Intestinal Reactive Amyloid A (AA) Amyloidosis in a Patient With Multiple Myeloma: A Case Report and Literature Review

Amyloidosis is a rare group of disorders characterized by the extracellular deposition of misfolded protein aggregates that interfere with the function of the tissue affected. In some patients, the presenting symptom of monoclonal gammopathies, such as multiple myeloma, can be a gastrointestinal bleed with a further report of amyloidosis in gastrointestinal samples. In all the cases the pathology report is read as AL (light chain) amyloidosis. We present a case of a 57-year-old male patient with no medical history who debuted with gastrointestinal bleeding. A colonoscopy revealed a colonic ulcer with a pathologic diagnosis of amyloid A (AA) amyloidosis. Further investigation led to the finding of multiple myeloma (MM) with no evidence of systemic amyloidosis. Although there is little evidence in the literature of the association or even causative relationship between multiple myeloma and AA amyloidosis, our case highlights the importance of searching for an underlying monoclonal gammopathy like MM in a patient with a confirmed diagnosis of AA amyloidosis.