FGFR1 translocation with concurrent myeloproliferative neoplasm, systemic mastocytosis, and lymphoblastic lymphoma: a...

FGFR1 translocation may cause myeloid or lymphoid neoplasm but rarely systemic mastocytosis (SM). Conversely, SM is associated with myeloproliferative neoplasm (MPN) but rarely lymphoblastic lymphoma (LBL) or FGFR1 translocation. We report the first case of FGFR1 translocation in a patient with concurrent LBL, MPN, and SM. A 21-year-old male patient presented with diffuse lymphadenopathies and leukocytosis. TdT⁺/cytoCD3⁺/CD79a^weakly+ LBL was identified in the lymph node. Bone marrow had MPN, SM, and TdT⁺/CD79a⁺/cytoCD3^weakly+ LBL. The cytogenetic study, reverse-transcription polymerase chain reaction, and sequencing revealed t(8;13)(p11;q12) involving FGFR1 and ZMYM2. Under the hyper-cyclophosphamide, vincristine, doxorubicin, and dexamethasone regimen, complete remission of LBL was achieved despite persistent MPN and SM in the bone marrow. This rare case implies FGFR1 translocation in a precursor cell capable of differentiation into mast cells and lymphoblasts, strengthening the relationship between the 2 tumors in the World Health Organization classification: myeloid and lymphoid neoplasms with FGFR1 abnormalities, and SM with an associated hematologic neoplasm.