Fig. 1

Pathological findings. a Gross pathological specimen of the thrombus occluding pulmonary artery bilaterally. The specimen consists of an irregular fragment of red-tan hemorrhagic tissue measuring about 1.3 cm in diameter. b Light microscopy of lung tissue section shows an intravascular thrombus of large vessel (arrow). c Lung parenchyma showing inflammatory cells in the pulmonary interstitium (arrows) and in alveolar space. d Lung diffuse interstitial fibrosis is visible (arrow). Numerous CD4+ T lymphocytes (e) and CD68+ macrophages (f) are diffusely present into alveolar septa and around vessels (arrows). Scale bars: a = 1 cm; b = 100 μm; c-f = 50 μm