Juvenile Xanthogranuloma — SCE Dermatology MCQ

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HardPaediatric DermatologyJuvenile XanthogranulomaSCE Dermatology

A 10-year-old boy presents with multiple juvenile xanthogranulomas (JXG). He has yellowish-orange papules and nodules on his trunk. Biopsy shows Touton giant cells (wreath of nuclei surrounding a central eosinophilic zone with peripheral foamy cytoplasm). What is the most important systemic association to screen for?

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Correct answer: B — Neurofibromatosis type 1 (particularly the combination of JXG + NF1 + juvenile chronic myelomonocytic leukaemia)

The correct answer is B, neurofibromatosis type 1 (particularly the combination of JXG plus NF1 plus juvenile chronic myelomonocytic leukaemia). Multiple JXG lesions in a child should prompt screening for NF1, since up to 10 percent of NF1 patients develop JXG, and this triad carries a markedly increased risk of juvenile myelomonocytic leukaemia (JMML), a rare but aggressive childhood myeloproliferative disorder. The mechanism relates to dysregulated RAS-MAPK signalling from NF1 (neurofibromin) haploinsufficiency, which predisposes to both non-Langerhans cell histiocytic proliferation and clonal myeloid transformation. Touton giant cells confirm the histiocytic, foam-cell nature of JXG but are not specific to any single systemic association, making clinical correlation with skin stigmata of NF1 (cafe au lait macules, neurofibromas, freckling) essential. Any child with multiple JXG, especially with NF1 features, warrants clinical assessment and full blood count monitoring for JMML.

Reference: https://www.nice.org.uk/guidance/conditions-and-diseases/skin-conditions