Diffuse Large B-Cell Lymphoma Arising from the Lesion of Chronic Lobar Atelectasis.

Pulmonary lymphoma is rare, accounting for < 1% of primary lung cancers. Most primary pulmonary lymphomas (PPL) are low-grade mucosa-associated lymphoid tissue (MALT)-type, and among PPL, diffuse large B-cell lymphoma (DLBCL) is extremely rare. In contrast, there has been an increase in the incidence of DLBCL among patients with autoimmune disorders and recurrent or chronic bacterial infection. A subset of DLBCL has been reported to develop through transformation of preexisting or concurrent MALT. The respiratory symptoms are non-specific, and the chest X-ray findings demonstrate the presence of interstitial and mixed alveolar infiltrates, nodular lesions, and localized homogeneous consolidations; the diagnosis of pulmonary DLBCL is thus challenging and often leads to a misdiagnosis or delayed diagnosis. We herein report a case of DLBCL which was assumed to have arisen from the lesion of chronic atelectasis that was successfully diagnosed by endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA). A 74-year-old woman with diffuse bronchiectasis and chronic atelectasis of the left lower lobe suffered from productive cough and high fever. Increased airway filling with mucoid secretion was repeatedly observed within the area of atelectasis with bronchiectasis, and left lower lobe atelectasis developed. Subsequently, the hilar and mediastinal lymph nodes gradually became enlarged, and DLBCL was pathologically confirmed. In the present case, DLBCL was considered to have arisen in the lesion of chronic atelectasis. Physicians should recognize that DLBCL may develop at the site of chronic atelectasis during disease course of diffuse bronchiectasis, and thus DLBCL may be misdiagnosed as superimposed infection of chronic atelectasis.