Case Presentation: A 64 year-old woman with no significant past medical history presented with nausea, vomiting, 50 lb. weight loss and generalized weakness for the past 6 months. Her primary care physician had prescribed treatment for possible reflux; symptoms did not improve. Three months prior, the patient was admitted to a community hospital where CT of the chest/abdomen/pelvis, upper endoscopy, brain MRI, cortisol level and thyroid function tests were all unremarkable. Her vitals were normal. She was thin with dry mucous membranes. Laboratory abnormalities included an elevated serum creatinine of 2.1 (baseline creatinine normal), potassium 3.2 mmol/L, and hemoglobin 10.3 g/dL. The patient had resolution of her weakness and AKI with intravenous fluids and electrolyte repletion, and improvement of her nausea with antiemetics. Upper endoscopy was pursued that appeared grossly normal, but random biopsies of the stomach and small bowel were taken. Pathology was stained with Congo red and revealed amyloid deposits with apple‐green birefringence under polarized light. Further workup included serum electrophoresis with immunofixation that demonstrated a M spike (< 3 g/dL) with IgG lambda. Bone marrow biopsy had amyloid deposition with AL subtype and < 10% lambda restricted plasma cells. She was diagnosed with primary systemic or immunoglobulin light-chain (AL) amyloidosis and IgG lambda monoclonal gammopathy of undetermined significance (MGUS). She was treated with systemic chemotherapy and ultimately underwent an autologous bone marrow transplant with complete resolution of symptoms.
Discussion: Amyloidoses are a group of diseases that involve the extracellular deposition of insoluble fibrils in various tissues and organs. Primary (AL) amyloidosis is the most common subtype of systemic amyloidosis. Gastrointestinal amyloidosis from AL amyloidosis is uncommon, occurring in only 1-8% of patients with systemic AL amyloidosis. Within the gastrointestinal (GI) tract, amyloid deposition occurs close to the vasculature and nerve plexuses. Motor dysfunction of the bowel may result from extensive mucosal amyloid deposition. These mechanisms are likely responsible for the non-specific symptoms seen in gastrointestinal amyloidosis, such as anorexia, nausea, diarrhea, abdominal pain, weight loss, and malabsorption. Endoscopic findings are nonspecific and can even be normal. Diagnosis of amyloidosis requires a high index of suspicion. Serum and urine electrophoresis with immunofixation should be sent to initiate the workup. A definitive diagnosis requires biopsy of the affected tissue with apple‐green birefringence and red staining with Congo red.
Conclusions: Hospitalists are frequently involved in managing patients with non-specific GI symptoms and “failure to thrive”. Patients presenting with GI manifestations often have indications for endoscopy such as weight loss, dyspepsia refractory to medical therapy, or unexplained symptoms. Suspicion of gastrointestinal amyloidosis in patients without a known history of amyloidosis is critical to making the diagnosis. Endoscopy with blind biopsies stained with Congo red should be considered for any patient with non-specific GI symptoms with unexplained weight loss, particularly if associated with a monoclonal gammopathy and/or evidence of other organ disease (neuropathy, nephropathy, and cardiomyopathy).