Pulmonary localized AA type amyloidosis with cyst-like structures and marginal zone B-cell lymphoma of the MALT type coexisting independently in the left upper lung.

A 77-year-old man was found to have an abnormal shadow on chest X-ray. Chest CT indicated four lesions in both lungs. One was located in the left S1+2. The others were located in the left S3, right S8 and S9, and those had cyst-like structures. The tumor in S1+2 showed diffuse proliferation of atypical lymphocytes, which were positive for CD20. The diagnosis of pulmonary mucosa-associated lymphoid tissue lymphoma was made. The tumor in S3 was composed of eosinophilic amorphous deposits. The diagnosis of amyloidosis was confirmed by polarized light examination. After oxidation with permanganate solution, the Congo red staining disappeared.