A 17-year-old boy, with acute myelomonocytic leukemia and inversion 16(p13q22) developed polyneuropathy and isolated central nervous system relapse. Scoliosis and high-arched feet suggested a diagnosis of Charcot Marie Tooth (CMT) syndrome and genetic testing confirmed duplication at the PMP22 locus at chromosome 17p11.12. No mutation was found in another CMT gene, the CMT C1 LITAF locus at 16p13.2, to suggest that this association is anything more than chance. Titres to VGKC, a paraneoplastic autoantibody, were elevated, suggesting an additional mechanism for the polyneuropathy. This case extends the clinical spectrum of cancer with CMT, and of paraneoplastic disorders.