Background. Klippel-Trenaunay syndrome (KTS) is an overgrowth syndrome associated with capillary/venous/ lymphatic malformations with limb hypertrophy and cancer risk. Various cancers, mostly Wilms tumor, have been reported in patients with KTS, but not leukemia. Chronic myeloid leukemia (CML) is also a rare disease in children, where there is no known disease or syndrome to predispose to CML.

Case. We report a case of CML incidentally diagnosed in a child with KTS when he was bleeding from surgery of the left groin for vascular malformation.

Conclusions. This case reflects the variety of cancer types that may accompany KTS and provides information about CML prognosis in such patients.

Keywords: CVLM syndrome, Klippel-Trenaunay syndrome, PIK3CA gene, chronic myeloid leukemia, overgrowth syndrome, vascular malformation