Colorectal cancer, commonly known as bowel cancer, comprises cancerous growth in the colon, rectum, and appendix, and depending on the definition criteria used can also include those found in the anus. Bowel cancer is classified according to the tumor node metastasis (TNM) staging system into stages I, II, III, and IV. Cancer that metastasizes to distal sites (stage-IV ) is usually non-curable. The regional lymph nodes, liver, and lungs are the most common sites of metastasis associated with colorectal cancer. Infrequent sites of metastasis, including the spleen, thyroid gland, spermatic cord, and skeletal muscle have also been recorded[1–4]. Although metastases from colorectal cancer to these unusual sites might occur with the status of widespread disease, nasopharyngeal metastasis from colorectal cancer had never been reported prior to this article. To our knowledge, this is the first case of nasopharyngeal metastasis from primary clorectal cancer to be reported in the literature. At present, there are four mechanisms of metastasis linked with colorectal cancer which consist of lymphatic spread, direct extension, hematogenous spread, and planting spread. Theoretically, based on the analysis of the lymphatic reflux principle and anatomical location of the nasopharynx, we speculate that hematogenous spread of the primary colorectal cancer represents the most likely mechanism of metastasis in this case.
Nasopharyngeal carcinoma often develops at the roof of the nasopharyngeal posterior wall, generally with a cauliflower-like shape which is consistent with our report. Primary cancer is common in nasopharyngeal malignancies, thus making it difficult to determine whether this lesion is metastatic or not. In this regard, attention should be paid to the patient's other symptoms, signs, and medical history which are essential for diagnosis [4]. The main clinical manifestations of nasopharyngeal carcinoma include neck mass (40%), retracted blood snot (18.7%), and ear disorders (17.0%). The rate of lymph node metastasis was 82.3% at the time of diagnosis[5]. End-stage patients may present with ocular symptoms due to the nasopharyngeal carcinoma invading the external ocular muscles and/or oculomotor nerve[6]. Likewise, nasopharyngeal metastatic carcinoma can also cause the aforementioned symptoms. Luckily, histopathological and immunohistochemical examinations enable us to identify the tumor origin of the same tissue class. In our case, the caudate homologous transcription factor 2(CDX-2) testing positive indicates that the nasopharyngeal neoplasm is a metastasis of colorectal adenocarcinoma to the nasopharynx. CDX-2 is a tumor suppressor gene, and related studies have proven that it is closely related to the development and differentiation of normal intestinal epithelial cells into cancer[7–8].
As everyone knows, the common treatment options for colorectal carcinoma consist of surgery, chemotherapy, radiotherapy, and target therapy. According to the findings of the current study, chemotherapy did not produce a favorable effect on elderly patients with nasopharyngeal malignancies. On the other hand, radiotherapy is the most commonly used and effective treatment modality for head and neck tumors. Except for some severe acute reactions of radiotherapy, both elderly and young patients are generally able to tolerate radiotherapy [9–11]. Over the past 40 years, with the advancement of technology and pharmacotherapy, more effective therapies for cancer have been developed under integrated clinical management. We conclude that these multiple relapses could be explained by a lack of adjuvant chemotherapy. Our case of atypical colorectal metastasis reminds us of the fact that the risk posed by hematogenous spread increases as the disease.progesses
In conclusion, nasopharyngeal metastases from colorectal cancer are extremely rare clinical entities. To the best of our knowledge, this is the first case reporting this occurrence, which not only enriches the database of this rare clinical entity but also reminds clinicians to be aware that metastatic carcinoma should be a top differential diagnosis when head and facial symptoms appear during the treatment of colorectal cancer. In these cases, clinical detections such as nasopharyngoscopy and brain MRI should be performed as soon as possible. These head and facial symptoms cannot be ignored, since they may indicate rapid progress and poor prognosis. Strict monitoring of patients with colorectal cancer after primary treatment would lead to the early diagnosis of such metastases and give patients more opportunities of treatment for a better prognosis.