Chronic Myeloid Leukemia Arising in a Patient of Neurofibromatosis Type 1

Neurofibromatosis type 1 (NF1) represents a major risk factor for development of malignancies, particularly malignant peripheral nerve sheath tumors (MPNST), optic gliomas, other gliomas, and leukemia. We report an unusual case of chronic myeloid leukemia (CML), developed in a patient of NF1. A 40-year-old Indian male, clinically manifesting NF1 since his childhood, presented with huge splenomegaly. Patient also had a large tumor mass arising in a café-au-lait spot on lower back with rapid growth in last 6 months. Excision of this tumor was done, and it turned out to be a diffuse neurofibroma histologically. Peripheral smear was also done in view of splenomegaly, which showed features of chronic myeloid leukemia. CML rarely co-exists with NF1, and there are a very few reports of such cases. It is important to be aware of the possibility that not only the malignant change in benign PNST is more common in these patients, but also other malignancies like CNS tumors and hematolymphoid neoplasm do occur with increased frequency.