Clinical diagnosis
Case 271
【Progress】
She was introduced to university hospital for histologic examination and thereafter, chemotherapy. We presented this case for typical radiologic and clinical findings: consolidative opacity on CT and no respiratory symptoms.
【Discussion】
Alveolar cell carcinoma, bronchioalveolar carcinoma and terminal bronchiolar carcinoma are synonyms. It is thought to arise from terminal bronchioles and spread to alveolar cells (1, 2). It grows along with alveolar cells line, indicative of preserving pulmonary function. Histologic findings indicated similar to carcinoma in situ. Its etiology is unknown and not related to smoking (1, 2).
Alveolar cell carcinoma occurs 3-4% of all lung cancers and often emerges in Asian woman. It can arise from multicentric. It is usually slowly growing without destructing alveolar cells, indicative of causing less symptoms. About 50% are asymptomatic and symptoms include cough and shortness of breath (1, 2).
Radiologic findings include consolidation with air bronchogram and ground glass opacity in the margin that mimic pneumonia, pulmonary hemorrhage and malignant lymphoma.
Our case is a woman who never smoke and whose symptoms are palpitation and shortness of breath, indicative of almost no respiratory symptoms despite of marked radiologic findings of multicentric consolidation.
The configure of peripheral adenocarcinoma is known to be expansive and oval with irregular margin, destroying lung parenchyma and supporting tissue. Meanwhile, the configure of small-sized alveolar cell carcinoma on CT is not always expansive, not oval but polygonal (Figs. 1-3). This is probably because this tumor grows along with alveolar cell line and then, grows like occupying the lobules.
The configure of bronchiolitis is centrilobular granule or small nodule usually demonstrated on CT. The active inflammation of bronchiolitis occurs from the center of lobules, indicative of bronchiolitis coming from respiratory tract (3). Alveolar cell carcinoma arises from terminal bronchiole, indicating that alveolar cell carcinoma occurs more peripheral than bronchiolitis. The different arising sites induce the distinct configuration between bronchiolitis and alveolar cell carcinoma.
Among other lesions associated with pulmonary consolidation, pulmonary lymphoma is listed to be differentiated. Bacterial pneumonia and pulmonary hemorrhage are also included but these are symptomatic such as fever and hemoptysis. Pulmonary lymphoma and alveolar cell carcinoma are often asymptomatic. Radiologic findings of both tumors are characteristic of air bronchogram in consolidative lesion. The difference is that the configuration of pulmonary lymphoma is oval and expansive lesion with traversing bronchus (4, 5), while that of alveolar cell carcinoma is not oval but polygonal or expansive along with bronchus occupying lobules (1, 2). In our case, multiple lesions have consolidative opacity such as pneumonia and the configuration of the small lesion was polygonal.
【Summary】
We presented a sixty four-year-old female suffering from palpitation and short breath on exertion. Laboratory test revealed no evidence of abnormality. Chest CT depicted multiple opacity lesions with consolidation in bilateral lung, including several small lesions whose configuration were polygonal. It is borne in mind that in case of pulmonary consolidative lesions on CT, pneumonia, pulmonary hemorrhage, pulmonary lymphoma and alveolar cell carcinoma are listed. The occupying site of these lesions is alveolar space but not bronchus. Alveolar cell carcinoma is identical to bronchioalveolar carcinoma and terminal bronchiolar carcinoma because the origin comes from terminal bronchioles. Alveolar cell carcinoma grows along with alveolar line without destruction of pulmonary parenchyma, preserving pulmonary function. The difference between alveolar cell carcinoma and pulmonary lymphoma is that the configuration of pulmonary lymphoma is oval and expansive with traversing bronchus, while that of alveolar cell carcinoma is often polygonal or expansive with patent bronchus occupying lobules.
【References】
1.Belgrad R, et al. Alveolar-cell carcinoma (terminal bronchiolar carcinoma). A study of surgically excised tumors with special emphasis on localized lesions. Radiology; 1962;79:789-98
2.Saul Suster MD, Cesar A. Moran MD, in Diagnostic Pathology: Thoracic (Second Edition), 2017
3.Ryu JH, et al. Recent advances in the understanding of bronchiolitis in adults. Version 1. F1000Res. 2020; 9: F1000 Faculty Rev-568. Published online 2020 Jun 8. doi: 10.12688/f1000research.21778.1
4.Raman SP, et al. Imaging of thoracic lymphatic diseases. AJR Am J Roentgenol. 2009;193 (6): 1504-13.
5.Lewis ER, et al. Lymphoma of the lung: CT findings in 31 patients. AJR Am J Roentgenol. 1991;156 (4): 711-4. AJR Am J Roentgenol (abstract) - Pubmed citation
2022.7.8