Whipple bacilli within the tunica media of pulmonary arteries.

In the lungs of two patients dying with Whipple's disease, we found Schiff-positive bacilli within the tunica media of many pulmonary arteries. Tissue was examined from all five lobes of the lungs in both cases. There were no pulmonary emboli and no alveolar lesions of Whipple's disease. Focal degeneration of the tunica media was conspicuous in areas where bacilli were present, and at some sites there was some overlying intimal proliferation. Little inflammatory response was present. All the bacilli within the tunica media were free as single organisms or small clumps, and there were none within macrophages. Macrophages containing bacilli were occasionally found within the adventitia of the pulmonary arteries. The possible role of these lesions in the pathogenesis of chronic pulmonary arterial disease merits consideration.