Figure 2.

Gross, histological and immunohistochemical findings of poorly differentiated adenocarcinoma of the lung. A: On gross examination, the cut surface showed a solid firm and lobulated mass, measuring 32 mm × 30 mm × 29 mm, which looked from gray-whitish to yellow-whitish in color, accompanied with focal necrosis and hemorrhage. The background had no remarkable change. Bar = 1 cm; B: Low to medium power view exhibited a proliferation of medium-sized to large atypical epithelial cells having hyperchromatic pleomorphic nuclei and abundant eosinophilic cytoplasm, predominantly arranged in an acinar or solid fashion with frequent necrotic foci (HE stains). Multi-nucleated giant tumor cells were readily encountered (inset). Bar = 500 μm; C: The tumor nests peripherally involved the vascular vessel (HE stains). Bar = 200 μm; D: In immunohistochemistry, these adenocarcinoma cells were specifically positive for thyroid transcription factor 1 (TTF-1) (left) and Napsin A (right), in nuclear and intracytoplasmic pattern, respectively. Bar = 50 μm.