Abstract

An instance of a squamous carcinoma of the lung with osteocartilaginous metaplasia in the stroma is reported. This unusual stromal response is similar to extraskeletal osteocartilaginous metaplasia in any other site, and is a change which occasionally is produced by a variety of pathological and experimental conditions, including gastrointestinal adenocarcinoma and urinary tract epithelial carcinoma. This stromal response should be differentiated from a true sarcomatous participation in the tumour.