Fibrin glue-antibiotic suspension in the prevention of prosthetic graft infection

The following study was done to assess whether fibrin glue-antibiotic suspension (FGAS) can prevent infection of a PTFE vascular graft in a contaminated wound. METHODS: FGAS was made by combining cryoprecipitate with a mixture of bovine thrombin, aminocaproic acid, and tobramycin (5 mg/cc thrombus). Antibiotic activity was documented by in vitro kinetics which revealed initial elutions to be greater than 8,000 mu gm/cc and elutions at 4 days to be greater than 2 mcg/cc. Twelve dogs had a 1-cm section of infrarenal aorta replaced with a PTFE graft that had been bathed in a 2-cc solution of E. coli 3 x 10(8) CFU/ml and S. aureus 3 x 10(8) CFU/ml. Both organisms were sensitive to tobramycin and cefonicid. Dogs were divided into three groups of four. Group I had a contaminated PTFE graft placed and no further therapy. Group II had a contaminated PTFE graft placed and sealed with fibrin glue. Group III had a contaminated PTFE graft placed and sealed with FGAS. All three groups received daily IV cefonicid. RESULTS: Group I: Four of four dogs were reoperated on the fourth day for suspected sepsis and all four had pseudoaneurysms (one ruptured). Three of four were culture positive for S. aureus and two of four positive for E. coli. Group II: Four of four died of anastomotic disruption by the third day. Four of four were culture positive for S. aureus and E. coli. Group III: All four dogs survived and were sacrificed on Day 17: all anastomoses were normal. Animal survival was significantly associated with the treatment given (p = 0.0025). Three of four tissue cultures of the grafts were weakly positive for S. aureus and one of four for E. coli and Pseudomonas. Serum tobramycin levels were negligible at 12, 24, 72, and 96 hours. CONCLUSIONS: The data show that FGAS was associated with a reduction in vascular graft infection and pseudoaneurysm formation after exposure to a standardized bacterial inoculum. Whether complete eradication of all organisms can be achieved with higher doses of tobramycin is as yet undetermined.     

Epithelioid trophoblastic tumor: morphological and immunohistochemical study of three lung lesions

Epithelioid trophoblastic tumor (ETT) is a term proposed for an unusual variant of trophoblastic tumor that is closely related to choriocarcinoma but shows monomorphic growth of highly atypical trophoblastic cells instead of the typical dimorphic pattern of choriocarcinoma. We report here 3 cases of ETT, all of which were lung lesions probably originating from uterine trophoblastic disease. The antecedent pregnancies of the 3 cases were hydatidiform mole, invasive mole, and term pregnancy, respectively. The tumors were composed of highly atypical mononucleate cells, which mainly involved alveolar spaces, forming nests with central eosinophilic necrosis. Multinucleate giant cells were found within the nests, but they were fewer in number than in typical choriocarcinoma. The tumors were not associated with extensive hemorrhage or necrosis, except for 1 case, in which the ETT was combined with typical dimorphic choriocarcinoma. Immunohistochemically, multinucleate giant cells and occasional mononucleate tumor cells showed positivity for human chorionic gonadotropin. Staining for human placental lactogen was positive in rare multinucleate giant cells, and in 1 case, tumor cells showed diffuse positivity for placental alkaline phosphatase. Because ETT has a remarkably epithelioid appearance in cytological and architectural features, differentiation from the epithelial malignancies is problematic. Trophoblastic markers are frequently expressed in nontrophoblastic tumors, and reactivity for those markers alone is not sufficient for exclusion of other tumors. Rather, evidence of ETT comes from a combination of morphological features, immunohistochemical study, and clinical history.     

Significance of aberrant (cytoplasmic/nuclear) expression of beta-catenin in pancreatoblastoma

This study concerns the significance of aberrant (nuclear/cytoplasmic) expression of beta-catenin in pancreatoblastoma (PBL). On immunohistochemistry, all seven PBLs examined showed nuclear/cytoplasmic expression of beta-catenin, predominantly in the squamoid corpuscles (SCs). In areas with acinar/ductular differentiation, few tumour cells displayed nuclear/cytoplasmic expression of beta-catenin and more than half of the tumour cells showed membranous expression. Two out of five (40%) tumours examined showed missense mutations in codons 33 and 37 of exon 3 of the beta-catenin gene. No mutation of the adenomatous polyposis coli (APC) gene was detected in two of the remaining three tumours. Amplifiable DNA for APC analysis was not obtained from the one other tumour. Immunoreactivity for cyclin D1, one of the nuclear targets of beta-catenin, was found predominantly in the SCs of the seven tumours. In contrast, the Ki-67 labelling index was 2-4% (median 3%) in the SCs and 8-18% (median 12%) in the other areas, indicating a negative correlation with nuclear cyclin D1 reactivity. These results imply that in PBLs, nuclear/cytoplasmic accumulation of beta-catenin and overexpression of its target gene cyclin D1 are not associated with the induction of tumour cell proliferation. Nuclear/cytoplasmic accumulation of beta-catenin may be related to the morphogenesis of the SCs that are considered most characteristic for PBL.     

Squamous cell carcinoma with cyst of the thyroid

Two cases of primary squamous cell carcinoma associated with a thyroid cyst in the thyroid are described. The majority of squamous cell carcinomas reported so far have had some degree of co-existing adenocarcinoma, while the cases presented in this report had no glandular component at all. The histogenesis of squamous cell carcinoma is not clear, but at present, it is believed that most cases arise from the follicular epithelium. In our cases, in spite of an intensive examination of serially sectioned specimens, no areas of adenocarcinoma, squamous metaplasia from the follicular epithelium, or congenital squamous remnants could be found.