Our understanding of LCH has improved in the last 20 years. Available treatment regimens can control the disease in the majority of patients. The discovery of novel driver mutations and the development of targeted therapy promise better outcomes with fewer long-term therapy-related adverse events, particularly for pediatric and adolescent patients.

A case of juvenile myelomonocytic leukemia (JMML, previously referred to as JCML) in a neonate with Noonan syndrome (NS) is described. The boy presented with bilateral congenital hydrothoraces, nonimmune hydrops, dysmorphic facies, persistent thrombocytopenia, and leukocytosis. The diagnosis of JMML was made on bone marrow cell culture studies. Review of the literature reveals an unusual preponderance of hematologic malignancies, in particular JMML, among patients with NS. Of 40 NS patients admitted to the authors' institution during a 10-year period, there were 4 (10%) with evidence of a monocytic proliferation, which resolved spontaneously. The authors postulate that patients with NS may have an increased incidence of myeloproliferative disorders, which in most cases appears to be benign but may be preleukemic or even lethal.

Two brothers with presumed Baller‐Gerold syndrome, one of whom was previously diagnosed with the association of vertebral, cardiac, renal, limb anomalies, anal atresia, tracheo‐esophageal fistula (VACTERL) association with hydrocephalus, were evaluated for chromosome breakage because of severe thrombo cytopenia in one of them. Spontaneous and clastogen‐induced breakage was markedly increased in both patients as compared to control individuals. Clinical manifestations and chromosome breakage, consistent with Fanconi anemia, in patients with a prior diagnosis of either Baller‐Gerold syndrome, reported earlier in one other patient [Farrell et al., 1994: Am J Med Genet 50:98–99], or with VACTERL association with hydrocephalus, recently reported in 3 patients [Toriello et al., 1991: Proc Greenwood Genet Center 11:142; Porteus et al., 1992: Am J Med Genet 43:1032–1034], underline the clinical heterogeneity of Fanconi anemia and raise the question of whether these syndromes are distinct disorders or phenotypic variations of the same disease. © 1995 Wiley‐Liss, Inc.

Allogeneic BMT offers a potential cure for patients with agnogenic myeloid metaplasia. A preparatory regimen containing busulfan and cyclophosphamide appears promising for patients with the disease.