Neurofibromatosis 1 (NF1) is a common autosomal dominant disorder in which affected children have an approximate 200-fold greater risk of developing juvenile chronic myeloid leukemia (JCML) compared with children without NF1.1,2 A recent article in the Archives3 presented the results of a statistical analysis from a compilation of case reports suggesting that children with NF1 have an even higher risk of JCML (>20-fold) if they concurrently have juvenile xanthogranuloma (JXG). Although case reports are useful for generating hypotheses, because case reports are not drawn from defined populations and do not include representative comparison groups they cannot be used to test for the presence of valid statistical associations.4 The methodological limitations of such a case report analysis coupled with an apparent overestimate of the disease probabilities used by Zvulunov et al3 raise several concerns. They estimate the frequency of NF1 to be between 1 per 2500 and
Gutmann DH, Gurney JG, Shannon KM. Juvenile Xanthogranuloma, Neurofibromatosis 1, and Juvenile Chronic Myeloid Leukemia. Arch Dermatol. 1996;132(11):1390. doi:10.1001/archderm.1996.03890350134028
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