CALCOFLUOR WHITE STAIN FOR THE DETECTION OF PNEUMOCYSTIS-CARINII IN TRANSBRONCHIAL LUNG-BIOPSY SPECIMENS - A STUDY OF 68 CASES

Calcofluor white (CFW), a chemofluorescent agent, has proven effective in the recognition of Pneumocystis carinii cysts in respiratory fluid s and secretions. However, its usefulness in the recognition of P. car inii cysts in tissue preparations has not been established. We studied 68 formalin-fixed, paraffin-embedded, transbronchial tissue biopsy sp ecimens from individuals seropositive for the human immunodeficiency v irus and stained them with the CFW stain and the conventional Gomori m ethenamine silver (GMS) stain to determine the concordance rate of the two stains, CFW-positive specimens showed light peripheral staining a nd a unique double parenthesis-like structure near the center of the c ysts, Thirty-six (52.9%) of the 68 specimens were CFW and GMS positive , whereas 27 (39.7%) of the specimens were negative by both techniques , yielding a concordance rate of 92.6%, Five (7.4%) of the 68 specimen s showed disparate results, and, of these, four (5.9%) were CFW positi ve and GMS negative, whereas one (1.5%) was CFW negative and GMS posit ive. We conclude that the CFW stain is suitable and useful for the dem onstration of P. carinii cysts in tissue preparations.