Objectives Hereditary Transthyretin (ATTR) amyloidosis is a genetic disorder where insoluble amyloid fibrils deposit in heart, nerves and various musculoskeletal tissues. Early recognition of TTR-FAP is important as new genetic therapies become available.

Design We present one confirmed and one clinical case of ATTR deposition in ligamentum flavum causing lumbar canal stenosis.

Subjects The first case is a 44-year-old female with TTR 184S heterozygous mutation who developed urinary urgency and bilateral leg pain exacerbated by walking. Neurological examination was normal. MRI lumbar spine showed a disc bulge in combination with ligamentum flavum thickening at L2/3 causing stenosis of the vertebral canal. She had a laminectomy of the L2/3 level. Histopathological analysis of the surgical tissue was positive on Congo red staining for amyloid and immunohistochemically identified as TTR type. The second case is a 68-year-old man with TTR V122I heterozygous mutation. He presented with paraesthesia from the knees to dorsum of the feet. On examination, power was normal and he had a length dependent neuropathy. A CT myelogram demonstrated spondylosis at L4/5 and L3/4 from disc bulge and marked flaval hypertrophy causing canal stenosis. He was placed on the waitlist for L4-5 decompression but unfortunately died prior to surgery.

Conclusions Identifying ATTR in surgical specimens may diagnose hereditary amyloidosis in otherwise asymptomatic patients and in the future, provide early access to effective therapies.