Gastrointestinal ALκ amyloidosis presenting as protein-losing enteropathy correctly diagnosed by immunohistochemistry using amyloid-type-specific antibodies.

A 54-year-old man presented with protein-losing enteropathy. Biopsies from the stomach, duodenum, ileum and colon showed deposits of amyloid. The bone marrow showed plasmacytosis. After an initial misdiagnosis of AA amyloid, a revised diagnosis of ALκ amyloidosis was made at an expert referral laboratory. Care must be taken in the use of antibodies and proper controls in the performance and interpretation of immunohistochemistry for amyloidosis. A wide panel of amyloid-type-specific antibodies must be used and interpreted in comparative mode to avoid misdiagnosis. Natl Med J India 2015;28:129–31