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Constitutively activating mutations in the TSH receptor (TSHR) gene and in the Gs alpha gene are frequent molecular causes for solitary toxic nodules of the thyroid. However, the etiology of toxic multinodular goiter is still largely unknown. Therefore, DNA from nodular and quiescent surrounding tissue of six patients with toxic multinodular goiters was screened for mutations in exons 9 and 10 of the TSHR gene and exons 7-10 of the Gs alpha gene by direct automated sequencing. In one patient, two different somatic TSHR mutations were identified in two different toxic nodules (L632I and F631L). In another patient, two different toxic nodules harbored the same TSHR mutation (I630L), whereas only one TSHR mutation (F631L) was identified in one of the two toxic nodules of an additional patient. In the other three patients, no mutations could be found in exons 9 and 10 of the TSHR gene or in exons 7-10 of the Gs alpha gene. Our results demonstrate that not only solitary toxic adenomas but also toxic multinodular goiters can be caused by constitutively activating mutations of the TSHR. In addition to mutations in the TSHR and possibly in Gs alpha, there are probably other still unknown mechanisms that cause hot nodules in toxic multinodular goiters.

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The aetiopathogenesis of autoimmune thyroid disease is still a matter for discussion. Morphologically, these illnesses are associated with a broad spectrum of overlapping changes. Thus, pathology cannot serve as the logical basis for a new classification. Therefore this overview makes use of the conventional nomenclature of clinically established entities and includes recently defined lesions. Besides histological characteristics, details of differential diagnostic value are presented in the context of clinical and laboratory data relevant for pathological classification.

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Mutant-enriched PCR was applied to the detection of mutations at codons 12 and 13 of K-ras genes in the stools of patients with colorectal cancer. Mutations were analyzed in stool samples obtained prior to surgery. Resected tumor specimens were screened for K-ras mutations by PCR-mediated RFLP analysis. Using normal stool samples, assay conditions were adjusted to optimal sensitivity and specificity. The following specimens were included in the study: 16 stool samples corresponding to carcinomas in which K-ras mutations had been identified; 7 randomly selected stool samples corresponding to carcinomas which were negative for K-ras mutations; 1 stool sample from a patient with non-Hodgkin's lymphoma. In 13 of the 16 stool samples (81%) corresponding to tumors in which K-ras mutations had been identified previously, K-ras mutations were detected. In 2 of the 7 stool samples corresponding to tumors in which K-ras mutations had not been detected by previous PCR-mediated RFLP analysis, K-ras mutations were also present. Reanalyses of the tumors corresponding to these 2 positive stool samples by mutant-enriched PCR revealed a K-ras mutation in one of the tumors. The stool and tumor of the patient with non-Hodgkins lymphoma were negative for K-ras mutations. DNA sequence analysis revealed that, for each of the K-ras mutations identified in stool samples, identical base substitutions were present in the corresponding tumor tissue. The results indicate that tumor cells harboring K-ras mutations can be detected in the stools of patients with colorectal cancer by mutant-enriched PCR with high sensitivity and specificity. Because of the simplicity of the technique, it may be suitable for screening of stool samples for mutations of the K-ras gene.

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The aetiopathogenesis of autoimmune thyroid diseases is the subject of various partly contradicting hypotheses and theories. Morphologically, these illnesses are associated with a broad spectrum of overlapping changes. Thus, pathology either can not serve as the logical basis for a new classification of autoimmune thyroid diseases. This overview therefore makes use of the conventional nomenclature of clinically established entities and includes recently defined lesions. Besides histological characteristics details of differential diagnostic value are presented in the context of clinical and laboratory data relevant for pathological typing.

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The present study was initiated to characterize thyrotropin receptor (TSH-R) expression in thyroids from patients with Graves' disease, as well as parameters that influence TSH-R expression either causally, such as interferon-gamma (IFN-gamma), the leading candidate among the cytokines thought to play a key role in the initiation of autoimmune thyroid disease, or therapeutically, such as iodide, which is used to prepare patients for surgery. Our data show that there is an average 4-fold increase of TSH-R mRNA levels in the thyroids of Graves' patients coming to surgery, which is paralleled by an increase in TSH-R protein levels and TSH binding capacity. The increase does not appear to be related to IFN-gamma since IFN-gamma transcripts are barely detectable in most Graves' patients. Iodide treatment causes a 2-fold decrease in TSH-R expression in association with significant decreases in major histocompatibility complex (MHC) class I and class II gene expression. These last data are compatible with a recently enunciated "transcription factor hypothesis" according to which abnormally high TSH-R and MHC class I and class II gene expression in Graves' thyroids are the result of a loss of the normal negative regulation of these genes necessary to allow the normal growth and function of the gland, yet preserve self-tolerance.

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An example of a benign haemorrhagic spindle cell tumour of the lymph node (synonym: intranodal myofibroblastoma) is presented, which was first described 5 years ago and has not as yet been documented in the German literature. This rare benign mesenchymal neoplasm of the lymph node occurs almost exclusively in the inguinal region. Diagnostic criteria include its composition of myofibroblastic cells (with immunoreactivity for vimentin and actin), which may show nuclear palisading, the presence of peripheral haemorrhage zones and the occurrence of characteristic amianthoid structures, which have the ultrastructural appearance of dense meshworks of collagen fibers. Knowledge of this tumour entity is important for differential diagnosis of primary and secondary malignant mesenchymal neoplasias of the lymph node.

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In 15 piglets with anorectal malformations (high and low anomalies) we performed angiographies of the pelvic arterial system. 3 healthy animals were used as control group. None of the animals had isolated rectal atresia which is assumed to be due to vascular disorders. In all animals we could demonstrate normal superior and inferior rectal arteries. Thus our results support the hypothesis that anorectal malformations, with the exception of isolated rectal atresia, are not associated with vascular malperfusion during embryogenesis.

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A 10-year-old girl was operated because of an epidermoid cyst of the spleen weighing 2 kilograms. The cyst was enucleated and the spleen reconstructed. This procedure is seen as the operation of choice as the development of post-splenectomy sepsis can thus be prevented.

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A 12-year old boy with mucoviscidosis developed a mechanical obstruction of the small intestine. The diagnosis of a meconium ileus equivalent was made and a conservative treatment was started. After this treatment failed, a laparotomy was performed which verified the diagnosis of a meconium ileus equivalent. It was possible to move the inspissated feces inside the terminal ileum into the ascending colon. The postoperative course was uneventful. The etiology, differential diagnosis, and both conservative and operative treatment of this complication of the mucoviscidosis are discussed.

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