History: A 56-year-old man complain of chronic cough for 6 months without further clinical problems. The patient was otherwise in good health and showed only a moderate bronchial sound at the left ventral paracordial region.
Investigations: Thorax X-ray revealed an infiltrate in the lingula with segmental borders. The CT scan showed air bronchogramms and bilateral more small infiltrates. DIAGNOSIS, TREATMENT, CLINICAL COURSE: Bronchoscopic transbronchial biopsies revealed a BALT-lymphoma. A seven years old chest X-ray showed the lingual infiltrate in nearly the same extension as the current X-ray. Because of the disseminated manifestation, the slow course and the good performance status we did not start a palliative chemotherapy so far.
Conclusion: Any pulmonary infiltrate which looks like pneumonia must be given a definite diagnosis if there are no clinical signs of infection.