BAL in the diagnosis of smoking-related interstitial lung diseases: review of literature and analysis of our experience.

The group of interstitial lung diseases (ILDs) is formed by respiratory tract disorders, whose aetiology is unknown in the majority of cases, the clinical course differs and the prognosis is generally serious. Some of the ILDs have a potential relation to tobacco smoking and are known as smoking-related ILDs (sr-ILD). Bronchoalveolar lavage fluid (BALF) examination is one of the initial procedures in the diagnosis of ILD. Despite the fact that histological confirmation is the gold standard in ILD diagnosis in many studies, the number of reported biopsies was low. In this review we present the results of BALF examinations of patients with sr-ILD and discuss their value in the differential diagnosis with other types of ILD. An extremely high total cell count (about 50 x 10(6) cells) with significant predominance of pigmented alveolar macrophages is a characteristic pattern of BALF in sr-ILD. The greatest challenge in BALF cytology interpretation is to distinguish sr-ILD and idiopathic pulmonary fibrosis (IPF). IPF is characterised by an elevated proportion and absolute count of lymphocytes and neutrophils; in addition, BALF lymphocytosis is higher in non-specific interstitial pneumonia than in usual interstitial pneumonia (UIP). The population of alveolar macrophage of patients with sr-ILD differs markedly from the foamy and vacuolated cells that predominate in IPF/UIP. Thus, the absence of pigmented cells rather excludes sr-ILD and indicates other types of ILD. To summarise, the place of BALF in the diagnosis of sr-ILD seems to be established.