Surfactant Production by Neoplastic Type II Pneumocytes

Abstract

A bronchioloalveolar carcinoma of type II pneumo-cyte differentiation with abundant intraluminal secretion, histochemically and histologically mimicking alveolar proteinosis, is described. The tumor was of the diffuse type, involving almost the entire lower lobe of the left lung. The luminal aspect of the cells showed evidence of apocrine secretion. Ultrastructurally, the cells were characterized by the presence of cytoplasmic lamellar bodies. There were occasional cells with intranuclear tubules, and numerous rounded fragments of cytoplasm were present in the lumen as evidence of the apocrine activity. The intraalveolar secretion was composed of lamellar bodies in various stages of dissolution, tubular myelinlike networks characteristic of surfactant, and amorphous, granular material. This is the first reported instance of morphologic demonstration of surfactant secretion by a bronchioloalveolar carcinoma.

Key Words:

• bronchioloalveolar carcinoma
• type II pneumocyte
• surfactant
• alveolar proteinosis
• apocrine secretion