Fine needle aspiration biopsy of pulmonary hamartomas. Radiologic, cytologic and immunocytochemical study of 15 cases

To review the radiographic, cytologic and immunocytochemical features of pulmonary hamartomas (PHs) diagnosed on fine needle aspiration biopsy (FNAB).

Fifteen consecutive cases of PH, diagnosed on FNAB between January 1987 and February 1993 and confirmed by surgery or follow-up, were studied. In two additional cases PH was offered as a differential diagnosis and was excluded on follow-up. Clinical notes, radiographs, cytologic smears and cell block sections stained routinely and with antibody to S-100 protein, as well as histologic slides, were reviewed.

All cases of PH showed common radiographic features, including peripheral location, round or oval shape, sharp edges and size < 3 cm. Cytologic diagnosis of PH was based on recognition of mesenchymal component, characterized by fibromyxoid stroma, present in 94% of FNABs. Chondroid material was present in 75% of aspirates. In all cases of proven PH, fibromyxoid material showed S-100 protein positivity, characterized by finely granular, brown staining of the stellate cells. In two cases proven not to be hamartomas, the material, suspected to be fibromyxoid or chondroid, failed to show S-100 protein positivity.

These findings confirm the value of FNAB in the diagnosis of PH. Immunocytochemical staining with antibody to S-100 protein is a useful diagnostic tool in confirming the cartilaginous nature of PH. The cytologic findings should be correlated with radiologic and clinical findings before a definitive diagnosis of PH is rendered on FNAB material.