Diagnosis of Pneumocystis carinii pneumonia by cytologic evaluation of papanicolaou‐stained bronchial specimens

Abstract

To evaluate the sensitivity and specificity of diagnosing Pneumocystis carinii pneumonia (PCP) by Papanicolaou-stained bronchial brushing and wash/lavage specimens obtained by fiberoptic bronchoscopy, the cytologic preparations and clinical records from 58 immunocompromised patients were reviewed. Bronchial brushings and wash/lavage specimens were examined using methenamine silver (Grocott) and Papanicolaou stains. Pneumocystis carinii pneumonia was recognized with Papanicolaou stain by identifying distinctive alveolar casts, which frequently contained collections of encysted sporozoites. Thirty cases of PCP were identified, and Grocott-stained bronchial wash/lavage specimens were positive in 29 instances (97%). Grocott staining of the transbronchial biopsy was positive for PCP in 18 of 22 specimens (82%). Bronchial brushings were insensitive, yielding a positive specimen in only 30% of cases of PCP. Alveolar casts of PCP were identified by Papanicolaou-stained slides of wash/lavage specimens in 83% of cases of Pneumocystis pneumonia. These proteinaceous alveolar casts were not seen in other pulmonary disorders. Encysted sporozoites were found in 56% of cases in which Papanicolaou-stained alveolar casts were identified. We conclude that the diagnosis of PCP can be made rapidly and reliably on the Papanicolaou-stained bronchial wash/lavage or bronchial brush specimens by detecting the characteristic alveolar casts, which contain P. carinii-encysted sporozoites. The presence of encysted sporozoites within alveolar casts is pathognomonic for PCP, and methenamine silver stains can be eliminated in those cases in which encysted sporozoites are identified.

British Thoracic Society guideline for diagnostic flexible bronchoscopy in adults: accredited by NICE

“…TBLB has been reported to have a comparable yield to BAL in cases of P jiroveci pneumonia in some studies,171 199 200 although other studies have shown it to be inferior175 176 and some have shown it to have higher sensitivity than BAL 177. Since TBLB carries the risk of pneumothorax of between 2.5% and 3.7%,176 177 it is not recommended in patients with suspected P jiroveci pneumonia.…”

“…Brush biopsies to diagnose P jiroveci pneumonia have been consistently found to have lower sensitivity compared with BAL, with reported sensitivity between 29% and 52% 171 175 176 199. Due to its limited sensitivity, brush biopsy has a limited role in this setting.…”

Rapid diagnosis of pneumocystis carinii infection in aids by cytocentrifugation and rapid hematoxylin‐eosin staining

“…,~,~~-~~ Fleury and others15 used cytocentrifugation and Papanicolaou staining to determine differential cell populations in BAL fluid. Dugan et al 4 and Stanley et al' used standard centrifugation followed by cytocentrifugation and Papanicolaou staining to diagnose P. carinii.…”

Update on special techniques in routine cytopathology.

“…More florid cases of infection can be detected by recognition of the characteristic exudate in routine Papanicolau stained material. 40 The standard special stain to highlight the cyst walls is a Grocott silver stain. This laborious and time consuming technique has been accelerated by the use of microwaves,4' but judgment most be exercised to avoid over or understaining, particularly as cytological control material may not always be available and histological control material is not directly comparable.…”