RT Journal Article SR Electronic T1 Ocular infiltration as initial presentation of acute monocytic leukaemia transformed from chronic myelomonocytic leukaemia associated with BRAF V600E mutation JF BMJ Case Reports JO BMJ Case Reports FD BMJ Publishing Group Ltd SP e228519 DO 10.1136/bcr-2018-228519 VO 12 IS 3 A1 Aditya Tedjaseputra A1 Fathima Shahla Vilcassim A1 George Grigoriadis YR 2019 UL http://casereports.bmj.com/content/12/3/e228519.abstract AB Acute monocytic leukaemia (French-British-American classification: AML-M5b) is characterised by a predominance of cells of the monocytic lineage on bone marrow examination. Furthermore, a discerning feature is its tendency for tissue infiltration. While gum hypertrophy and hepatosplenomegaly are common, ocular involvement is rare. Here, we present a case of a 75-year-old man referred with proptosis and monocytosis—subsequently diagnosed as AML-M5b, whose disease course was distinguished by extensive tissue invasion (ocular, pulmonary, liver, spleen). Cytogenetics and molecular tests were consistent with blastic transformation of previously undiagnosed chronic myelomonocytic leukaemia, supported by the presence of long-standing, low-grade monocytosis. Notably, a BRAF V600E mutation was also detected—an oncogenic driver previously reported in de novo and therapy-related, but not chronic myelomonocytic leukaemia-transformed, AML-M5b. While an initial response to cytoreductive treatment was observed, his tissue-invasive disease soon progressed with worsening pulmonary infiltrates, disseminated intravascular coagulation and renal failure, resulting in death.