First published online September 17, 2007
British Journal of Radiology (2007) 80, 803-806
© 2007 British Institute of Radiology
doi: 10.1259/bjr/27788443
Computed tomography characteristics of primary pulmonary lymphoepithelioma-like carcinoma
Chung-Jen Huang, MD
1
Kwan-Yee Chan, MD
2
Ming-Yuan Lee, MD
3
Li-Han Hsu, MD
1
Nei-Min Chu, MD
4
An-Chen Feng, MPH
5
Chih-Teng Yu, MD
6 and
Horng-Chyuan Lin, MD
6
1 Division of Pulmonary Medicine and Intensive Care Medicine, 2 Department of Radiology, 3 Department of Pathology and Laboratory Service, 4 Division of Hematology and Medical Oncology and 5 Department of Research, Koo Foundation Sun Yat-Sen Cancer Center, Taipei, Taiwan, 6 Department of Thoracic Medicine, Chang Gung Memorial Hospital, Taoyuan, Taiwan
Correspondence: Dr Chung-Jen Huang, Division of Pulmonary Medicine and Intensive Care Medicine, Koo Foundation Sun Yat-Sen Cancer Center, 125 Lih Der Road, Pei-Tou District, Taipei 11259, Taiwan, Republic of China. E-mail: huang600517{at}yahoo.com
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Abstract
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Primary pulmonary lymphoepithelioma-like carcinoma is a very rare subtype of lung cancer. This report documents the CT features of 16 Chinese patients diagnosed with primary pulmonary lymphoepithelioma-like carcinoma from January 1999 to December 2005. A pre-treatment CT was used to assess the tumour site, size, borders, pleural and vascular involvement, and the presence of lymph node involvement. The majority of the patients were female non-smokers with centrally located tumours. Lymph node involvement and bronchial and vascular encasement were frequent. In an Epstein–Barr virus endemic area, primary pulmonary lymphoepithelioma-like carcinoma is an important differential diagnosis to consider.
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Introduction
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Lung cancer is the most common cause of cancer death worldwide. Primary pulmonary lymphoepithelioma-like carcinoma (LELC) is a very rare subtype of non-small cell lung cancer. LELC is mostly found in the nasopharynx or other parts of the foregut. Primary pulmonary LELC was first reported in 1987, and a total of only about 100 cases have been reported to date in the English language literature [1–12]. It is strongly associated with Epstein–Barr virus (EBV) infections and most of the reported cases have occurred in regions of Southeast Asia, such as Hong Kong, Taiwan and Guangdong. Primary pulmonary LELC is usually found in younger non-smokers and has a better prognosis than other types of non-small cell lung cancer because it is relatively sensitive to chemotherapy or radiotherapy [1]. Because it is rarely seen, little information exists on the diagnostic imaging characteristics of this neoplasm [2, 12]. Our study documents the CT findings of this rare type of lung cancer.
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Methods and materials
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Koo Foundation Sun Yat-Sen Cancer Center is a tertiary referral cancer centre and Chang Gung Memorial Hospital is a tertiary referral general hospital. The databases of the two hospitals were reviewed for all patients with biopsy-proven primary pulmonary LELC. Nasopharyngeal examination was performed routinely in these patients to exclude primary nasopharyngeal carcinoma. From January 1999 to December 2005, a total of 19 Chinese patients were diagnosed with LELC in these two hospitals, of whom 16 patients had undergone a CT scan at initial diagnosis and were included in this study. All of the pre-treatment CT scans were performed with a General Electric CT scanner (CT9800, CTi, VCT; GE Medical Systems, Milwaukee, WI) before and after the administration of intravenous contrast (100 ml Omnipaque 300 mg ml–1, injection rate of 1.5–2.5 ml s–1). Each CT study was performed with a slice thickness of 5 mm and an interval of 5 mm from the thoracic inlet to the caudal tip of the liver. Both lung and soft tissue windows were reviewed. The images were jointly reviewed by a radiologist and a chest physician. The tumour site (peripheral or central), size (defined as the product of the two maximum diameters), tumour borders (well-defined, spiculated, ill-defined) and the presence of pleural and vascular involvement were evaluated. Tumours were defined as "central" when they were located in the inner two-thirds of the lung with close proximity to the mediastinum, main bronchi and central pulmonary vessels. Lymph node involvement was defined as focally enlarged lymph nodes (>1 cm in short axis diameter). The overall TNM stage was evaluated and recorded. In situ hybridization of EBV-encoded small nuclear RNA (EBER) was performed on the pulmonary histological specimens from seven patients.
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Results
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The demographic data and results including age, sex, smoking history, tumour location and size, presence of metastastic disease and initial TNM stage are shown in Table 1
. The majority of patients were female non-smokers with advanced-stage disease. The CT features of the 16 patients are presented in Table 2. Most of the cases were of a centrally located tumour with lymph node involvement commonly seen (Figures 1–5). Vascular and bronchial encasement or cardiac invasion was frequent. The size of the primary tumours was variable. In situ hybridization of EBER in the pulmonary specimens was positive in seven patients.
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Table 2. CT characteristics of all patients with primary pulmonary lymphoepithelioma-like carcinoma at initial diagnosis
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Figure 1. A 65-year-old woman with primary pulmonary lymphoepithelioma-like carcinoma in the right lower lobe. The tumour is centrally located with bronchial encasement and cardiac invasion.
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Figure 2. A 46-year-old woman with primary pulmonary lymphoepithelioma-like carcinoma in the right lower lobe. The tumour is centrally located.
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Figure 3. A 51-year-old woman with primary pulmonary lymphoepithelioma-like carcinoma in the right middle lobe. The CT scan shows a pulmonary nodule with vascular encasement.
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Figure 4. A 61-year-old woman with primary pulmonary lymphoepithelioma-like carcinoma in the left lower lobe. The CT scan shows a large tumour with a pleural effusion.
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Figure 5. A 60-year-old woman with primary pulmonary lymphoepithelioma-like carcinoma in the left lower lobe. The tumour is centrally located with bronchial encasement.
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Discussion
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Primary pulmonary LELC is a very rare subtype of lung cancer and most reported cases are from small patient series. In addition, there are very limited data available on its radiographic features. In the study from Ooi et al [2], a total of 10 patients with LELC were reported and the CT features were compared with other types of non-small cell lung cancer. In their study, larger centrally located tumours with well-defined borders, peribronchovascular lymph node involvement and vascular encasement were considered to be specific CT features. Our patient group has confirmed the majority of their findings, although our tumour size was variable.
Primary pulmonary LELC shows significant demographic differences from other types of non-small cell lung cancer. Most patients appear to be female and non-smokers as seen in our study and a number of other studies [1, 3, 5–9, 12]. As non-small cell lung cancer more commonly affects men and smokers rather than women and non-smokers, there is presumed to be a difference in the causative pathophysiology. In situ hybridization of EBER was positive in the specimens of all seven patients in which it was performed. Although LELC is considered to be strongly associated with EBV in nucleic acid hybridization and in situ hybridization studies [11], female and non-smoker predominance cannot be explained only by the viral infection, as in an EBV endemic area the virus is transmitted equally to both sexes, suggesting that either an unknown carcinogen or other gender-related factor may play a role in its pathogenesis.
Pulmonary LELC has very similar pathological features to undifferentiated carcinoma arising in the nasopharynx. Both of these cancers occur in EBV-endemic areas, such as Southeast Asia, but the prevalence of nasopharyngeal carcinoma is much higher than primary pulmonary LELC. As such, a nasopharyngeal exam is essential in patients with a possible diagnosis of pulmonary LELC to exclude metastatic disease from a primary nasopharyngeal carcinoma.
In conclusion, primary pulmonary LELC frequently manifests as a centrally located tumour with lymph node involvement and vascular and bronchial encasement. Although the CT features are not specific when compared with other types of non-small cell lung cancer, it should be considered as an important differential diagnosis in EBV-endemic areas.
Received for publication August 8, 2006.
Revision received November 3, 2006.
Accepted for publication January 9, 2007.
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Abstract
Introduction
