Inflammatory pseudotumor of the lung diagnosed as granulomatous lesion by preoperative brushing cytology-A case report

The clinical and cytological features of an inflammatory pseudotumor of the lung were studied. The patient was a nine-year-old boy in whom roentgenograms of the chest revealed a solitary circumscribed round mass, which was diagnosed as a granulomatous lesion by preoperative brushing cytology. As the mass increased slowly in size in spite of therapy for tuberculosis, an open lung biopsy was performed. In cytological specimens, short spindle-shaped cells tended to be arranged in a storiform pattern, and had basophilic cytoplasm, enlarged oval nuclei with slight atypia, thinner nuclear membranes, and a finer chromatin structure. These findings suggested their origin as epitheloid cells. Foreignbody-type multinucleate histiocytes were seen, but there was little necrotic substance and the background was clear. The diagnosis of an inflammatory pseudotumor was made by histopathological study. This lesion is a rare granulomatous lesion that must be distinguished from malignant tumors. However in none of the previously reported cases was the diagnosis established preoperatively. When brushing cytology of an intrapulmonary lesion shows histiocytic spindleshaped cells in a storiform pattern, but smears and cultures for tuberculosis are negative, particularly in children, it is necessary to examine cytological specimens carefully and take into consideration the possibility of an inflammatory pseudotumor.