Mucosa-associated lymphoid tissue lymphoma presenting as ground glass nodule

Pulmonary mucosa-associated lymphoid tissue (MALT) lymphoma rarely occurs. It is difficult to distinguish MALT lymphomas and pre-invasive lesions according to radiological findings. We report a case of 60-year-old woman who was found to have a rapidly growing ground glass nodule (GGN) on her left lower lobe, discovered on follow-up chest computed tomography. The radiological image was pure GGN, which was compatible with a pre-invasive lesion, such as non-mucinous adenocarcinoma in situ. Wedge resection was performed and the final diagnosis was stage I MALT lymphoma. After surgery, she was doing well with no evidence of recurrence one year later. We believe a lung biopsy for rapidly growing GGN is recommended in order to confirm the pathological diagnosis.