Malignant tumors of childhood

In the past 20 years, cancer in the age group, 0-14 years has become the second leading cause of death by disease. At some ages, notably between 5 and 14, it may be the leading cause of death by disease. Leukemia is the most frequent form of cancer in childhood, and tumors of the brain are in second place. An attempt should be made to categorize more accurately tumors stated in reports as "miscellaneous," since in the reports analyzed herein, 15.8 per cent of all malignant lesions were so classified.     

Image processing of thymus tumors]

Altogether 40 thymic tumor patients were investigated. Radiograms and pneumomediastinograms were subjected to processing aposteriori (increased contrast and spatial filtration). Spatial filtration improved selective analysis of spatial frequencies of imaging. Processing of images specified diagnosis of thymomas by underlining the shapes of normal and abnormal mediastinal formations and signs of invasion of the pericardium and pleura.     

Diagnostic potentials of computed tomography in tumors of the thymus

115 patients with different morphological thymus lesions, including 67 with thymoma have been examined on a computer tomograph "Somatom DR-2" ("Siemens", FRG). Characteristic features of hyperplasia and thymus cysts, as well as benign and malignant thymus tumours have been revealed by computer tomography (CT). Diagnostic value of CT in conditions of pneumomediastinum and CT employing an "amplification" technique in dynamic CT-scanning (angio-CT) in combination with puncture tumour biopsy under CT control are discussed. CT was found to have certain advantages over other diagnostic techniques: simplicity, safety, the value of the information obtained, possible shortening of the diagnostic period.     

Malignant tumors of the stomach: apropos of 583 anatomo-clinical cases

A retrospective study interesting 582 anatomoclinical cases of gastric malignant tumors was realised in two anatomo-pathological services of Tunis from 1970 to 1985. The average age of patients is 55 years old, with extensive ranges from 17 to 85 years old. The authors point out significative male predominance 64.6% of cases. The ulcered form is the most frequent, about 3.8% of macroscopic aspect cases. Among these last, the authors find 26.7% of ulcerating and polypoid form with invasive characteristics, and 18.83% of linitis plastica. The pyloric area localisation is the most frequent, 68% of cases. Diffuse tumors are observed in 8.47% of cases and numerous stomach localisation in 0.82% of cases. 84% of histological aspect are represented by adenocarcinoma, the most frequent of them (35%) is well differentiated type, then the poorly differentiated (20%) and atypic form (19.75%). Frequency of lymphosarcoma reaches 14.7%, the first is the centroblastic form, then lymphoblastic and lymphoplasmocytic forms. Concerning evolution, gastric cancer is an infiltrative tumor: serosal surface is attempted in 69.5% of cases, and during the first chirurgical act half cases show lymph nodes metastasis.     

Effects of thymus grafts in nude mice transplated with human malignant tumors

The effect of neonatal thymus grafts implanted in nude mice previously transplanted with three different human malignant tumors - an adenocarcinoma of the colon, a malignant melanoma and a Burkitt's lymphoma - were studied. In all immunologically reconstituted animals tumord were rejected. Tumor rejection stated 2-3 weeks after thymus implantation, and was completed after 30-6 weeks. Histological examination of lymphoid tissues showed a correlation between immunological reconstitution and tumor rejection. The rejection process showed a characteristic histologic picture with 3 phases - an early, an intermediate and a late phase - these were similar in the three tumor types examined. The possible mechanisms of reconstitution and tumor rejection are discussed.     

Malignant transformation in concurrent benign mixed tumors of the parotid and submaxillary glands

This patient is the only reported case of concomitant mixed tumors of the parotid and contralateral submaxillary gland. Each lesion had histologic changes consistent with different stages in the transformation of a benign to a malignant mixed tumor. Identifying premalignant disease in the parotid tumor and early preinvasive carcinoma in the submaxillary tumor lends support to the concept of malignant progression in salivary gland mixed tumors.     

Characterization of lymphoid tumors induced by a recombinant murine retrovirus carrying the avian v-myc oncogene. Identification of novel (B-lymphoid) tumors in the thymus

Lymphoid tumors induced by a recombinant murine retrovirus carrying the v-myc oncogene of avian MC29 virus were characterized. The Moloney murine leukemia virus myc oncogene (M-MuLV (myc], carried by an amphotropic MuLV helper, induced tumors in NIH Swiss and NFS/N mice after a relatively long latency (8 to 24 wk). Tumor masses appeared in the thymus, spleen, and lymph nodes. Flow cytometry of the tumor cells indicated that approximately 50% were positive for Thy 1.2. Most of these tumors also expressed one or more other cell surface markers of thymocytes and mature T cells (CD4, CD8). Southern blot hybridization revealed genomic rearrangements for the TCR beta genes. The TCR beta analysis suggested that the M-MuLV(myc)-induced Thy 1.2+ tumors were derived from somewhat less mature cells than tumors induced by M-MuLV, which is a classical non-acute retrovirus lacking an oncogene. The remainder of the M-MuLV(myc)-induced tumors were Thy 1.2-, but they were positive for Ly-5 (B220) and also for MAC-2. The Thy 1.2- tumors were characteristically located in the thymus. However, they were negative for TCR beta gene rearrangements. Some, but not all, of the Thy 1.2- tumors contained rearrangements for Ig genes. Additionally, they typically expressed mRNA specific for B but not for T cells. Thus, these thymic tumors had characteristics of the B cell lineage. Tumor transplantation experiments demonstrated that the Thy 1.2- tumor cells could reestablish in the thymus and spleen of irradiated hosts, and low level expression of the Thy 1 molecule was observed in the thymus but not the spleen on the first passage. After serial passage, one Thy 1- tumor altered its cell surface phenotype to Thy 1low B220-.     

Neuroendocrinology of the thymus

The neuropeptides oxytocin (OT) and vasopressin (VP) are synthesized in the human thymus in a similar way as in the hypothalamo-neurophypophyseal system. Immunocytochemistry with polyclonal and monoclonal antibodies revealed that immunoreactive OT- and VP-producing cells are localized in the subcapsular cortex and medulla of human and murine thymuses. The epithelial nature of the neuroendocrine thymic cells is demonstrated by their immunostaining with a monoclonal antibody against cytokeratin. An original example of a neuroendocrine-immune microenvironment is given by the thymic nurse cells which are composed of a large neuroendocrine epithelial cell enclosing numerous mitotic immature thymocytes. These observations and the previously reported mitogenic and immunomodulatory properties of VP and OT upon mature T cells and thymocytes strongly support the existence of a neuroendocrine thymo-lymphoid axis and an active role of thymic VP and OT in T cell differentiation and activation.     

Binding of alcian blue by the outer perimembrane layers of cells in the liver, thymus and transplantable tumors

Dye sorption did not change the electrophoretic mobility of cells obtained from the liver, thymus and solid tumors, but reduced such a mobility in ascite tumor cells. The reduction of the electrical charge of ascite tumor cells was conditioned by the binding of dye with hyaluronic and sialic acids.     

Malignant tumors during the first 2 decades of life in the offspring of atomic bomb survivors.

The risk of cancer (incidence) prior to age 20 years has been determined for children born to atomic bomb survivors and to a suitable comparison group. Tumor ascertainment was through death certificates and the tumor registries maintained in Hiroshima and Nagasaki. The rationale for the study stemmed from the evidence that a significant proportion of such childhood tumors as retinoblastoma and Wilms tumor arise on the basis of a mutant gene inherited from one parent plus a second somatic cell mutation involving the allele of this gene. Gonadal radiation doses were calculated by the recently established DS86 system, supplemented by an ad hoc system for those children for one or both of whose parents a DS86 dose could not be computed but for whom an ad hoc dose could be developed on the basis of the available information. The total data set consisted of (1) a cohort of 31,150 live-born children one or both of whose parents received greater than 0.01 Sv of radiation at the time of the atomic bombings (average conjoint gonad exposure 0.43 Sv) and (2) two suitable comparison groups totaling 41,066 children. Altogether, 43 malignant tumors were ascertained in the children of exposed parents, and 49 malignant tumors were ascertained in the two control groups. A multiple linear regression analysis revealed no increase in malignancy in the children of exposed parents. However, examination of the data suggested that only 3.0-5.0% of the tumors of childhood that were observed in the comparison groups are associated with an inherited genetic predisposition that would be expected to exhibit an altered frequency if the parental mutation rate were increased. There is thus far no confirmation of the positive findings that Nomura found in a mouse system.     

Malignant mesenchymal tumors in two white-tailed jack rabbits (Lepus townsendii)

Two white-tailed jack rabbits (Lepus townsendii) with proliferative lesions in their internal organs were submitted to the Canadian Cooperative Wildlife Health Centre (Saskatoon, Saskatchewan, Canada) for necropsy because of concern that dogs that had contact with the hares might have been exposed to an infectious disease. In both hares, the primary diagnosis was neoplasia. One hare had metastatic leiomyosarcoma and uterine fibroma, the other had metastatic mesenchymal tumors involving the liver and mesentery. These cases represent the only reports of malignant mesenchymal tumors in white-tailed jack rabbits that we have found in the literature.