Castleman Disease Variant POEMS Syndrome Presenting as Polyradiculoneuropathy in a Child: A Case Report.

POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, monoclonal protein, skin changes) is a rare multisystemic disorder linked to plasma cell abnormalities, typically affecting adults. Pediatric cases are extraordinarily rare, with the youngest previously reported patient being 10 years old. We present the case of a 6-year-old boy whose symptoms included progressive lower limb weakness, lymphadenopathy, and thrombocytosis. Initially misdiagnosed as Guillain-Barré syndrome, the finding of lymphadenopathy revealing Castleman disease along with hyperpigmentation, hypertrichosis, papilledema, and hepatomegaly confirmed the diagnosis. Despite the absence of monoclonal protein and sclerotic bone lesions, the multidisciplinary approach led to successful treatment with corticosteroids, thalidomide, and cyclophosphamide, resulting in full remission. This case highlights the diagnostic challenges of POEMS syndrome in children, given its heterogeneity and overlap with other conditions. Early recognition is crucial, as pediatric patients show favorable prognosis with prompt and appropriate treatment.