed tomography scan demonstrated that original lymphoma activity remained. A new ascending colon mass was identified simultaneously, which was diagnosed as an adenocarcinoma following the surgery. To the best of our knowledge, this is the first case to report a coexistence of primary central nervous system non-Hodgkin’s lymphoma and colorectal adenocarcinoma. The case poses a difficult clinical challenge.


Introduction
Primary central nervous system non-Hodgkin's lymphoma (PCNSNHL) is rare and accounts for 0.8-1.89% of intracranial tumors (1). The occurrence of PCNSNHL confounded by another malignancy is extremely uncommon. The pathogenesis of such a condition is not well established. The present study describes a case of coexisting PCNSNHL and colorectal adenocarcinoma for the first time. Written informed consent was obtained from the patient's family.

Discussion
Synchronous carcinomas are defined as multiple separate neoplasms that are diagnosed at the same time or within a six-month period of identifying the primary lesion. The gross and histological criteria of synchronous carcinomas, described by Warren and Gates in 1932 (2), are as follows:

Coexisting primary central nervous system non-Hodgkin's lymphoma and colorectal adenocarcinoma: A case report
i) the neoplasms must be clearly malignant as determined by histological evaluation; ii) each neoplasm must be geographically separate and distinct; and iii) the possibility that the second neoplasm represents a metastasis should be excluded. Colorectal neoplasm confounded by lymphoma is in line with the criteria. The condition is uncommon. As far as we are   aware, all the relevant studies are individual case reports (3)(4)(5)(6)(7)(8)(9) where the two carcinomas are localized in the same site, including the intestine or intestinal lymph nodes. Colorectal neoplasm confounded by extraintestinal lymphoma is rarer. Chang et al (10) reported an Epstein-Barr virus-positive case that was diagnosed as diffuse large B cell lymphoma in the cranial cavity and the ileocecal junction area. Following treatment with rituximab and chemotherapy, the cranial carcinoma disappeared, but the ileocecal lesion remained. Microscopic examination of the ileocecal lesion that was removed surgically demonstrated that it was an adenocarcinoma confounded by residual lymphoma.
All the previously mentioned studies had a colorectal neoplasm and lymphoma in the same site. By contrast, the present study described the case of an elderly female with coexisting PCNSNHL and colorectal adenocarcinoma for the first time, with lymphoma in the cranial cavity and adenocarcinoma in the intestinal cavity. No hepatic or pulmonary metastases were observed in the first PET-CT scan (Fig. 3A, B, E and F), and the biopsy revealed a high-grade intraepithelial neoplasia. After four cycles of chemotherapy, hepatic and pulmonary metastases were discovered in the second PET-CT scan (Fig. 3C, D, G and H). The second biopsy revealed adenocarcinoma. Similar changes were observed in the study by Chang et al (10). PCNSNHL may lead to systemic immune function changes, resulting in intestinal tumorigenesis, which was accelerated by chemotherapy. Although the metastases may simply be due to chance, it is recommended that patients with PCNSNHL periodically undergo tumor marker examinations, a whole-body CT scan and electronic colonoscopy during chemotherapy.
The development of a malignancy, including colorectal neoplasm and lymphoma involves oncogenes and associated genes. The genes that are associated with colorectal neoplasm and lymphoma have been identified to include C-myc, Bcl-2 and survivin (11)(12)(13)(14)(15)(16)(17). C-myc is an oncogene that plays a central role in the genesis of numerous human cancers. Bcl-2 and survivin belong to the inhibitor of apoptosis family of proteins. These genes are likely to take part in the development of a synchronous occurrence of PCNSNHL and colorectal adenocarcinoma.
In addition, common drugs in the chemotherapy regimen for PCNSNHL are cyclophosphamide, doxorubicin, vincristine and prednisone, while those in the chemotherapy regimen for colorectal neoplasm are 5-fluorouracil, capecitabine and antitumor platinum complexes. The two groups of drugs rarely overlap with each other. Therefore, further research is required to identify how to optimize the chemotherapy regimen in patients with coexisting PCNSNHL and colorectal adenocarcinoma. C-myc, Bcl-2 and survivin may offer breakthrough treatments for this disease in the future.