Release of leukotriene C4 by isolated, perfused rat small intestine in response to platelet-activating factor.

We reported a rat model of necrotizing enterocolitis by injecting platelet-activating factor (PAF) into the mesenteric vascular bed, and suggested that leukotrienes (LT) are secondary mediators. The present study, using isolated, buffer-perfused rat small intestine, shows: Isolated, perfused small intestine synthesizes LTs in response to PAF. Leukotriene C4 (LTC4) was the predominant LT released. The initial vasoconstriction after PAF injection was due to a transient release of LTC4 since FPL 55712 pretreatment abolished the vasoconstriction. The sustained rise in perfusion pressure was also blocked by FPL 55712, which suggests that other vasoconstrictors released are regulated by LTs. The vasoconstrictor(s) responsible for sustained rise in perfusion pressure is unknown, but is not thromboxane. Most of the LT was released from intestinal tissue rather than mesenteric arteries. Vasodilating prostaglandins (PGs) were also released, probably secondary to LTs. The complex interaction of these lipid mediators (PAF, LTs, and PGs) and their subtle balance may affect the course of the disease.

Flow and image cytometric DNA analysis in rhabdomyosarcoma.

Rhabdomyosarcoma is the most common malignant soft-tissue tumor in childhood, with an overall 3-year disease-free survival of 73%. DNA content is known to correlate with prognosis and therapy response in many cancers. To determine the role of DNA content in rhabdomyosarcoma, 23 tumor samples were studied retrospectively: 18 primary tumors and 5 post-chemotherapy recurrences or specimens obtained at second-look surgeries. The DNA analysis was performed on disaggregated paraffin-embedded tissue nuclei by flow and image cytometry and correlated with the histology and clinical history. Of the primary tumors 4 were diploid, 4 polyploid, and 10 aneuploid (9 with a single aneuploid G0G1 peak and 1 multiploid) by flow cytometry. The concordance rate between flow and image cytometry was 19 of 23 (83%); one case did not have flow cytometry available. Most embryonal rhabdomyosarcomas were aneuploid (10 of 12; 83%), and they had a high incidence of recurrence in Stages III and IV (4 of 12; 33%). Although aneuploidy in pediatric cancers may predict a therapeutic response and good prognosis, this was not supported by our findings in rhabdomyosarcoma. The tumor DNA content correlated with the clinical stage but not with the patient's clinical course or tumor histopathological type. DNA content did not appear to be as important a prognostic tool as tumor stage.

PAF and TNF increase the precursor of NF-kappa B p50 mRNA in mouse intestine: quantitative analysis by competitive PCR.

NF-kappa B, a nuclear transcription factor, is involved in the regulation of inflammatory cytokines. We have previously reported that PAF and TNF induce intestinal injury in rats and mice and the interaction of TNF and PAF probably plays a central role in its pathogenesis. In the present study, we developed a competitive PCR method to quantitate the transcripts of NF-kappa B p50/p105 gene, and investigated the effects of PAF and TNF on p50/p105 gene expression in the small intestine of C3H/HeN mice - p105 is the precursor of the p50 subunit of NF-kB. We found that NF-kappa B p50/p105 gene is constitutively expressed in the normal small intestine in small quantities (7.05 +/- 1.04 attomol/micrograms total RNA). PAF at a dose (1 microgram/kg) causing no systemic changes (e.g., hypotension, hemoconcentration), markedly increased intestinal p50/p105 transcripts within 30 min. TNF, at dose (1 mg/kg) also insufficient to induce systemic changes, increased intestinal p50/p105 gene expression, although its effect was much slower than PAF. The effect of TNF was not blocked by WEB 2086, a PAF antagonist. Our results indicate that both PAF and TNF stimulate the expression of NF-kappa B p50/p105 in vivo. However, the mechanisms of their respective actions are probably different.

Decreased phospholipase A2 activity and prostaglandin biosynthesis in Bacillus Calmette-Guérin-activated alveolar macrophages.

Alveolar macrophages from normal and BCG-infected rabbits were labelled with [14C]arachidonate and its metabolites were measured. It was found that production of both prostaglandins and 12-hydroxyeicosatetraenoic acid was diminished markedly in BCG-primed macrophages. This decrease was due partly to a depression in cyclooxygenase and lipoxygenase activity, but mainly to a decrease in arachidonic acid release, probably due to a suppression in phospholipase A2 activity. This is indicated by a consistent depression of this enzyme activity in BCG macrophage homogenates at a wide pH range, suggesting that both lysosomal an non-lysosomal phospholipases are suppressed in BCG macrophages. However, intracellular lysosomal acid phosphatase and its release were increased markedly in BCG-primed macrophages. Our previous studies have shown a close relationship between lysosomal acid hydrolase release and production of arachidonate-prostaglandins in normal macrophages. The present study shows that in activated macrophages primed by BCG, different mechanisms are operative in the control of synthesis and release of lysosomal acid hydrolases and of the phospholipase for prostaglandin production.

Hepatic angiosarcoma in childhood. A case report and review of the literature.

We describe the clinical and pathologic features of an hepatic angiosarcoma in a 5-year-old child. The neoplasm manifested as a multicentric vascular tumor and was initially treated by lobectomy. Histopathologically, the lesion showed the features of infantile hemangioendothelioma, in which foci of cytologic atypia ("type 2") were present. A recurrence with rapid growth appeared that suggested a malignant tumor, but no metastases developed. A literature review confirmed the rarity of angiosarcomas in children and underscored the difficulties of formulating a prognostic estimate about infantile hemangioendotheliomas based on histology alone. Mitotic activity and cytologic atypism are regular features of angiosarcoma in children and cannot be ignored. This report also contrasts certain features of the biology of malignant vascular tumors of the liver in childhood with the counterpart in adults.

Cellular hemangiomas ("hemangioendotheliomas") in infants. Light microscopic, immunohistochemical, and ultrastructural observations.

Cellular hemangiomas of infancy, also known as "infantile hemangioendotheliomas," are benign tumors whose dense cellularity may lead to confusion with soft tissue sarcomas. Ultrastructural and immunohistologic study revealed considerable cellular heterogeneity in these lesions despite the monomorphous appearance revealed by routine histologic preparations. Pericytes and endothelial cells are predominant, but fibroblasts and mast cells are regularly present in these tumors. An interstitially located cell of uncertain identification, expressing factor XIIIa and a macrophage marker, not previously noted, comprises an important segment of the cell population. The cell composition reflects the dynamic potential of these lesions, whose natural tendency is to grow, then to become stable, and finally to involute.

Congenital, infiltrating giant-cell angioblastoma. A new entity?

This report describes histopathologic, immunohistologic, and ultrastructural features of a locally aggressive soft-tissue tumor present since birth in an upper extremity of an infant. Because of extensive infiltration of local structures, the lesion had to be treated by amputation. The outstanding histologic feature consisted of nodular cell clusters resembling inflammatory granulomas, often with giant, multinucleated cells. On the basis of our findings, these cellular aggregates were interpreted as distorted attempts at formation of vessels. This interpretation was strengthened by the more obviously vascular structure of the tumor in many areas. A high content of stromal cells positive for factor XIIIa and histocompatability antigen (HLA)-DR was a characteristic that the tumor shared in common with angiomatoid malignant fibrous histiocytoma. However, there were also important differences that singularize the tumor described in the present study. We could find no closely comparable precedent for a lesion with these characteristics in current treatises on infantile soft-tissue tumors.

Large-cell lymphoma. Diagnostic difficulties and case study.

The present report describes the difficulties attending the establishment of a correct diagnosis in an adolescent patient with a large retroperitoneal tumor. It is known that clinical and pathologic findings may sometimes be insufficient to effect a distinction between germ-cell and lymphomatous origin of a large-celled neoplasm. Our purpose is to demonstrate that these difficulties may persist even when current methods of morphologic study, including electron microscopy, are complemented with the application of many antibodies that are commonly available for immunohistologic use. In the young, the differential diagnosis of large-celled neoplasm must include "rhabdoid" tumor, and the poorly characterized nature of this neoplasm compounds the unusually difficult diagnostic dilemma. Our problem case expressed none of many lymphoid tissue markers used, was positive for epithelial membrane antigen (EMA), and was comprised of so-called "anemone" cells visible by electron microscopy, which appearance may correspond to that of carcinomas or lymphomas. Study of gene rearrangement provided additional evidence that the neoplasm was of lymphomatous origin, by showing rearrangement of genes for immunoglobulins. This valuable technique has an important place in diagnostic surgical pathology.

Rhabdomyogenesis in renal neoplasia of childhood.

Of 220 consecutive primary renal tumors of childhood, 17 contained substantial amounts of histologically identifiable striated muscle cells (over 10% of sampled tumor parenchyma). These tumors could be further subclassified into two groups: Wilms' tumors with "massive" rhabdomyogenesis (one-third or more of the tumor parenchyma composed of muscle), and Wilms' tumors with "moderate" rhabdomyogenesis (10-30% muscle composition. The former tumors were invariably seen in young children, under 4 years of age; often the patients were infants 1 year of age, or younger, and more than half of the patients in this group had bilateral tumors. Bilaterality was not seen in patients harboring tumors with "moderate" rhabdomyogenesis, whom in addition, were older children. In both groups, there was a tendency for polypoid intrapelvic growth. All but one of the tumors described in this report were classified as Wilms' tumor; the single exception was considered be be a primary rhabdomyosarcoma of the kidney. Patients with congenital malformations related to Wilms' tumor (one aniridia, one hemihypertrophy) were seen only in the group with"massive" rhabdomyogenesis. However, anatomical lesions consistent with neoplastic multifocal origin were present in both groups. Thus, our findings indicate a definite correlation between extensive rhabdomyogenesis and clinical behavior. This relation is expressed in patterns of age distribution, bilaterality and manner of growth, which are sufficiently consistent to individualize this histologic variant as a cytodifferentiated form of nephroblastoma.

Omental-mesenteric myxoid hamartomas. Infantile lesions simulating malignant tumors.

Three infants presented with multiple nodular tumors of the omentum and mesentery characterized histologically by plump mesenchymal cells in a myxoid, well-vascularized stroma. Electron microscopy of one tumor revealed reticulated inclusions in dilated cisterna of endoplasmic reticulum. Diagnoses by the original pathologist, or by consultants from referral centers in the United States included liposarcoma, primitive sarcoma, possible leiomyosarcoma, and fibromatosis, but the subsequent evolution of the patients questions the validity of such diagnoses. Two patients received what was deemed ineffective therapy, yet survived with no evidence of disease for over a decade of close follow-up. Another patient received no therapy other than the initial surgery, and has been well for more than a year. Infantile lesions may show deceptive features of immaturity and high cellularity that are apt to be confused with a true malignancy. Omentalmesenteric "myxoid" lesions are probably hamartomatous in origin.

Hepatoblastoma. Attempt at characterization of histologic subtypes.

This is a clinicopathologic study summarizing the experience with hepatoblastomas at Children's Memorial Hospital of Chicago between 1954 and 1981. Of 21 patients studied, 13 (61.9%) died. Three major histologic epithelial patterns were identified: fetal, embryonal, and macrotrabecular. The first two may represent different stages of cytodifferentiation of hepatoblastoma cells. The macrotrabecular type had features similar to hepatocellular carcinoma of adults, from which distinction was difficult; this type pursued an aggressive clinical course. The fetal type exhibited advanced differentiation, and two cases in this category survived after surgery only; local extrahepatic dissemination was present in other cases of the fetal type. Mixed epithelial and mesenchymal tumors constituted only 23% of this series, and none contained rhabdomyoblastic elements. Although modern chemotherapy may alter the course of this disease, the small size of this series precluded definite statements in this regard. Only patients in whom the tumor was completely excised as primary treatment became long-term survivors.

Intraabdominal desmoplastic small-cell tumors with divergent differentiation. Observations on three cases of childhood.

We studied three intraabdominal tumors that manifested in childhood and were attached to peritoneum, and in which the histologic pattern suggested metastatic tumor of epithelial nature but gave no evidence of a primary neoplasm in the major abdominal organs. Follow-up observation lasted from 1 to 6 years but never disclosed a primary site. Histologic, immunohistochemical, and electronmicroscopic observations indicated a primitive malignant neoplasm of uncertain histogenesis capable of simultaneously expressing epithelial, mesenchymal, and, less consistently, neural phenotypes. In childhood, the possibility of embryonic neoplasm, such as nephroblastoma occurring in atypical sites, is difficult to exclude. Despite the prevailing uncertainty about histogenesis, combined therapy achieved an apparent cure in one of our cases.

Giant cell angioblastoma: three additional occurrences of a distinct pathologic entity.

Giant cell angioblastoma was described previously in a single case report as a congenital soft-tissue tumor with a unique morphology. In the current report, we describe three cases of giant cell angioblastoma found in three infants; one case was congenital and located in the hand, one appeared neonatally in the palate, and one on the scalp of an infant. Clinical findings and results of light microscopy, immunohistochemistry, and electron microscopy were evaluated. All tumors were ulcerated; the hand and palate tumors also infiltrated soft tissue and bone. They exhibited a solid, nodular, and plexiform proliferation of oval-to-spindle cells with a frequent striking, concentric aggregation around small vascular channels. These cells had characteristics of undifferentiated mesenchymal cells, fibroblasts, myofibroblasts, and pericytes. Co-mingled with these cells were large mononuclear and multinucleate giant cells with histiocytic features. The palatal giant cell angioblastoma, excised with positive margins, was managed with interferon-alpha and showed no progression after nearly 5 years. The hand tumor diminished in size after management with interferon-alpha, was subtotally excised, and did not progress after 27 months. Follow-up data are unavailable for the patient with the scalp lesion. Our findings validate the classification of giant cell angioblastoma as a distinct and rare entity that is locally infiltrative but slow growing. The morphology and diverse cellular differentiation are consistent with an unusual form of neoplastic angiogenesis.

Mesonephroid blastoma. A previously undescribed renal tumor of childhood.

We describe a renal tumor arising in a 4 1/2-year-old boy and characterized by the formation of epithelial tubules in a primitive mesenchymal stroma. We call attention to certain unique structural features of this tumor, which set it apart from Wilms' tumor. The tissue components regularly observed in Wilms' tumor were absent from the primary neoplasm despite exhaustive search, suggesting that this case should be considered distinct from nephroblastoma. However, a metastasis appeared that was formed entirely by undifferentiated nephrogenic cells. Based on structural appearance, histogenesis from mesonephros is tentatively proposed. No precedent was found in the literature of a tumor of this description.

Platelet-activating factor increases mucosal permeability in rat intestine via tyrosine phosphorylation of E-cadherin.

1. Platelet-activating factor (PAF), an inflammatory mediator, plays an important role in mediating intestinal injury. However, it remains unclear whether PAF has a function in the intestine. The production of PAF by normal intestine and by unstimulated intestinal epithelial cell lines suggests that PAF may have a regulatory function in the normal bowel. 2. In this study we investigated the role of PAF in modulating intestinal mucosal permeability in rats. Lumen-to-blood transit of FD-4 (dextran 4400), (an index of intestinal permeability), was assessed in sham-operated rats and rats injected with PAF (1.25 microg kg(-1), i.v., a dose insufficient to induce intestinal injury). 3. PAF-induced villus cytoskeletal changes were examined by staining the intestine for F-actin. The effect of PAF on tyrosine phosphorylation of the junctional protein E-cadherin was examined by immunoprecipitation. Some rats were pretreated with AG1288 (a tyrosine kinase inhibitor) before PAF injection, and mucosal permeability change was assessed. 4. To investigate the role of endogenous PAF upon mucosal permeability, we studied the effect of PAF antagonists on (intraluminal) glucose-induced increase in mucosal permeability. 5. We found that low dose PAF: (a) alters the cytoskeletal structure of intestinal epithelium, (b) causes the influx of FD4 from intestinal lumen to systemic circulation, (c) induces tyrosine phosphorylation of E-cadherin and cadherin-associated proteins. Glucose-induced mucosal permeability increase is abolished by using two structurally different PAF antagonists. 6. These results suggest that endogenous PAF modulates macromolecular movement across the intestinal mucosal barrier, probably via tyrosine phosphorylation of E-cadherin and cytoskeletal alteration of enterocytes.

Fibrous tumors in children - a morphologic and interphase cytogenetic analysis of problematic cases.

We describe and discuss the findings by fluorescent in situ hybridization (FISH) for detection of non-random chromosomal gains, in a group of unusual fibrous lesions in children. Nuclear disaggregation was used to prepare slides from eight cases which were hybridized using alpha-satellite enumeration probes for chromosomes 8, 11 and 17. Trisomy 8 and 11 were detected in a high percentage of nuclei in cases of congenital/infantile fibrosarcomas (ranging from 45 to 80%), and in a low grade fibrosarcoma in an older child (23%). Only gains of chromosome 17 were detected in a case of infantile fibromatosis (22%). In this study we have found that given the unconventional histopathologic features, the detection of more than one non-random chromosomal gains by FISH, may aid in further defining fibrous tumors in children, and may be useful as an ancillary diagnostic test in the future.

The human yolk sac and yolk sac carcinoma. An ultrastructural study.

The ultrastructure of the yolk sac of a 39 day old human embryo was studied. The subcellular organization was suggestive of a highly specialized absorptive function proceeding in an exocelomic-viteline direction. These findings, compatible with intense metabolic activity, are at variance with the concept of rapid involution of the yolk sac following completion of its hemopoietic and angiogenetic functions. The speculation is advanced that a potential avenue exists in the yolk sac whereby maternally derived products encounter fetal endoderm. Ultrastructural features in the normal yolk sac were compared to those existing in a tumor showing the "endodermal sinus" pattern, and reviewed in the light of the pertinent literature. These findings support the concept that attributes an endomesoblastic derivation to such neoplasms.

Mesenchymal renal tumors in infancy: a reappraisal.

Eight cases of primary mesenchymal renal tumor in infants under one year of age were studied. The patients' ages ranged from one day to seven months; all but one were diagnosed within the first three months of life. There were four typical congenital mesoblastic nephromas. Two malignant mesenchymal, one intermediate case of difficult classification designated as "cellular variant" of congenital mesoblastic nephroma, and one hemangioendothelioma. All patients were alive and free of tumor 3 9/12 to 18 10/12 years after surgery. Of the four infants with congenital mesoblastic nephroma, one was treated by tumor excision alone; nearly 13 years later this patient was free of tumor. A high degree of cellularity and a high nucleus-cytoplasm ratio were features that characterized the tumor diagnosed as "cellular variant" of congenital mesoblastic nephroma. A sarcomatous gross appearance with cavitation necrosis was seen in the two instances of malignant mesenchymal nephroma; one of these metastasized to the lung, whereas in the other, though no metastases developed, all the histologic details of the previous case were reproduced, including distinct foci of necrosis and a high mitosis rate. Mesenchymal renal tumors in young infants constitute a set more heterogeneous than has been previously assumed. They should not be considered uniformly benign. As a group, they span the whole spectrum between benign, morphologically quiescent lesions, clinically and pathologically intermediate or indeterminate ones, and outright malignant tumors with a high risk of distant spread.

Intranuclear filaments in a soft tissue sarcoma.

Intranuclear filaments aggregating into rodlike structures were found in cells of an undifferentiated soft tissue sarcoma in a child. Similar structures have been uncommonly described in human neoplasms, and uncertainties exist concerning the nature of the inclusion bearing cells in previous reports. The filaments were found to be resistant to mild trypsin digestion. Review of the pertinent literature indicates that these structures may represent the structural manifestation of a highly specialized functional state, rather than a degenerative phenomenon or an artifact. A certain selectivity of occurrence has also been noted. It is therefore plausible to speculate that intranuclear filaments may eventually constitute a morphologic criterion of interest for new tumor classifications.

Pulmonary changes following extracorporeal membrane oxygenation: autopsy study of 23 cases.

Extracorporeal membrane oxygenation (ECMO) has become an established mode of therapy in many centers for potentially fatal neonatal respiratory failure refractory to conventional therapy. We reviewed the findings of 23 autopsies of patients placed on ECMO therapy during the period from 1988 to 1992 at our institution in order to document the pulmonary histopathologic changes and to correlate such changes with the duration of treatment. Interstitial and intra-alveolar hemorrhages, as well as hyaline membrane formation, were the most common findings during the first few days of therapy. Reactive epithelial hyperplasia (bronchial and type II pneumocytes), squamous metaplasia, and smooth muscle hyperplasia were observed as early as 2 to 3 days after initiation of ECMO therapy. Interstitial fibrosis was noted only after 7 days of ECMO therapy. In three patients treated for 15, 19, and 21 days there was replacement of the terminal airways and alveoli by tall columnar and mucin-producing epithelium. Alveolar and bronchiolar calcifications were noted in seven of the 23 cases in this series. Pulmonary vascular changes were seen in association with persistent fetal circulation, meconium aspiration, and respiratory distress syndrome. These changes are most likely due to the compounded effect of ECMO and the underlying pulmonary insult.