Acute megakaryoblastic leukemia simulating carcinoma.

Acute megakaryoblastic leukemia has emerged as an important subset of early childhood leukemia. It often presents a diagnostic dilemma because of its many morphologic manifestations and propensity to mimic metastatic carcinoma. An abdominal mass was identified by sonographic and computed tomographic scans in a 10-month-old girl, who had anemia and thrombocytopenia. An open biopsy of the 3-cm, peripancreatic mass showed cohesive nests and sheets of tumor cells with focal spindling and desmoplasia. Although the diagnosis of acute megakaryoblastic leukemia was established from a bone marrow aspirate using immunocytochemical techniques and karyotype analysis, a coexistent abdominal epithelial malignant neoplasm could not be excluded entirely by light microscopic examination alone. The megakaryoblastic nature of the abdominal tumor was established by immunocytochemical stains for glycoprotein IIIa on paraffin-embedded tissue.

Lethal cytomegalovirus infection in preterm infants: clinical, radiological, and neuropathological findings.

Fifteen premature infants with lethal congenital cytomegalovirus infection were studied to determine the clinical, neuroradiological, and neuropathological characteristics of the disease in this population. Nine infants were liveborn but died at a postnatal age of 18 +/- 21 days; 6 infants were stillborn. Clinical findings in liveborn infants included microcephaly (77%), seizures (55%), hypotonia (33%), and multiple contractures (18%). Ophthalmological findings included chorioretinitis, optic atrophy, and corneal opacities. Neuroradiological findings included the postnatal evolution of periventricular calcification in 1 infant, and cerebellar hypoplasia diagnosed by magnetic resonance imaging in 1 infant. Neuropathological findings included periventricular necrosis and calcification (12), associated diffuse calcification frequently involving the convexity of the gyri (6), cerebellar hypoplasia (5), periventricular leukomalacia (2), intraventricular hemorrhage (2), hydrocephalus (2), and porencephalic cyst (1). Intranuclear inclusion bodies within the brain were observed in 4 infants, whereas systemic inclusion bodies were present in all infants. These data indicate several atypical findings in preterm infants rarely reported in term infants, including hypotonia, multiple contractures, periventricular leukomalacia, and optic atrophy.

Metabolic tolerance to arginine: implications for the safe use of arginine salt-aztreonam combination in the neonatal period.

Two similar cohorts of low birth weight infants whose size was appropriate for gestational age randomly received either aztreonam-arginine plus ampicillin (n = 15) or gentamicin plus ampicillin (n = 15) for empiric treatment of neonatal sepsis. The regimens were infused together with glucose at greater than 5 mg/kg per minute, and immediate (4 hours) and cumulative (3 days) effects were assessed. Serum arginine and insulin values rose immediately after administration of aztreonam (containing 0.15 mmol of arginine per kilogram), but there were no changes in the gentamicin-treated cohort; no differences occurred in either cohort in serum concentrations of glucose, ammonia, potassium, creatinine, and bilirubin. After 3 days of antibiotic therapy (n = 13), the baseline serum arginine concentration was almost twice as high in the aztreonam group and showed a similar further rise and fall during the 4 hours after infusion; arginine urinary fractional excretion (normalized to creatinine clearance) decreased in the gentamicin group. The indirect bilirubin concentration rose more (p less than 0.001) in the aztreonam-treated infants (5.1 to 11.5 mg/dl (87 to 196 mumol/L] than in the gentamicin-treated infants (5.5 to 8.1 mg/dl (94 to 138 mumol/L)). Thus a modest differential bilirubin response and modestly elevated baseline serum arginine level occurred after the 3-day low-arginine doses of this study; serum ammonia and glucose concentrations were not affected. Aztreonam-arginine in neonates was well tolerated metabolically, and we believe that it can be used safely in conjunction with attention to glucose and bilirubin metabolism.

Differential expression of the two human arginase genes in hyperargininemia. Enzymatic, pathologic, and molecular analysis.

Previous studies in our laboratory and others have demonstrated in humans and other mammals two isozymes of arginase (AI and AII) that differ both electrophoretically and antigenically. AI, a cytosolic protein found predominantly in liver and red blood cells, is believed to be chiefly responsible for ureagenesis and is the one missing in hyperargininemic patients. Much less is known about AII because it is present in far smaller amounts and localized in less accessible deep tissues, primarily kidney. We now report the application of enzymatic and immunologic methods to assess the independent expression and regulation of these two gene products in normal tissue extracts, two cultured cell lines, and multiple organ samples from a hyperargininemic patient who came to autopsy after an unusually severe clinical course characterized by rapidly progressive hepatic cirrhosis. AI was totally absent (less than 0.1%) in the patient's tissues, whereas marked enhancement of AII activity (four times normal) was seen in the kidney by immunoprecipitation and biochemical inhibition studies. Immunoprecipitation-competition and Western blot analysis failed to reveal presence of even an enzymatically inactive cross-reacting AI protein, whereas Southern blot analysis showed no evidence of a substantial deletion in the AI gene. Induction studies in cell lines that similarly express only the AII isozyme indicated that its activity could be enhanced severalfold by exposure to elevated arginine levels. Our findings suggest that the same induction mechanism may well be operative in hyperargininemic patients, and that the heightened AII activity may be responsible for the persistent ureagenesis seen in this disorder. These data lend further support to the existence of two separate arginase gene loci in humans, and raise possibilities for novel therapeutic approaches based on their independent manipulation.

The identification of fungal casts. A new method for diagnosing visceral candidiasis.

Visceral candidiasis is a potentially life-threatening infection that is difficult to diagnose clinically. Existing laboratory methods do not adequately distinguish visceral candidiasis from extensive candidal infections of mucosal surfaces. A new laboratory method, the detection of fungal casts in urine sediment, permits the unequivocal diagnosis of renal candidiasis. Since the severity of renal candidiasis varies, the clinical significance attributed to the identification of fungal casts in the urine must be based upon a complete assessment of the patient. The ultimate utility of the fungal cast method will depend upon the incidence with which fungal casts can be identified in the urine of patients with renal candidiasis. At present, this incidence is unknown. However, the method has been clinically useful in a number of specific cases and should not be overlooked in evaluating patients with candiduria in whom the diagnosis of visceral candidiasis is suspected but not confirmed.

Identification of fungal casts in a patient with renal candidiasis.

Since the treatment of fungal infections with amphotericin B may result in significant nephrotoxicity, better methods for discriminating between life-threatening and more benign fungal infections are needed. Recently numerous fungal casts were identified in the urine of a patient who had undergone renal allograft transplantation. The recognition of fungal casts permitted an unequivocal diagnosis of systemic fungal infection. Successive examinations of the patient's urinary sediment provided an excellent monitor of the response to treatment. The cytologic features of fungal casts are described. Since systemic fungal infections often involve the kidney, screening for fungal casts may have significant clinical applicability.