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A case of malignant thymoma is presented. The electron microscopic (EM) findings of the lymphocyte—epithelial relationships were similar to these previously described. Utilizing specific monoclonal antibodies to differentiate thymocytes from T-lymphocytes, the small cell population with ultrastructural features of lymphoid cells consisted of true thymocytes rather than peripheral T-lymphocytes. The latter finding may prove to be of importance in differentiating thymomas from reactive or most neoplastic lymphocytic processes involving the thymus gland.

The clinicopathologic and ultrastructural features of a sarcomatoid carcinoma of the pancreas presenting initially as gastric carcinoma are described. By light microscopy, the tumor contained cellular patterns similar to those present in tumors of mesenchymal origin. Spindle cell areas arranged in a storiform pattern were present. Ultrastructurally, bundles of cytoplasmic microfilaments were present in the cell cytoplasm and were similar in distribution to those found on fine structural examination in tumors of mesenchymal origin. Rows of desmosomes were found between cells supporting an epithelial origin for this tumor. Following initial therapy, metastatic tumor produced polypoid lesions in the small intestine resulting in recurrent small bowel intussuceptions. Our findings indicate that sarcomatoid carcinoma of the pancreas, by both light and ultrastructural examination, is a heterogenous tumor at the cellular level and may be a cause of repeated intussuception when intraluminal compromise occurs.

Small cell carcinoma of the cervix is a term used to describe several entities including cervical carcinoid, "oat cell" carcinoma, reserve cell carcinoma, and poorly differentiated nonkeratinizing squamous cell carcinoma. The light microscopic, ultrastructural, and clinical features of seven small cell cervical carcinomas are presented in this report. Five tumors in our report were diagnosed as small cell anaplastic or oat cell carcinoma by light microscopy. This diagnosis was associated with a poor prognosis, and four of these patients were dead of disease within 24 months. The ultrastructural features of these tumors were similar, but neurosecretory granules were demonstrable in only three of the five cases. Evidence of glandular differentiation was present in one of the five cases, and dual differentiation, i.e., neuroendocrine and squamous, was noted in another. The similarities between pulmonary small cell carcinoma and these cervical lesions are discussed and the literature is reviewed. Also included in the study is a well-differentiated neuroendocrine lesion, a carcinoid that behaved in an aggressive fashion. The final case was a carcinoma putatively derived from reserve cells. The features that help make the diagnosis of reserve cell carcinoma and that distinguish this lesion from other small cell carcinomas are presented.

The development of coronary atherosclerosis in response to acute intimal injury and severe hypercholesterolemia was studied in 18 swine, nine normal and nine with von Willebrand's disease, an inherited disorder affecting platelet-vessel wall interactions. The left anterior descending coronary artery was denuded of endothelium by balloon catheterization, while the circumflex and right coronary arteries served as nonballooned controls. All swine were maintained on a 2% cholesterol diet for 4 months. The extent of atherosclerotic involvement was evaluated from four indices: percent intimal area, percent luminal narrowing, ratio of intimal to medial area, and luminal form. No differences in coronary atherosclerosis were observed between phenotypes in either ballooned or nonballooned vessels, nor were there any differences between ballooned and nonballooned vessels within either phenotype (p greater than 0.05). The major variable affecting coronary atherosclerosis was serum cholesterol. There was a significant positive relationship between serum cholesterol concentration and the extent of intimal lesions (r = 0.62, p = 0.006) that was independent of plasma von Willebrand factor concentration. These findings suggest that severe hypercholesterolemia promotes the development of porcine coronary atherosclerosis through a mechanism(s) that is independent of acute intimal injury or von Willebrand factor-mediated platelet response to injury.

An 82-year-old man presented with a right breast mass. Histologic examination of an excisional biopsy showed lobular in situ and infiltrating carcinoma. The patient was phenotypically male and had fathered children. There was no history of predisposing factors to breast lesions, such as drug use or gynecomastia. In our review, this is the first case of lobular in situ and infiltrating carcinoma of the male breast in a phenotypic and apparently genotypic male.

Pancreatic neoplasms are common and a leading cause of death from malignant disease. Their aggressiveness as well as the poor results of treatment has led to a somewhat nihilistic attitude in their surgical management with an emphasis on palliation rather than cure. Papillary cystic neoplasm of the pancreas, although rare, is frequently confused with more malignant tumors which are less successfully treated by pancreatic resection. This neoplasm arises from ductular epithelium, usually occurs in young women, and often remains asymptomatic until it becomes manifest as an abdominal mass or by a complication, e.g., rupture, hemorrhage, or secondary infection. Because of lack of familiarity with the tumor as well as its unusual presentation, the diagnosis is infrequently made at the initial operation. Our experience with 3 young females with papillary cystic neoplasms of the pancreas is reported. Included is a review of the literature indicating the unique characteristics of the tumor. Although locally invasive, these tumors appear to have limited malignant potential and rarely metastasize. An aggressive surgical approach seems fully justified.

• We describe the second reported case of cutaneous infarction as a manifestation of disseminated mucormycosis. The lesion, which closely resembled ecthyma gangrenosum, occurred in a leukemic patient who was on a regimen of broad-spectrum antibiotics. In this case as in the only other reported case,Mucor pusilluswas the cause. (Arch Dermatol113:1075-1076, 1977)

BLOOD contains a proenzyme, plasminogen (profibrinolysin), which is converted to the proteolytic enzyme plasmin (fibrinolysin) by plasminogen activator. The level of plasminogen activator in the blood is increased in conditions of stress and after injection of epinephrine or nicotinic acid1,2. The origin of blood plasminogen activator has not been established with certainty although it has been suggested that it may be derived from the plasminogen activator activity found in association with the endothelial lining of vessel walls3–5. In dogs, blood fibrinolytic activity can be increased by intravenous injection of a number of vasoactive drugs6,7, but vasodilative drugs (for example, histamine) appear to be more effective than vasoconstrictive ones8.

IT has been known for many years that patients with classic haemophilia bleed because they lack a plasma factor required for normal blood coagulation. This factor, factor VIII (antihaemophilic factor) of normal plasma, has been extensively investigated, but its exact site of origin is unknown. Recent developments in organ transplantation have stimulated us to look for the specific organ source of this procoagulant. If the site of synthesis of factor VIII could be identified, permanent replacement of the deficient factor in haemophilia might be possible. In the past, a variety of experimental approaches has been used to investigate the body's mechanisms for maintaining haemostatic levels of factor VIII: organ ablation1, total body irradiation2, administration of hepatotoxins3,4, reticulo-endothelial blockade5, physical exercise6, hormone administration7, and thromboplastin injections4. Several recent investigations have suggested that the spleen may play a part in the regulation of concentrations of factor VIII in the plasma of normal individuals. Weaver et al. demonstrated that factor VIII is maintained at normal concentrations when intact normal dogs are crosscirculated with haemophilic dogs, but that the concentrations decrease if a splenectomy is first performed on the normal animals8. In humans, Libre et al.9 have observed that splenectomy abolishes the rise in factor VIII that is known to follow injection of adrenaline into normal subjects10. Pool was able to recover antihaemophilic activity in extracts of splenic tissue, but not from a variety of other tissues11.