Fig. 1

Radiological, histopathological, and immunohistochemical features of pulmonary minimally invasive mucinous adenocarcinoma. Chest CT revealed a solid nodule measuring 1.9 cmx1.6 cm in the posterior basal segment of the right lower lobe (A, arrow) with irregular margins and slight enhancement (B, arrow). The resected tumor specimen showed a predominantly lepidic pattern with mucous secretion under low-power view (C). Middle-power magnification revealed tumor cells with abundant apical cytoplasmic mucin and small, basally oriented nuclei growing along the surface of the preserved alveolar walls (D). The partial tumor exhibited an invasive pattern of infiltrative glands lined by tumor cells containing abundant intracytoplasmic mucin (E). The focal area exhibited atypical goblet cell hyperplasia (F, arrows) in the bronchial epithelium (F, triangles). (Magnification x100). Immunohistochemical analysis revealed positive staining for CK7 (G) and negative staining for TTF-1 (H). CK5/6 staining revealed no evidence of basal cell layer (I). (Magnification ×100)