In 100 untreated patients with chronic lymphocytic leukaemia (CLL) lymphocyte doubling time (LDT) has been investigated in relationship with clinical stages, bone marrow histological patterns, treatment-free period and survival. Although partially correlated with clinical stages and bone marrow patterns, LDT has a clear prognostic significance by itself: whereas a LDT of 12 or less months identifies a population of patients with poor prognosis, a LDT higher than 12 months is indicative of good prognosis as substantiated by a long treatment-free period and survival. This simple parameter can be useful in the clinical management of CLL patients.

Two siblings developed a myeloproliferative disease. One of them was a 9‐year‐old girl with a short history of bleeding, whose initial clinical and hematologic features were concordant with idiopathic myelofibrosis. Shortly afterwards this disorder evolved to a leukemic phase which subsequently resulted in the death of the patient. Four years later, at the age of 16, her brother was diagnosed as having acute myelofibrosis, and some months afterwards he died from fulminant pneumonia coincidently with pancytopenia and presence of scarce blast cells in peripheral blood. From the pathogenetic point of view, neither exposure to bone marrow toxins nor bone marrow chromosome abnormalities could be detected. HLA‐typing disclosed the same haplotype (A2, A9, B5, B21, C5) in both patients.