Thrombocytosis distinguishes POEMS syndrome from chronic inflammatory demyelinating polyneuropathy

POEMS (polyneuropathy, organomegaly, endocrinopathy, monoclonal plasma cell disorder, and skin changes) syndrome may be mistaken for chronic inflammatory demyelinating polyneuropathy (CIDP). Differentiating the 2 entities is crucial, as there are major treatment implications.We compared platelet counts in 136 POEMS patients and 67 CIDP controls.Of the patients with POEMS, 53.7% had thrombocytosis, compared with 1.5% of those with CIDP (P < 0.0001). The median platelet count in patients with POEMS was 467,000/μl compared with 275,000/μl in those with CIDP (P < 0.0001).Thrombocytosis is a helpful indicator to prompt clinicians to consider the diagnosis of POEMS syndrome in patients who are thought to have CIDP, and is an important reminder of the increased risk of thrombotic events in POEMS syndrome.