Extrinsic allergic alveolitis as an uncommon diagnostic pitfall in lung cytology

House paints, the industrial products of toxic chemicals are known to be linked with severe respiratory disturbances especially in inadequately ventilated places. In this study, we aimed to report a biopsy-proven case of extrinsic allergic alveolitis (EAA) who presented with nonspecific respiratory symptoms 1 month after having her whole house interior painted. At CT scanning, we observed the ground glass opacities and the micronodular pattern typical for EAA and also a solid, consolidative lung area, highly suggestive of malignancy. The case initially was misinterpreted as a malignant tumor both radiologically and cytologically at CT-guided transthoracic fine needle aspiration biopsy. The final pathologic diagnosis was given as EAA on frozen section performed during thoracotomy operation. The patient received short-term steroid treatment and has been doing well for the last 7 months after her operation. As a conclusion, when assessing a cytologic material from a patient who has got a solid lung mass and also a history of chemical dye exposure, consolidative mass formation which is a rare form of EAA should always be kept in mind. Another final point is that the appropriate ventilation should be achieved if the exposure with the house paint chemicals is inevitable.