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What are the genetic and acquired risk factors for thrombosis? How is it treated, and what follow-up is required? Two experts offer some answers--and call for additional research. [ABSTRACT FROM AUTHOR]

It is disheartening to make the diagnosis of recurrent respiratory papillomatosis in a young child. This disease presents in the infant or young toddler with symptoms of worsening hoarseness, stridor, and sometimes respiratory distress. Such children will undergo multiple procedures in their lifetimes to clear their airways of papillomas; it is not uncommon to see a child return as many as 60 to 100 times. Otolaryngologists have successfully developed equipment and techniques to maintain an adequate airway in almost all cases of laryngeal papilloma. Unfortunately, achieving a satisfactory voice outcome both in the short term as well as in the long run is a much more difficult problem.

We studied the clinical and biologic features of 10 cases of acute leukemia that met standard French-American-British (FAB) criteria for acute myeloid leukemia (AML) but in which the blast cells also expressed the T-cell-associated CD2 surface antigen. All cases had greater than 3% myeloperoxidase and Sudan black B-positive leukemic blasts, and blasts from seven cases contained Auer rods. Reactivity of the cells with a panel of monoclonal antibodies (MAbs) indicated that leukemic cells in all cases expressed myeloid-associated (CD11b, CD13) surface antigens, further supporting the diagnosis of AML. However, blasts from every patient coexpressed the T-cell-associated surface CD2 and CD7 as well as cytoplasmic CD3 antigens. Blasts from five patients expressed surface CD25, whereas blasts from only one expressed surface CD3. Five patients had rearranged T-cell receptor beta-chain genes, whereas only three had rearranged T-cell receptor gamma-chain genes. This pattern of lineage-related gene expression appears to define a distinct subtype of AML with T-lymphoid features (CD2+ AML) and could reflect either aberrant gene expression in leukemic blasts or transformation of a pluripotent stem cell having a flexible pattern of gene expression. Clinically, these 10 patients presented at an older age with a higher leukocyte count and a higher frequency of lymphadenopathy than did children whose blast cells were characteristic of myeloid leukemia. Patients with CD2+ AML also had poorer responses to remission induction therapy (50% v 80% entered complete remission, P = .05). However, each of the five children who failed induction chemotherapy on AML protocols had a striking response to drug combinations usually reserved for lymphoid leukemia. We conclude that this leukemia with mixed lymphoid and myeloid characteristics is a distinct biologic and clinical entity.

OBJECTIVE: To determine whether resistance to activated protein C caused by the factor V Leiden mutation (Arg^5^0^6 to Gln) is associated with thrombosis occurring during childhood. STUDY DESIGN: Children with thrombosis were screened for activated protein C resistance. Children found resistant to activated protein C had DNA analysis for the factor V Leiden mutation. Family members of the children with activated protein C resistance were similarly studied. RESULTS: Three of fourteen children examined had abnormal normalized activated protein C sensitivity ratios. One child had protein S deficiency. The children had hyperlipidemia. Molecular confirmation of the factor V Leiden mutation was obtained for all three children. Family members of each of the three children were affected. CONCLUSIONS: Children have thromboses in association with the factor V Leiden mutation, as do adults. This mutation may be identified as an isolated risk factor or in association with other risk factors for thrombosis. (J PEDIATR 1996;128:324-8)

OBJECTIVE: The objective of this study was to determine the cause of purpura fulminans, disseminated intravascular coagulation, or thrombosis in seven children with varicella. All children were found to have a lupus anticoagulant and acquired protein S deficiency. Thrombosis in five children was associated with presumed or documented infection with streptococcus. STUDY DESIGN: Coagulation tests included determinations of the activated partial thromboplastin time, the prothrombin time, the dilute Russell viper venom time, the prothrombin F 1+2 fragment, the C4b-binding protein (C4b), total and free protein S antigen, and clotting activities of factors II, V, VII, and X and of protein C and protein S. Autoantibodies to phospholipids, cardiolipin, and protein S were determined in enzyme-linked immunosorbent assays. RESULTS: All children had a lupus anticoagulant and acquired protein S deficiency. Thrombosis in five children was associated with presumed or documented infection with streptococcus. All children transiently expressed free protein S deficiency, elevated levels of IgG, IgM, or both binding to protein S, the lupus anticoagulant, and increased concentration of the F 1+2 fragment. Four children also had antiphospholipid or anticardiolipin antibodies. In one child a purified IgG fraction cross-reacted with both protein S and a specific varicella antigen. CONCLUSIONS: A subset of children with varicella infection, some of whom are coinfected with streptococcus, are prone to development of a lupus anticoagulant and an autoantibody to protein S, which results in acquired free protein S deficiency. Such children are at risk of having life-threatening thrombotic events. (J PEDIATR 1996;128:319-23)