A Monte Carlo simulation model for radiation dose to metastatic skeletal tumor from rhenium-186(Sn)-HEDP.

UNLABELLED: A Monte Carlo model has been developed for simulation of dose delivery to skeletal metastases by the bone surface-seeking radiopharmaceutical 186Re (Sn)-HEDP. METHODS: The model simulates: (1) the heterogeneous small scale geometry of the soft tissue/bone-spicule structure in the lesions as determined by histomorphometric measurements of histologic specimens, (2) the small scale spatial distribution of the radiopharmaceutical on the lesion bone spicule surface as determined by autoradiography, and (3) the 186Re beta and conversion electron decay spectrum and the associated charged particle transport within the modeled geometries. The results are compared with the commonly employed uniform lesion model, which assumes: (1) homogeneous lesion morphology, (2) uniform distribution of radioactivity within the lesion, and (3) complete energy deposition by charged particles within the lesion due to decay of this activity. Gamma and x-ray photons from the 186Re spectrum were assumed to escape from the lesion volume in both models. RESULTS: Results show a significant dependence on the bone volume fraction and hence on the histology of the lesion (lytic, blastic or mixed). The uniform lesion model calculations underestimate the radiation dose to blastic lesions by as much as a factor of 1.8. However, for lytic lesions with low bone volume fractions, both models provide similar dose values. CONCLUSIONS: These new model calculations provide a mechanism for optimizing treatment planning and dose response evaluations of therapeutic bone-seeking radiopharmaceuticals.

Comparison of two methods for same-day identification of Enterobacteriaceae.

Two commercial methods, API 20E (as modified for same-day enterobacterial identification) and Micro-ID, were evaluated for ability to provide useful same-day information of 368 clinically isolated Enterobacteriaceae. Organisms included Escherichia coli (54), Shigella (7), Edwardsiella tarda (1), Salmonella enteritidis (10), Citrobacter (30), Klebsiella (55), Enterobacter (68), Hafnia alvei (2), Serratia (33), Proteus (64), Morganella morganii (24), Providencia (18), and Yersinia enterocolitica (2). Methods were those of manufacturers without supplemental tests. API at five hours identified 78.5% of strains to species, 9.5% to genus only, 10.1% as part of a spectrum of identifications (SI), and 1.9% incorrect. Micro-ID at four hours yielded 90.0% correct identification to species and 3.3% to genus only, 4.0% SI, and 2.7% incorrect. API identification of many Serratia, Citrobacter, Providencia strains was to genus only; most incorrect results occurred in Serratia marcescens. Micro-ID identified most organisms to species; incorrect identifications were mainly S. marcescens and Klebsiella pneumoniae. Both systems provided excellent identification of E. coli. Both methods sacrifice a degree of accuracy that varies with the species tested, as compared to overnight systems, but both provide rapid information of potential clinical value.

Cutaneous manifestations of strongyloidiasis.

Strongyloides stercoralis is a small intestinal nematode that has the ability to multiply within the human host. Because of the potential opportunistic behavior of this parasite, immunocompromised patients may develop fatal disseminated infections. Chronic strongyloidiasis may last decades and give rise to various dermatologic lesions, the most characteristic of which is larva currens, a serpiginous creeping urticarial eruption caused by the intradermal migration of the infective filariform larvae. Rarely recognized is the presence of widespread petechiae and purpura that may develop in patients with disseminated infections. A 64-year-old immunosuppressed man developed fatal extraintestinal S stercoralis infection with extensive purpura associated with massive invasion of the skin by migrating larvae.

Complement and antibody deposition in Brazilian pemphigus foliaceus and correlation of disease activity with circulating antibodies.

Brazilian pemphigus foliaceus is a blistering skin disease endemic to central and southern areas of South America. In this study of skin biopsy specimens from 14 patients we present evidence that complement and immunoglobulins were present by direct immunofluorescence in the epidermal intercellular spaces in all patients. Eight of 14 patients had granular deposits of C3 in the basement membrane zone. By indirect immunofluorescence, serum samples from all 19 patients tested demonstrated the presence of circulating IgG autoantibody. Autoantibodies deposited in the intercellular spaces in titers ranging from 1:10 to more than 1:1280, and the titers drastically decreased during treatment. This is the first study to demonstrate complement deposition in the skin in Brazilian pemphigus foliaceus.

Primary malignant mesenchymoma of bone.

Primary malignant mesenchymoma of bone is a rare neoplasm consisting of two or more unrelated tissue elements other than a fibrosarcomatous component. To our knowledge, only six cases have been reported in the literature. A case of malignant mesenchymoma composed of rhabdomyosarcoma, chondrosarcoma, and osteosarcoma arising within the right acetabulum, resulting in the patient's death 4 months after presentation, is reported, and the literature is reviewed, with a discussion of the similarities to dedifferentiated chondrosarcoma.

Lipedematous alopecia.

Lipedematous alopecia is an unusual disorder characterized by short, brittle scalp hairs associated with thickening of the scalp by adipose tissue. All except one reported case have been in African-American females. It is our purpose to report the seventh case of this condition.

Malignant mixed tumor of the gallbladder: report of two cases and a review of the literature.

Two cases of malignant mixed tumor of the gallbladder are reported. The histology of both revealed malignant mesenchymal elements (chondroid, osteoid, fibrous) admixed with adenocarcinoma. One patients had widespread disease and died three days following diagnosis. The second patient had tumor limited to the gallbladder and is alive with no evidence of disease 31 months following cholecystectomy. Only three other such tumors are reported in the English literature. Analysis of these cases indicates that the behavior and etiology of malignant mixed tumors may be similar to that of carcinomas of the gallbladder.

Transection of radial digital nerve of the thumb during trigger release.

Iatrogenic laceration of the radial digital nerve of the thumb during trigger release occurred in four patients. Histologic cross sections through the thumb in cadaveric specimens at the level of the metacarpophalangeal crease showed the radial digital nerve to be 2.19 mm beneath the dermis and 1.15 mm directly anterior to the radial sesamoid bone. In this position the nerve is vulnerable to transection when it is trapped between the sesamoid and the knife blade.

Four methods for identification of gram-negative nonfermenting rods: organisms more commonly encountered in clinical specimens.

Four commercial kits, Oxi/Ferm (OF), API 20E (AP), Minitek (MT; BBL Microbiology Systems), and Flow N/F (NF), were evaluated, without additional tests, for identification of 258 gram-negative nonfermentative rods. OF and MT were read after 48 h of incubation, and AP and NF were read after both 24 and 48 h of incubation, respectively. Overall, OF correctly identified 51% of strains, with 46% as part (but not first) of a spectrum of identifications (SI), and 3% incorrect species identification. MT yielded 85% correct identification, with 15% SI. Of 126 glucose-positive strains, or those with greater than or equal to 3 positive AP reactions after 24 h, 60% were correctly identified, with 40% SI; incubation for an additional 24 h raised the rate of correct identification to 99%, with 1% SI. A total of 132 strains yield less than 3 positive AP reactions after 24 h and were identified after 48 h only; of these, 82% were correctly identified, with 17% SI and 1% incorrect species identification. NF correctly identified 79% of cultures after 24 h, with 21% SI; corresponding figures after an additional 24 h of incubation were 80% and 20%, respectively. All four commercial methods show promise; OF is easiest to inoculate, but requires extra tests for optimal identification. AP reliably identifies the majority of clinically important nonfermenters, with fairly good species identification of saccharolytic strains after 24 h. MT yields reliable identification of most nonfermenters and has the advantage of flexibility. NF is easy to inoculate, yields satisfactory identification rates, and may be read after 24 h of incubation.

Comparison of four methods for identification of gram-negative non-fermenters: organisms less commonly encountered in clinical specimens.

Four commercial kits--Oxi/Ferm (OF), API 20E (AP), Minitek (MT), Flow N/F (NF) were evaluated, without additional tests, for identification of 105 opportunistic Gram-negative non-fermentative rods. Of correctly identified 42% of strains, with 35% as part (but not first) of a spectrum of identifications (SI) and 23% incorrect identification. MT yielded 75% correct identification, with 12% SI and 13% incorrect. AP correctly identified 64% of strains, with 26% SI, 10% incorrect. NF correctly speciated 70% of strains, with 24% SI, 6% incorrect. All 4 methods show deficiencies in identification of these rare but increasingly clinically encountered organisms. Addition of new tests/modification of existing ones would render these systems more capable of identifying this organisms group.

Comparison of three methods for identification of Enterobacteriaceae.

This study compares the ability of three commercial overnight methods, API 20E, Minitek and Enteric-Tek, to accurately and completely identify 368 clinically isolated Enterobacteriaceae without supplemental tests. Organisms included Escherichia coli (54 strains), Shigella spp. (7), Edwardsiella tarda (1), Salmonella enteritidis (10), Citrobacter spp. (30), Klebsiella spp. (55), Enterobacter spp. (68), Hafnia alvei (2), Serratia spp. (33), Proteus spp. (64), Morganella morganii (24), Providencia spp. (18), and Yersinia enterocolitica (2). Methods were those of the manufactures without supplemental tests. API 20E correctly identified 93.2% of strains to species and 3.3% to genus level only, with 3.0% as part of a spectrum of identifications, and 0.5% incorrect identifications. Minitek yielded 96.0% correct identifications to species and 0.5% to genus level only, with 2.5% spectrum identifications, and 1.0% incorrect identifications. Enteric-Tek correctly identified 97.0% of strains to species level with 3.0% spectrum identifications. API 20E identification of some Serratia and Citrobacter strains was to genus level only. Problem organisms for Minitek included Enterobacter agglomerans and Serratia marcescens. A comparison of these three commercial methods shows that all three have the ability to identify most clinically isolated Enterobacteriaceae without supplemental tests.