Renal amyloidosis following tuberculosis.

Amyloidosis, either primary or secondary, may be defined as a group of chronic infiltrative disorders that have in common a beta-pleated sheet configuration on X-ray diffraction examination, a fine fibrillar nonbranching appearance on electron microscopy and an apple-green birefringence when examined under polarised light after staining with Congo-red. Renal amyloidosis is a rare entity in the pediatric age group and is almost always secondary in nature, related to chronic infections and inflammatory conditions. It occurs 2-7 years after a chronic inflammatory process; however an onset as early as 9 months of life is known. The diagnosis of amyloidosis is suspected on the basis of clinical features and is established by obtaining an appropriate tissue biopsy and demonstrating amyloid with appropriate stains. All the tissues obtained must be stained with Congo-red stain which is the singlemost useful diagnostic test to define amyloidosis. In order to differentiate the primary from secondary variety, the deposits may be treated with potassium permanganate before Congo-red staining. In secondary amyloidosis, the green birefringence seen under polarized light is abolished. Therapeutic approaches include specific measures to reduce the amyloid deposition and general measures to relieve symptoms related to involvement of specific organs. The prognosis in renal amyloidosis is relatively poor, with a median survival of 9-13 months in primary amyloidosis complicated by renal involvement, and more than 50 months in secondary amyloidosis. We have reported a case of secondary amyloidosis following tuberculosis and have discussed the clinical features, diagnosis and management of amyloidosis.