Two cases of polycythemia vera (PV) had transition to a hematological condition compatible with chronic neutrophilic leukemia (CNL) 17 and 8 years after diagnosis, respectively. One patient was treated with carboquone followed by hydroxyurea (HU) and the other with HU during PV phase. On transition, both had neutrophilia with white blood cell count above 40,000/microl, elevated neutrophil alkaline phosphatase activity, splenomegaly, normal karyotype without bcr-abl rearrangement. Busulfan was temporally effective in controlling the neutrophil count. However, one patient progressed to the so-called spent phase and the other subsequently had multiple transitions between PV and CNL. These cases may represent a form of uncommon evolution of PV and support the contention that CNL is a type of myeloproliferative disorder and that at least some CNL cases have derangement at the hematopoietic stem cell level.

Different subtypes of acute myelogenous leukemia have distinct clinical presentations and courses. The specific clinical and molecular aspects of these leukemias have helped modify and create specific strategies for their management. We observed an increased incidence of pulmonary complications in patients with acute myelomonocytic leukemias (AMML) with inversion of chromosome 16 [inv(16)] irrespective of the presence of hyperleukocytosis. We reviewed patient records available over a period of 12 years at The Cleveland Clinic Foundation of patients with AMML with inv(16) and compared the incidence of pulmonary complications to a matched control group of patients with AMML but without inv(16). We found an increased incidence of pulmonary complications in the AMML with inv(16)group when compared to the control group. Two of these patients demonstrated brochiolitis obliterans with organizing pneumonia (BOOP) on lung biopsy. No specific etiology for the pulmonary complications was identified. These findings represent the first observation of an association between WHO-AMML with inv(16) [FAB-AML M4 with inv(16)] with a pulmonary syndrome at presentation. BOOP should be suspected in these cases. A larger prospective study to evaluate this association is warranted.