Recurrent Sterile Polyserositis Reveals an Underrecognized Autoinflammatory Phenotype in MECP2 Duplication Syndrome.
Danielle Mendonca, Matt S Zinter, Sunjay R Devarajan et al.
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Case in brief
In a retrospective multicenter review of four patients with MECP2 duplication syndrome, each developed recurrent pleural and/or pericardial effusions with systemic inflammation, including leukocytosis, elevated C-reactive protein, and, in some cases, hyperferritinemia. Extensive investigations did not identify an infectious or oncogenic cause. Immune testing showed abnormalities such as hypogammaglobulinemia and altered lymphocyte populations. Effusions persisted despite antimicrobials and drainage but resolved with immune-directed treatment; one patient had sustained remission during long-term immunomodulatory therapy.
What made this case unusual
Recurrent sterile polyserositis, not previously recognized as an inflammatory manifestation of MECP2 duplication syndrome, occurred alongside evidence of immune dysregulation and responded to immunomodulatory therapy.
Diagnostic / clinical pearl
In MECP2 duplication syndrome with recurrent pleural or pericardial effusions and systemic inflammation, consider an autoinflammatory phenotype when investigations for infection and malignancy are unrevealing; immune phenotyping may help characterize the dysregulation.
Why it matters
The report raises the possibility that immune dysregulation in MECP2 duplication syndrome extends beyond susceptibility to infection, while prospective studies are needed to establish the phenotype and its management.