Herpetic tracheobronchitis detected at bronchoscopy: cytologic diagnosis by the immunoperoxidase method

Herpes simplex virus (HSV) infection of the respiratory tract requires rapid specific diagnosis to avoid late complications and maximize the efficacy of available drug therapy. We report a method of accomplishing this that was tested in 33 cytologic specimens derived from sputum, washings, or brushings from 25 debilitated elderly males suffering from a variety of underlying neoplastic and nonneoplastic chronic diseases. All specimens had shown either single cells (54%), multinucleated groups (8%), or both (38%); they displayed the ground-glass appearance (86%), discrete nuclear inclusions (4%), or both (10%), as appreciated by the Papanicolaou stain. The specimens were processed by the peroxidase-antiperoxidase technique utilizing anti-HSV-1 antibody and 3,3'-diaminobenzidine (DAB) as the chromogen. In six cases, aminoethylcarbazol (AEC) was used for comparison. Twenty-nine of the 33 specimens (88%) stained positively for HSV-1 as did control sections of herpetic encephalitis and esophagitis; there were no false positives with appropriate negative controls. All 12 bronchoscopic specimens revealed virocytes with HSV immunopositivity; in contrast, 17 of 21 (80%) sputum specimens were positive for HSV. The strongest positivity was noted in bronchial brushings and washings whereas the only four negative smears were from sputum specimens. The DAB immunostain was coarser and stronger at the periphery of the cytoplasm, and the hematoxylin counterstain permitted a clear identification of nuclear viral changes. With AEC, the immunostain was more vivid and evenly distributed, but counterstaining was impaired due to the greater solubility of the chromogen. The technique is sensitive, reproducible, and less expensive and time-consuming than electron microscopy (EM) or viral cultures.