Increased number of pseudodrumsticks in neutrophils and large platelets. A "new" congenital leucocyte and platelet morphological abnormality

2 members of a family, a child and his father, showed a combined morphological abnormality of leukocytes and platelets. The abnormality consisted of the presence of pseudodrumsticks in the neutrophils and of large platelets. One or more than one pseudodrumstick was present in about 40% of neutrophils. Leukocyte count, differential count and enzymatic stains were normal. Large platelets constituted about 25% of the platelet population. 1 patient also had mild thrombocytopenia which appeared to be unrelated to the basic defect since it appeared after a parotitis infection. Platelet function was normal but for a moderate prolongation of the bleeding time in the patient who had mild thrombocytopenia. No chromosomal abnormality was present in the propositi. The condition seems different from other leukocyte and platelet abnormalities so far described.