Case Presentation: A 67-year-old Fijean woman presented to the emergency department with three weeks of fevers, chills, weakness, watery non-bloody diarrhea, and unintentional 15lb weight loss. She had no recent travel, sick contacts, changes in dietary habits, antibiotic use, or initiation of new medications. Physical exam was significant for epigastric tenderness and hepatomegaly.
Her laboratory evaluation demonstrated a white blood cell count of 36,000/uL, hemoglobin of 9 g/dL, creatinine of 4.27 mg/dL, albumin of 1.6 g/dL, and procalcitonin of 95. Abdominal CT showed small bowel mesenteric fat stranding, colonic wall thickening and pericolonic fat stranding. An EGD and colonoscopy were performed, which showed amyloidosis of the esophagus, stomach, duodenum, cecum, and colon. Bone marrow biopsy showed no evidence of malignancy, and amyloid typing revealed AA subtype amyloidosis. Infectious studies, including HIV, sputum acid fast bacilli and mycobacterium tuberculosis (MTB) PCR of the sputum and endoscopic biopsies were negative, but Quantiferon was indeterminate. She did not have history or clinical findings consistent with chronic rheumatologic illness, and so PET-CT was performed to evaluate for occult malignancy or infection. This revealed FDG-avid lymphadenopathy in the right neck, left axilla, and pelvis.
An excisional biopsy of three axillary lymph nodes was performed, which showed necrotizing granulomas with 1/3 lymph nodes positive for MTB. The patient was started on anti-tuberculosis therapy.
Discussion: AA amyloidosis occurs as a result of fibril deposition composed of serum Amyloid A, an acute phase reactant, from chronic inflammation related to infection, rheumatologic or autoimmune conditions, or malignancy. Early proteinuric renal involvement as well as gastrointestinal and liver involvement are common while cardiac or neurologic involvement tends to be rare. Epidemiologically, rheumatologic illness and inflammatory bowel disease are more common causes in the U.S., while infectious etiologies such as MTB are seen more in the developing world. AA amyloidosis is ultimately treated by addressing the underlying condition causing chronic inflammation.
The initial survey did not reveal evidence of active MTB infection, and so subsequent testing focused on occult malignancy as the probable cause of amyloidosis. While tuberculous lymphadenitis is one of the more common forms of extra-pulmonary tuberculosis, her presentation was additionally peculiar as she was immunocompetent.
Conclusions: The hospitalized patient with multi-organ injury invites a wide differential. While uncommon, AA amyloidosis should be an important consideration, particularly in patients who have chronic illness or limited contact with the medical system. With an increasing number of these patients in the hospital setting, early recognition of amyloidosis by hospitalists is critical to identify the underlying cause and alter the disease course.