Immuno histochemistry of cholesterol cleft granulomas in non-specific interstitial pneumonia [NSIP]

Cholesterol cleft granulomas with clusters of giant cells were noted to be a common feature of Non-Specific Interstitial Pneumonia [NSIP]. The giant cells commonly seen in granulomas are considered to be macrophage polykaryons formed by the fusion of alveolar macrophages attached to the same endocytic material. This study aimed to define the cell populations involved in the granulomas. The granulomas of 16 patients with cryptogenic fibrosing alveolitis [five cases with the histological features of NSIP, five with those of UIP and six cases of respiratory bronchiolitis] were examined histologically and the use of immunohistochemical markers. Granulomas were discrete, compact and present only in alveolar spaces. The granulomas contained central clefts surrounded by mononuclear and multinucleated giant cells, both of which were CD68 positive. The cells outside the granulomas and those lining the adjacent alveolar walls were AE1/AE3 and CAM5.2 positive and CD68 negative. Our observations indicate that cholesterol cleft granulomas occur with high frequency in NSIP, are present within alveolar spaces which are lined exclusively by type II pneumocytes and that external to this the interstitium is fibrotic with accumulations of mast cells. It is our speculation that these are linked in a pathogenetic mechanism related to the progression of NSIP. The results also suggest that the mononuclear and multinucleated cells of cholesterol cleft granulomas are derived from the macrophage-mononuclear cell lineage. The alveolar lining cells are type II pneumocytes which do not contribute to the granuloma cell population. The alveolar lining cells are type II pneumocytes which do not contribute to the granuloma cell population

Lectin histochemistry of cholesterol cleft granulomas in non-specific interstitial pneumonia [NSIP]

Cholesterol cleft granulomas with clusters of giant cells were noted to be a common feature of non-specific interstitial pneumonia [NSIP].This study aimed to define the cell populations involved in the granulomas.The granulomas of 16 patients with cryptogenic fibrosing alveolitis [five cases with the histological features of NSIP, five with those of UIP and six cases of respiratory bronchiolitis] were examined histologically and by the use of immuno- and lectin histochemical markers.Granulomas were discrete, compact and present only in alveolar spaces. The adjacent interstitium usually showed fibrous thickening although granulomas were absent. The granulomas contained central clefts surrounded by mononuclear and multi-nucleated giant cells, both of which were CD68 positive. The cells outside the granulomas and those lining the adjacent alveolar walls were AE1/AE3 and CAM5.2 positive and CD68 negative. The application of an extended lectin panel demonstrated restricted glycoprofiles for multinucleated cells, alveolar macrophages and alveolar lining cells. The glycoprofiles of the first two were similar to each other, but were different from the third. The mononuclear and multinucleated cells of cholesterol cleft granulomas are derived from the macrophage-mononuclear cell lineage and express glyco-proteins with a high mannose content. The alveolar lining cells are type n pneumocytes which do not contribute to the granuloma cell population