A 60-year-old man with pharyngeal carcinoma developed spontaneous pneumo thorax. A biopsied lung tissue revealed an extensive granulomatous reaction to some yellow material. Because of the patient's frequent aspirations of the liquid diet which was mixed with an artificial lemon flavor, It is considered that the aspirated material provoked the pulmonary reaction and possibly the pneumo thorax. An energy dispersive X-ray analysis of the biopsied lung tissue aided in excluding the possibility of the pumonary reaction and the yellow material being of ubiquitous pneumoconiotk origin.