Two cases of primary pulmonary artery sarcoma are reported. The patient in the first case was a 61‐year‐old male with a two‐year history of cough and exertional dyspnea, who died of intractable cardiac failure two months after admission without establishment of a diagnosis related to the etiology of cardiac failure. Autopsy revealed a sessile tumor within the pulmonary trunk and a solitary metastatic lesion in the lung. Histologic, immunohistocyto‐chemical and electron microscopic studies were performed and a diagnosis of malignant mesenchymoma was made. The patient in the second case was a 32‐year‐old male complaining of exertional dyspnea and back pain. Radiologic studies indicated a mediastinal tumor involving the pulmonary artery. Exploratory thoracotomy revealed that the mediastinal mass arose from the left pulmonary artery. He died of respiratory failure 26 months after onset of his initial symptoms. Histologic, immunocytochemical and electron microscopic studies of both surgical and autopsy materials revealed a malignant fibrous histiocytoma. One hundred ten previously reported cases of this tumor are reviewed, and its clinicopathologic and morphologic features and probable histogenesis are discussed. ACTA PATHOL JPN 38: 883∼896, 1988.

These results suggest that clusterin expression is induced in pancreatic cancer as well as chronic pancreatitis and that downregulation of clusterin may be involved in the progression of pancreatic cancer.

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A retrospective analysis of 183 papillary thyroid carcinomas was made in order to assess the prognostic factors related to survival. The following factors were found to adversely affect the prognosis: trabecular subtype of papillary carcinoma, the extent of the primary tumour, regional lymph node involvement, the presence of distant metastases, old age, male sex and the extent of the neck dissection. The presence of the follicular variant of papillary carcinoma and the extent of the thyroidectomy did not influence the prognosis. The trabecular subtype of papillary carcinoma is characterized by a trabecular or solid arrangement of follicular cells with nuclei of ground-glass appearance. Univariate and multivariate analysis indicated that patients with this type of thyroid tumour had a poorer prognosis than those with the well-differentiated or follicular variants of papillary carcinoma. In our opinion the trabecular subtype of papillary carcinoma should be included as a separate entity in the WHO classification of thyroid tumours.

The p21 protein product of the cellular oncogene ras, designated ras p21, has been detected immunohistochemically in normal, benign and malignant human thyroid tissues. With the monoclonal antibody RAP-5 generated against a synthetic peptide corresponding to amino acid positions 10 to 17 of the ras p21 protein and an avidin-biotin-peroxidase complex (ABC), the expression of the ras p21 was evaluated in paraffin-embedded sections. Western blot analysis using fresh thyroid carcinoma tissue revealed double protein bands, one band was at molecular weight 21,000 and the other was a more rapidly migrating band at the molecular weight 17,500. Immunohistochemically, papillary adenocarcinomas of the thyroid showed moderate to intense stainings for ras p21 in most cases. Cytoplasmic and apical surface stainings were the most common patterns of immunoreactivity. Adenomas showed variable ras p21 positivity in cytoplasm and apical surface stainings of adenomas were negative to borderline in most cases. The cytoplasm of tissues of Hashimoto's thyroiditis, Graves' disease, and normal thyroid tissues was uniformly ras p21 positive, but the apical cell surface was nonreactive for ras p21 in all tissues. Judging from the findings obtained on this large series of normal, benign, and malignant thyroid tissues, the elevation of ras p21 may be a common event in thyroid neoplasm, and especially elevated ras expression in the apical cell surface may be characteristic to papillary carcinomas of the thyroid. This suggests that apical surface expression of ras p21 may be important in the development of thyroid carcinomas and be useful in differentiation of papillary adenocarcinoma.