# Neurological Peculiarities of POEMS Syndrome: Experience From a Brazilian University Center

## TL;DR

This study examines the neurological features of POEMS syndrome in a Brazilian cohort, highlighting unique electrophysiological patterns and diagnostic delays.

## Contribution

The study identifies atypical electrophysiological features and a high proportion of IgG paraprotein in a Brazilian POEMS syndrome cohort.

## Key findings

- 96% of patients had demyelinating polyneuropathy with axonal damage, and 33% showed conduction block.
- 73% of patients had IgG subtype monoclonal paraprotein, and 91% had lambda light chain.
- Only 6% of patients were diagnosed with Castleman disease, lower than previously reported cohorts.

## Abstract

Polyneuropathy, organomegaly, endocrinopathy, monoclonal protein, and skin changes (POEMS) syndrome is a rare paraneoplastic syndrome associated with significant neurologic morbidity. Better understanding of the manifestations of this disease is crucial to early diagnosis and improvement of prognosis.

We retrospectively reviewed medical record data of adult patients diagnosed with POEMS syndrome between 2007 and December 2023 fulfilling the 2014 International Myeloma Working Group criteria for POEMS syndrome in a single tertiary care Hospital in Brazil. Clinical, laboratory and electrophysiological data were analyzed.

Thirty‐three patients were included, with median time from symptom onset to diagnosis of 13 (11–35) months, and 30% of patients were nonambulatory at the diagnosis. Neuropathy was present in 100% of patients, and early proximal muscle weakness was present in 57%. Nerve conductions studies (NCS) disclosed demyelinating polyneuropathy with axonal damage in 96% and conduction block in 33%. Serum monoclonal paraprotein heavy chain was IgG subtype in 73% and lambda light chain in 91%. Castleman disease was diagnosed in 6% of patients. Organomegaly, bone lesions and endocrinological profiles were similar to previously reported cohorts.

Patients in our cohort had similar clinical profiles to previously reported data. However, unlike other large cohorts, our study showed a high proportion of IgG class paraprotein, non‐length‐dependent findings and conduction block on electrophysiology, and a lower number of cases associated with Castleman's disease. Our findings highlight the importance of pursuing a POEMS syndrome diagnosis even in the presence of atypical electrophysiological features.