Rosai-Dorfman Disease Presenting as Isolated Tonsillar Asymmetry in an Indian Diaspora Man with Ulcerative Colitis, UK

Key finding

> Histopathology showed large histiocytic cells with prominent emperipolesis, positive for S100 and CD68, negative for CD1a — the diagnostic signature of Rosai-Dorfman disease (RDD), a rare non-Langerhans cell histiocytosis that the WHO reclassified as a histiocytic neoplasm in 2022 after recurrent MAPK-pathway mutations were identified in 30–50% of cases. RDD classically presents with massive, painless cervical lymphadenopathy. This patient had none of that — no palpable nodes at all — and instead presented with isolated, asymmetric tonsillar enlargement without lymphadenopathy. The authors state this appears to be the first reported case of RDD presenting this way; three prior reports described tonsillar involvement only alongside other manifestations (cervical lymphadenopathy, nasal polyps). Multidisciplinary follow-up subsequently found lung nodules (respiratory medicine) and cutaneo

Framework connections: The Immune Priming, The Signal Fire (IL-6)

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