Radiographic improvement following smoking cessation. The chest CT images on the left side were performed in an active one pack/day 37 year old smoker with biopsy-proven PLCH. The representative chest CT images demonstrate diffuse nodular infiltrates in both upper and lower lung fields. The patient quit smoking 2 months after the first chest CT was performed. The representative chest CT images on the right side were performed one year after the first chest CT was obtained, and show considerable improvement in the nodular infiltrates following smoking cessation. The patient did not receive corticosteroid or other immunosuppressive therapy.