Tuberc Respir Dis TRD Tuberculosis and Respiratory Diseases 1738-3536 The Korean Academy of Tuberculosis and Respiratory Diseases 10.4046/trd.2008.65.2.147 Case Report Consolidative Bronchioloalveolar Carcinoma Presenting as Pneumonia, and This Led to a Late Diagnosis due to the Improvement after Antibiotic Therapy Jeong Ina M.D. Heo Eun Young M.D. Lee Jae Seok M.D. Yoon Ho Il M.D. Lee Jae Ho M.D. Lee Choon-Taek M.D. Kang Young Ae M.D. Department of Internal Medicine, Lung Institute of Medical Research Center, Seoul National University College of Medicine, Seoul, Department of Internal Medicine, Respiratory Center, Seoul National University Bundang Hospital, Seongnam, Korea. Address for correspondence: Young Ae Kang, M.D. Department of Internal Medicine, Respiratory Center, Seoul National University Bundang Hospital, 300, Gumi-dong, Bundang-gu, Seongnam 463-707, Korea. Phone: 82-31-787-7009, Fax: 82-31-787-4052, mdkang@medimail.co.kr 08 2008 31 08 2008 65 2 147 151 10 06 2008 21 07 2008 Copyright © 2008 The Korean Academy of Tuberculosis and Respiratory Diseases 2008

Non-resolving or slowly resolving pulmonary infiltrates in spite of administering adequate antimicrobial therapy are a clinical diagnostic challenge for physicians. The rate of radiographic resolution varies with the patients' age, the underlying comorbidities, the extent of radiographic involvement, the functional status and the causal pathogens. It is important to differentiate non-resolving or slowly resolving bacterial pneumonia from other uncommon infectious pneumonias or malignancies that require invasive diagnostic techniques to confirm the diagnosis. Bronchioloalveolar carcinoma can present with various clinical and radiographic features. Unfortunately, the radiographic similarity of consolidative BAC to pneumonia often leads to an incorrect diagnosis of pneumonia and possibly significant delays in obtaining appropriate diagnostic studies. We describe here a case of a mixed adenocarcinoma and bronchioloalveolar carcinoma that was initially diagnosed as pneumonia due to the consolidation pattern on the radiography and the patient's initial improvement with antibiotic treatment.

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Initial chest CT (at admission) showed right lower lobe consolidation with pleural effusion and reactive LN enlargement.

Chest images at 16th day after admission showed improved right lower lobe consolidation and pleural effusion after 16 days of antibiotics therapy.

After 2 month of discharge, follow-up chest CT showed decreased pleural effusion but remaining consolidation was still observed at right lower lobe.

After 4 month of discharge, follow-up chest CT showed decreased but remaining consolidation with focal cavitation at right lower lobe.

Resected lung tissue showed mass with necrosis and bleeding.

Tumor cells showed mucinous-bronchioloalveolar pattern composed of tall columnar cells with basal nuclei and pale cytoplasm, resembling goblet cells, with varying amounts of cytoplasmic mucin. It also showd extensive consolidation with numerous alveolar macrophages (H&E stain, ×100).

The resected lung specimen showed invasion which was characterized by significant increase in cytologic atypia, a fibroblastic stromal reaction, and an acinar pattern of growth (H&E stain, ×200).