Atypical Presentation of Hereditary ATTR Amyloidosis with Gastrointestinal and Hepatic Manifestations in an 88-Year-Old Woman: A Case Report

BACKGROUND Transthyretin amyloidosis (ATTR) is a systemic condition caused by accumulation of amyloid fibrils in major organs. Mutation in the gene located on chromosome 18, which codes the TTR protein, results in hereditary ATTR, but wild-type mutations can occur with age. Isolated gastrointestinal (GI) and hepatic involvement is uncommon in hereditary ATTR and can mimic malignancy. We describe a rare case of hereditary ATTR amyloidosis with GI and hepatic manifestations in an elderly woman with a history of vaginal carcinoma. CASE REPORT An 88-year-old African American woman with a history of vaginal squamous cell carcinoma presented with abdominal pain and rectal bleeding. Imaging revealed a 6.1×4.6×4.7 cm ascending colon mass, lymphadenopathy, and sub-centimeter bilobar hepatic lesions, all suspicious for malignancy. Colonoscopy demonstrated a near-obstructing necrotic mass. Subsequent endoscopic evaluations revealed amyloid-related vascular involvement and a duodenal neuroendocrine tumor. Surgical resection of colon and liver lesions revealed extensive amyloid deposition, confirmed as transthyretin (ATTR) type via mass spectrometry. Genetic testing identified a pathogenic Val122Ile mutation in the TTR gene. Despite an extensive workup, including echocardiogram, cardiac MRI, and sural nerve biopsy, no cardiac or systemic amyloid involvement was identified. CONCLUSIONS This case highlights a rare presentation of hereditary ATTR amyloidosis with isolated GI and hepatic involvement. The absence of typical systemic features like cardiomyopathy or neuropathy poses diagnostic complexities. Early histopathologic evaluation, mass spectrometry, and genetic testing are essential for accurate diagnosis in patients with atypical amyloid presentation.