To highlight the importance of using more sensitive imaging modalities when skeletal x-rays are negative and there is a high suspicion for POEMS syndrome, in order to avoid diagnostic delay and worsening  neurologic function.

POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, skin changes) is a rare paraneoplastic disorder. Mandatory diagnostic criteria include polyneuropathy and a monoclonal plasma cell disorder. Osteosclerotic bone lesions, typically found on x-ray, are a major criteria for diagnosis. The polyneuropathy of POEMS is typically demyelinating, mimicking chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). Unlike CIDP, which is treated with immunotherapy, POEMS is treated with chemotherapy, radiation, and/or bone marrow transplant.

Patient 1 is a 48-year-old man who presented with a diagnosis of CIDP which was treated with IVIg, mycophenolate mofetil, and prednisone with no symptom improvement for 1 year. Initially, a lambda monoclonal gammopathy was present, VEGF elevated but < 200 pg/mL, and skeletal x-ray negative. Due to continued poor response to therapy, a CT scan was performed which revealed a pelvic bone lesion consistent with plasmacytoma. The patient’s severe neuropathy is now improving after bone marrow transplant.

Patient 2 is a 28-year-old woman who presented with a diagnosis of CIDP which was treated with IVIg and rituximab with no symptom improvement for 6 months. Initially, lambda monoclonal gammopathy was present, VEGF negative, and skeletal x-ray negative so the patient was continued on treatment for CIDP with no improvement. Due to continued clinical suspicion, a PET scan was finally performed showing a destructive rib lesion with pathology consistent with plasmacytoma. She is currently receiving radiation therapy.

POEMS syndrome is a debilitating disease where misdiagnosis can potentiate poorer patient outcomes. When there is a high clinical suspicion, a negative skeletal x-ray should be followed by more sensitive imaging modalities so that this diagnosis is not missed.