A 64-year-old man admitted to our hospital reported watery diarrhea for the last 13 months. He had up to 8 bowel movements per day, worsening in the month prior to admission, resulting in 15 to 20 movements per day without response to antidiarrheals. He did not report steatorrhea or blood, mucus, or pus in the stool. He did not suffer from asthenia, anorexia, fever, or vomiting. He did, however, report a 20-kg weight loss during the past year. Arthralgia, dyspnea, or abdominal pain were not present. A right jugular paraganglioma was diagnosed more than 30 years ago, and its extension affected several vital structures (Figure 1). He was not on any medication and had no other medical conditions.
Physical examination revealed normal vital signs, with pale skin and mucus. The right side of the face was deformed by a prominent, tight, hypervascular cervical tumor, with peripheral facial palsy. Abdominal examination showed normal bowel sounds without tenderness, distension, or masses. Laboratory studies showed anemia (9.4 g/dL), thrombocytosis (724,000 platelets/microL), elevated erythrocyte sedimentation rate (120 mm), and hypoalbuminemia (2.7 g/dL). Alkaline phosphatase and gamma glutamyltransferase were slightly altered at 141 U/L and 100 U/L, respectively. 24-Hour urine collection showed 1.2 g/d proteinuria, with normal creatinine (1.16 mg/dL). Chest x-ray was normal.
Stool specimen culture (including parasite analysis) was negative, and celiac disease antibody tests (anti-tissue transglutaminase antibody) and an intestinal biopsy were unrevealing. Thyroid hormone tests, vasoactive intestinal polypeptide (VIP), and 5-hydroxyindoleacetic acid (5-HIAA) urine tests also returned normal results. Serum electrophoresis and 24-hour urine immunofixation electrophoresis did not show a monoclonal spike. Immunoglobulin G and M levels were normal; however, immunoglobulin A levels were almost twice the upper limit (843 mg/dL). Tests for hepatitis B antigens and anti-hepatitis C antibodies were negative.
Rheumatoid factor, anti-nuclear antibody, anti-smooth muscle antibody, anti-mitochondrial antibody, and QuantiFERON  TB tests were also negative. A computed tomography (CT) scan showed mucosal enhancement and local hyperemia in the descending and sigmoid colon without abdominal masses or thickenings. Corresponding with the CT findings, a colonoscopy revealed an unspecific inflamed and friable mucosa. A histologic assessment of the affected colon biopsies showed extracellular eosinophilic deposits in the submucosa and vessel walls, with apple green birefringence with Congo red stain, indicative of amyloidosis (Figure 2). An immunohistochemical stain was positive to AA-type amyloid (Figure 3).