Fig. 1

Pulmonary CT scan. A soft tissue density nodule was seen in the apical segment of the upper lobe of the right lung; the size was about 17 × 13 mm (A lung window, B arterial phase). Imaging features of MALT lymphoma in the lateral segment of the middle lobe of the right lung (C lung window, D arterial phase). Postoperative histopathological changes. E Squamous cell infiltrative growth (H&E, magnification × 100). F Cancer cells positive for P40 (P40, IHC, magnification × 100). G The morphology was more consistent with lymphoid cells infiltrating in sheets, with scant cytoplasm and deep nuclear staining (H&E, magnification × 200). H Cells CD20 diffusely (+) (CD20, IHC, magnification × 200). I CD21 staining revealed a network of follicular dendritic cells (CD21, IHC, magnification × 200). J CD3 negative (CD3, IHC, magnification × 200)