To evaluate diagnostic criteria, disease characteristics, and the clinical course of pediatric myelodysplastic syndrome (MDS), we reviewed 327 consecutive cases diagnosed with de novo acute myeloid leukemia (AML) or MDS at St Jude Children's Research Hospital between February 1980 and January 1993. Among 49 cases with <30% marrow blasts (consistent with FAB criteria and common diagnostic practice for MDS), eight had karyotypes associated with de novo AML (four with t(8;21)(q22;q22) and one each with inv(16)(p13q22), t(11;17)(q23;q21), t(9;11)(p22;q13), and i(1)(ql0)). We termed these cases AML with a low blast count (AML-LBC) and compared their clinical and morphologic features with those of the remaining 41 cases. AML-LBC cases had little or no hematopoietic dysplasia. MDS cases consisted of refractory anemia (RA, n=6), RA with ring sideroblasts (n=2), RA with excess blasts (RAEB, n=4), RAEB in transformation (n=14), and chronic myelomonocytic leukemia (n=15). Most had moderate/severe or multilineage hematopoietic dysplasia, with significantly higher dysplasia scores than AML-LBC cases (P=0.007). Only 30% of patients with MDS achieved complete remission (CR) after two cycles of AML-directed therapy, compared with 88% of patients with AML-LBC (P=0.0001); MDS patients tended to experience prolonged severe cytopenias with chemotherapy. The 4-year survival for MDS patients was 23% +/- 7% (s.e.), vs 50% +/- 18% (s.e.) for AML-LBC (P=0.048). AML-LBC patients frequently had chloromas; none were seen in MDS patients. We conclude that the 30% blast threshold is ineffective for separation of AML and MDS in pediatric patients, and that genetic data should be included in this decision process. AML-LBC, defined by <30% blasts in bone marrow and cyto- (or molecular) genetic abnormalities associated with de novo AML, and characterized by absent or mild marrow dysplasia, is biologically and clinically distinct from MDS and should be treated as de novo AML. Outcome in pediatric MDS remains poor, and new treatment strategies are needed for these patients.

Granules in blasts are most typical of acute myeloblastic leukemia. However, there have been scattered reports of patients with acute lymphoblastic leukemia (ALL) that have lymphoblasts with azurophilic cytoplasmic granules. These reports do not describe immunologic markers or cytogenetics. We report five additional cases with detailed cytologic, immunologic, and cytogenetic studies. At diagnosis one of these patients had central nervous system disease, while the others had no unusual features. Four of the five patients attained remission. The blasts of all five patients contained distinct cytoplasmic azurophilic granules. The granules were negative for peroxidase and chloroacetate esterase and positive for PAS, acid phosphatase, alpha-naphthyl acetate esterase incompletely fluoride inhibited, alpha-naphthyl butyrate esterase, and in one case, Sudan black B. In the one patient studied by electron microscopy, characteristic lymphoblasts contained membrane-bound electron lucent inclusions, which stained positively with non-specific esterase. Immunologic markers showed a common ALL phenotype. Different cytogenetic abnormalities were seen in all cases. It is important to recognize the characteristics of this morphologic subtype of ALL in order to avoid a misdiagnosis of acute nonlymphocytic leukemia.

The authors observed Auer rods in mature neutrophils, bands, and metamyelocytes in two children with AML with maturation (FAB M2). In order to determine if this rare finding was characteristic of AML M2, the authors reviewed the bone marrows and peripheral blood smears of 50 children with AML M2 and 50 children with other AML subtypes (FAB M1, M3, M4, and M5). They found Auer rods in mature neutrophils and band forms in 10 of 50 patients (20%) with AML M2 but in none of 50 patients with non-M2 AML. This finding was not related to the frequency of mature cells in the specimen or to the frequency of Auer rods in blasts. Cytogenetics did not show a consistent abnormality. The presence of Auer rods in mature granulocytes is unique to FAB M2 AML in the authors' series and supports the concept that in AML at least some of the mature myeloid cells are involved in the leukemic process.

Abstract. Tumoral calcinosis is presently a poorly defined disease. In its classic form, it consists of multiple large foci of benign mineralization in the soft tissuc adjacent to bone near large joints. Patients are generally of African descent and are adolescents or young adults at presentation. Both metabolic and traumatic etiologies have been proposed. We report six adult Caucasian patients with lesions that pathologically resembled tumoral calcinosis. All lesions were small (less than 3 x 3 cm) and were located along the proximal 1inca aspera of the femur. All patients presented with pain. Because of the atypical patient population and the unusual size and location of the lesions, we refer to this process as a "tumoral calcinosis-like lesion." A typical radiographic appearance and location, together with appropriate clinical history, can strongly suggest this diagnosis.

The zoosporic phase of the water mould Achlya heterosexualis, initiated when zoospores emerge from cysts, is strongly influenced by cations. The concentrations of Ca2+ and K+ present in the medium can determine whether or not zoospores will be released from cysts, whether zoospore motion will be approximately linear or circular, rapid or slow, and when zoospore activity will be terminated by encystment. Ionic effects on zoospore motility are rapid and reversible over short time spans; within a 2 min period motility can be strongly suppressed by increasing the [K+] and then restored by increasing the [ Ca2+]. Trifluoperazine, considered to be an anti-calmodulin drug, both inhibits zoospore release, and arrests zoospore motility.