Fig. 1

Axial slice of CTPA performed during the patient’s first admission. CTPA demonstrated small centrilobular soft tissue nodules with branching linear opacities forming a tree-in-bud appearance. This is most often caused by obstruction of small airways by, for example, mucus. In PTTM, however, it is caused by tumour cells in distal arterioles and the resultant inflammation that follows. The differential diagnosis for pulmonary nodular infiltrates with mediastinal lymphadenopathy, particularly the small volume adenopathy seen in our patient, is wide-ranging. It includes both malignant causes such as lymphoma as well as benign causes such as tuberculosis, inflammatory nodules, and sarcoidosis