Immunohistochemical study of a patient with diffuse pulmonary corpora amylacea detected by open lung biopsy

The chest radiographs of an asymptomatic 58-year-old Japanese man with pulmonary corpora amylacea (PCA) revealed bilateral patchy and nodular infiltrates. Lung specimens obtained by open lung biopsy were histochemically and immunohistochemically analyzed. In all sections of dissected lung tissue, hematoxylin and eosin staining revealed homogeneous eosinophilic acellular round bodies (50-100 microm in diameter) containing granular black pigments in the alveolar spaces. Some round bodies were surrounded and phagocytized by alveolar macrophages. The laminated round bodies stained positively with PAS and Congo red. In addition, many of the rounded bodies contained particles which stained positively with Berlin blue. Immunohistochemical staining for epithelial membrane antigen (EMA) as well as PE-10 was distinctively positive. This is a very rare case of diffuse PCA found by open lung biopsy. Immunohistochemical examination suggested that PCA consisted of pulmonary surfactant protein and epithelial membrane antigen.