1629 A Rare Case of Large Cell Neuroendocrine Carcinoma of the Colon

Abstract

INTRODUCTION: Colorectal cancers are some of the most common cancers worldwide. Histologically, the vast majority of these cancers are adenocarcinomas. Neuroendocrine tumors of the colon are much less common, and large cell neuroendocrine carcinomas (LCNEC) are even rarer, accounting for less than 1% of all colorectal cancers. Furthermore, LCNEC is a very aggressive tumor with a tendency towards early metastasis. We present a case of LCNEC in a female who initially presented with symptomatic anemia. CASE DESCRIPTION/METHODS: A 69-year-old female with a PMH of HTN presented to the hospital complaining of fatigue for 2 weeks. The patient also admitted to abdominal pain and weight loss for 5 months, but denied any frank blood loss. The patient’s family history was significant for colon cancer in her mother and grandson. Despite this, the patient had never had a colonoscopy. Initial labs showed a Hgb of 6. After the patient was resuscitated, endoscopy was performed. EGD showed antral gastritis, while colonoscopy showed a large ulcerated and oozing cecal mass. A staging CT showed hepatic metastasis. The patient’s preliminary pathology report stated the cecal mass was an invasive, poorly differentiated adenocarcinoma. Surgery was consulted, but due to metastasis, they recommended palliative chemotherapy. Oncology was consulted and planned for FOLFOX chemotherapy. The patient’s final pathology report differed from the initial diagnosis, stating the colon mass was a LCNEC, which was supported by the fact that the tumor cells were immunoreactive for chromogranin, synaptophysin and CD56 and immunonegative for CDX-2 and CK20. On outpatient follow-up 2 weeks later, patient was noted to be dehydrated with worsening appetite and pain, so she was admitted. The patient’s condition continued to deteriorate however, and after a thorough discussion, the patient elected for home hospice. DISCUSSION: With improved screening helping to detect colonic lesions earlier, death rates from most colorectal cancers have been dropping. However, a diagnosis of LCNEC portends a poor prognosis as these tumors are very aggressive with a median overall survival of 10 months. Surgery is often the primary means of treatment, however that poses a problem with LCNECs, as most have already metastasized by the time of diagnosis. In our patient, her metastatic disease precluded surgery and her rapid decline made chemotherapy less tenable. This case helps highlight the importance of screening awareness, especially in patients with a family history.