Nerve ultrasonography findings as possible pitfall in differential diagnosis between hereditary transthyretin amyloidosis with polyneuropathy and chronic inflammatory demyelinating polyneuropathy.

Hereditary transthyretin amyloidosis with polyneuropathy (ATTRv-PN) is a rare form of treatable severe progressive sensory-motor and autonomic polyneuropathy. Albeit usually axonal, late-onset ATTRv-PN can show clear demyelinating features at electrodiagnostic studies, sometimes fulfilling CIDP diagnostic criteria. High-resolution nerve ultrasonography (HRUS) is an emerging useful supportive tool in the diagnosis of CIDP. Herein, we present a late-onset ATTRv-PN patient in which both clinical-neurophysiological and HRUS features could have led to a CIDP misdiagnosis. Nerve alterations at HRUS and MRI have already been reported in ATTRv-PN, albeit not in ATTRv-PN patients with clinical and electrodiagnostic features of CIDP. Our case shows that ATTRv-PN could present the same morphological nerve alterations pattern of CIDP at ultrasonography, adding HRUS findings as a further source of misdiagnosis late-onset ATTRv-PN.