1/3. Detection of the 20-kDa virulence-associated antigen of rhodococcus equi in malakoplakia-like lesion in pleural tissue obtained from an AIDS patient.A malakoplakia-like lesion was detected in a pleural biopsy from an AIDS patient presenting clinical and radiologic features of pneumonia. Cultures of bronchoalveolar lavage and pleural fluid evidenced rhodococcus equi as the causative agent of pleuro-pulmonary infection. Immunochemical characterization of the R. equi isolate showed the presence of a strain similar to the ATCC 33704 reference strain presenting the capsular antigen of serotype 4, and the intermediate virulence-associated antigen of 20-kDa. Histopathology of the patient's pleural biopsy showed plaques of macrophages interspersed with lymphocytes, and intracytoplasmic cocci and bacilli in macrophages, which were variably acid-fast positive. immunohistochemistry of cocci, bacilli and their degradation products resulted strongly positive when stained with a mouse monoclonal antibody (MAb) produced against the 20-kDa antigen. This finding could have important implications for the pathogenicity of R. equi for human beings, since we do not know yet all the factors involved in the formation of malakoplakia. Indeed, the results obtained in the present study, taken together with the results obtained for pigs inoculated with R. equi strains of intermediate virulence (Madarame et al. 1998), raise the possibility that most strains presenting the 20-kDa antigen may be capable of inducing malakoplakia. If this hypothesis is confirmed by immunohistochemical analysis of human pulmonary malakoplakia cases due to R. equi, the detection of this antigen may be extremely helpful in the diagnosis and treatment of such patients. This is the first report of R. equi infection in human beings that suggests a relationship between pleural malakoplakia and the virulence-associated antigen of 20-kDa.- - - - - - - - - - ranking = 1keywords = antigen (Clic here for more details about this article) |
2/3. Pleural posttransplantation lymphoproliferative disorder following liver transplantation.A case of posttransplantation lymphoproliferative disorder (PTLD) involving the pleura is reported. The patient was a 57-year-old man who underwent liver transplantation 2 years prior to the development of PTLD. The PTLD was pleural-based and was first detected by radiologic studies as a pleural effusion. Transbronchial biopsy and cytologic examination of 2 pleural fluid specimens were nondiagnostic. Subsequent open-wedge biopsy revealed a monomorphic PTLD, composed of large immunoblasts with plasmacytoid differentiation. Immunohistochemical studies demonstrated B-cell lineage with expression of monotypic cytoplasmic immunoglobulin kappa light chain and CD79a, and absence of T-cell antigens. Immunohistochemical and in situ hybridization studies demonstrated Epstein-Barr virus protein and rna, respectively. No evidence of human herpesvirus 8 dna was detected by polymerase chain reaction. We report this case because pleural-based PTLD is rare. The diagnosis of this entity is made more difficult by the fact that PTLD is often underrepresented in pleural fluid cytology samples.- - - - - - - - - - ranking = 0.1keywords = antigen (Clic here for more details about this article) |
3/3. Histoplasmoma, pleural fibrosis, and slowly enlarging pleural effusion in an asymptomatic patient.A slowly enlarging pleural effusion and significant pleural fibrosis occurred in an asymptomatic patient with a subpleural histoplasmoma. The pleural disease may be a reaction to antigen diffusing into the pleural space from the histoplasmoma. In selected patients, resection of the histoplasmoma may be necessary to prevent impairment of ventilation from pleural fibrosis.- - - - - - - - - - ranking = 0.1keywords = antigen (Clic here for more details about this article) |