Gastrointestinal amyloidosis (GIA), a protein deposition disorder, represents a complex common pathway that encompasses multiple etiologies and presentations. It represents a significant diagnostic and treatment challenge. The disease results from the deposition of insoluble extracellular protein fragments that have been rendered resistant to digestion. GIA can be acquired or genetic, and most commonly results from chronic inflammatory disorders (AA amyloidosis), hematologic malignancy (AL amyloidosis), and end-stage renal disease (Beta-2 amyloidosis). The deposition of these abnormal proteins interferes with gastrointestinal tract (GI) organ structure and function, most notably in the liver and small bowel. Presentation from GI involvement includes cirrhotic sequelae, abdominal pain, malabsorption, and GI bleeding. Diagnosis hinges on pathologic examination of affected tissue, with classic green birefringence under polarized light. Abdominal fat pad and rectal mucosal biopsy have been described as sites of higher sensitivity for diagnosis. Serum amyloid P scintigraphy is near 90% sensitive for diagnosis of AA amyloidosis. Patients should be considered for further evaluation to rule out additional organ involvement, notably cardiac and renal. Treatment hinges on an adequate suppression of the predisposing inflammatory disorder, or malignancy, followed by supportive therapy. Prognosis varies depending on the etiology of the disease, with the AL subtype showing worse outcomes, as well as those with hepatic involvement.

Neuroendocrine tumors (NET) previously called carcinoid tumors are neoplasms of enterochromaffin/neuroendocrine cell origin which display neurosecretory capacity that may result in the carcinoid syndrome. The annual incidence of patients with NET is 8.4 per 100000; yet many NET remain asymptomatic and clinically undetected. A majority of NET follows a benign course; however, some will display malignant characteristics. NET most commonly occur in the gastrointestinal tract (67%) and bronchopulmonary system (25%). Gastrointestinal NET occur within the stomach, small intestine, liver, and rectum. We report a retrospective study of 11 subjects: Eight with benign carcinoid tumors: duodenal bulb (n = 2), terminal ileum (n = 1), sigmoid colon (n = 2), and rectum (n = 3); three with malignant carcinoid: liver (n = 1) and intra-abdominal site (n = 2). The diagnosis, endoscopic images, outcome, treatment and review of the literature are presented.

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Colon cancer is the second most common type of cancer in females and the third in males, worldwide. The most common sites of colon cancer metastasis are the regional lymph nodes, liver, lung, bone and brain. In this study, an extremely rare case of colon adenocarcinoma with extensive metastasis to the mediastinal lymph nodes without any other organ involvement is presented. A 44-year-old Caucasian male presented with abdominal pain, a change in bowel habits, melena and weight loss. Colonoscopy revealed a large friable, ulcerated, circumferential mass in the ascending colon. Biopsies were consistent with the diagnosis of invasive moderately differentiated adenocarcinoma. Subsequently, right colon resection was performed, and pathological analysis revealed moderately differentiated adenocarcinoma of the right colon with extensive regional lymph node involvement. Computed tomography (CT) scans of the chest, abdomen and pelvis were performed preoperatively as part of routine staging for colon cancer. No liver or lung pathology was identified; however, multiple pathologically enlarged mediastinal lymph nodes were observed. Endoscopic ultrasound with fine needle aspiration of the largest mediastinal lymph node, which measured 5.2×3.5 cm on CT scans, was performed. The pathology was again consistent with the diagnosis of metastatic colorectal primary adenocarcinoma. At present, no optimum treatment has been identified for metastatic colon cancer to the mediastinal lymph nodes. The patient in the current case received chemotherapy with folinic acid, fluorouracil and oxaliplatin (FOLFOX), as well as with bevacizumab. Initial follow-up CT scans of the chest revealed a positive response to treatment. Physicians, in particular, radiologists, must consider the mediastinum during the first evaluation and further follow-up of patients with colorectal carcinoma even in the absence of metastasis.