The value of cytology and pleural biopsy in the differential diagnostic of nonspecific pleural effusions

A significant percentage of pleural effusions remains without a diagnostic explanation. In such circumstances, the anatomical-pathological result of nonspecific chronic pleuritis should be revised. This is an important issue, not only for the pathologist, but mainly for the pneumologist, who usually makes the clinical-pathological correlation during the routine practice. Although the existence of established criteria is accepted, they are certainly subjective and make the communication by means of a common language difficult, mainly among pathologists. The authors recently studied 311 pleural biopsies with histo-pathological diagnoses of chronic nonspecific pleuritis. All specimens were reviewed and the histo-pathological parameters quantified by stereology. The patients were stratified according to the final diagnosis of their disease, including cases of chronic renal failure, vasculitis, pancreatitis, tuberculosis, cancer, and congestive cardiac failure, in this case considering the pleura as normal. This procedure allowed us to obtain a discriminating model, whose morphological subcriteria classified almost 90% of the nonspecific chronic pleuritis biopsies, according to their final clinical diagnoses, which included true nonspecific chronic pleuritis or tuberculosis pleuritis, paraneoplastic pleuritis, or even normal pleura. By adding to this model the biochemistry or differential cytology of the pleural liquid, its classificatory power reaches 99% of correctness. This study represents the result of the experience acquired over several years in the histo-pathological interpretation of pleural biopsies, based on the correlation between morphology and biochemistry and cytology of the pleural fluid.

Interstitial granulomatous pulmonary diseases: a diagnostic approach for the general pathologist

Some kinds of interstitial pneumonia present a histopathological pattern dominated by sarcoid - necrotizing or non-necrotizing - granulomas, which can be divided into two main groups: infectious and non-infectious. The infectious causes include tuberculosis, histoplasmosis, fungi in general, paracoccidioidomycosis, ascaridiasis, echinococcosis and dirophilariosis. The non-infectious causes include histiocytosis-X, hipersensitivity pneumonia, vasculitis, lymphomas, sarcoidosis, and pneumoconioses such as silicosis and berylliosis. The purpose of this review is to provide a practical guideline to enable general pathologists to make the differential diagnosis of granulomatous pulmonary diseases. For this purpose, anatomical-clinical-radiological correlations will be presented and targeted to each diagnosis discussed. Whenever a granulomatous inflammatory process is in progress, the search for infective agents by direct observation, by culture, and by histochemical methods should be mandatory. The histological aspects of infectious granulomas to be analyzed should include their random histo-anatomical location, the type of inflammatory reaction, and necrosis. A panel of complementary reactions (immunohistochemistry and PCR) should identify the infectious agent and, whenever their results and the culture are negative, the possibility of non-infectious granulomatous diseases has to be evaluated. In such cases, the histo-anatomical distribution (bronchocentric, lymphangitic, angiocentric, random), the qualitative characteristics of the lesions (type of necrosis and inflammatory reaction), and the correlation with the X-ray findings will help the diagnosis.