Hermansky-Pudlak Pulmonary Fibrosis
Hermansky-Pudlak Pulmonary Fibrosis

Higher magnification reveals these clear cells to be admixed with stromal chronic inflammation and occasional lymphoid aggregates (arrow). The amount of admixed inflammation alone would argue against UIP of idiopathic pulmonary fibrosis, and the clear cells are a completely unexpected finding for that diagnosis. The inset shows the characteristic vacuolated clear cells lining (and in) distorted alveolar spaces. These cells are positive for lung epithelial (TTF-1) or macrophage (CD68) markers. The material in these cells (and in pulmonary macrophages) has been referred to as "ceroid lipofuscin" and is presumably an accumulation of cellular lysosomal products resulting from a genetic defect in the Golgi apparatus. Hematoxylin and eosin stain 100x original magnification; inset 400x magnification.