Pachymeningeal Involvement in POEMS Syndrome: Longitudinal Follow-Up Study and Correlation With Therapeutic Response.

BACKGROUND AND AIMS: Brain pachymeningeal thickening (PT) is common in POEMS (Polyneuropathy, Organomegaly, Endocrinopathy, Monoclonal gammopathy, Skin changes) syndrome. Objective of our study was to assess PT changes in POEMS and correlation with hematologic and neurological response.

METHODS

We performed a longitudinal brain MRI study on 18 POEMS patients. Inflammatory Neuropathy Cause and Treatment (INCAT) disability score assessed neurological impairment. Hematologic response was defined based on accepted criteria. Neurological and hematologic evaluations were performed the same week as brain MRI.

RESULTS

Median disease duration at first MRI was 2 months (range 0-42). Median follow-up between first and last MRI was 44 months (range 3-167). At first MRI, 17/18 patients displayed PT. Twelve patients received bortezomib, 10 lenalidomide, 6 autologous stem-cell transplantation, 3 had ≥ 3 lines of therapy. The overall hematologic response was 72% with 44% achieving complete response. PT remained stable in 10 patients while decreased in 7 patients: all hematologically improved, 83% also neurologically improved. Among the 13 patients with hematologic improvement, 61% showed PT reduction. Among the 8 patients with neurological improvement, 63% displayed PT decrease.

INTERPRETATION: PT is a common feature in POEMS syndrome and may support diagnosis. However, its evolution does not reliably reflect treatment response, limiting its use as a monitoring biomarker.