Japanese Journal of Clinical Oncology 31:82-85 (2001)
© 2001 Foundation for Promotion of Cancer Research
Nodular Thickening of Interlobar Fissures: an Early Manifestation of Malignant Mesothelioma: A Case Report
1First Department of Internal Medicine and 2Department of Diagnostic Pathology, Kagawa Medical University, Kagawa, Japan
 |
ABSTRACT |
|---|
 TOP ABSTRACT INTRODUCTIONCASE REPORTDISCUSSIONREFERENCES |
|---|
Two men with occupational exposure to asbestos were admitted to our hospital with minute pleural changes on their chest CT image. Conventional computed tomography (CT) scans of the chest showed slightly thickened interlobar fissures and a small amount of pleural effusion. In addition, high-resolution CT showed small nodular opacities on interlobar fissures. There were no intrapulmonary mass shadows, pleural plaques or other extrapulmonary mass shadows. These roentgenographical findings were very similar to each other. Hyarulonic acid values obtained from their pleural fluid were extremely high. Finally, we diagnosed them as having malignant mesothelioma using an immunocytochemical technique and electronmicroscopy. We conclude that HRCT is helpful in the diagnosis of malignant mesothelioma, particularly in its early manifestation such as nodular opacities of interlobar fissures.
|
INTRODUCTION |
|---|
|
TOPABSTRACTINTRODUCTIONCASE REPORTDISCUSSIONREFERENCES |
|---|
A number of benign and malignant diseases may cause diffuse pleural abnormalities. The most common causes are asbestos-related pleural fibrosis, fibrothorax, emphysema, metastatic disease and mesothelioma. The characteristic computed tomography (CT) appearances of these and other diffuse pleural diseases have been described (1). However, a few studies have analyzed the value of CT in the differential diagnosis of diffuse pleural disease (1–5). Since diffuse pleural abnormalities usually consist of various degrees of pleural thickening, calcification and effusion, an overlap of the CT manifestations of the different benign and malignant pleural diseases would be expected.
The CT differentiation of benign and malignant pleural disease is important because the specific diagnosis is often difficult to make by clinical criteria, pleurocentesis and percutaneous pleural biopsy. Not uncommonly, a diagnostic thoracotomy is required because of the need to assess the growth pattern of disease and to obtain a relatively large amount of tissue for histological, immunocytochemical and ultrastructural studies (6).
Mesothelioma is the most common primary pleural tumor arising from cells which also line the serosa of the peritoneum, the pericardium and the trunca vaginalis of the testes, the pleura being the most common site. Among pleural mesotheliomas, 75% are diffuse and 25% are local (3). Diffuse mesothelioma is almost always malignant. Although these patients rarely live more than 2 years, a few reports described early manifestation of malignant mesothelioma on CT scan (3,6).
Recently we experienced two cases of malignant mesothelioma. In this paper, we will emphasize the radiological findings of early pleural change caused by malignant mesothelioma.
|
CASE REPORT |
|---|
|
TOPABSTRACTINTRODUCTIONCASE REPORTDISCUSSIONREFERENCES |
|---|
Case 1
A 56-year-old man, a former smoker, with occupational exposure to asbestos (a car mechanic) for 38 years, was admitted to our hospital because of a right pleural effusion on his chest X-ray film obtained during a regular physical check up (Fig. 1A). He complained of slight general fatigue, but a physical examination revealed nothing remarkable. Laboratory examination was also unremarkable. Conventional CT scans of the chest disclosed slightly thickened interlobar fissures and a small amount of pleural effusion. High-resolution CT (HRCT) (240 mA, 1.0 mm slice thickness at intervals of 7.5 mm) showed small nodular opacities on interlobar fissures and parietal pleural irregularities (Fig. 1B). Sagittal images of multiplanar reconstruction (MPR) using multidetector row CT of 0.5 mm slice thickness also showed fine nodular opacities on interlobar fissures (Fig. 1C). There were no intrapulmonary mass shadows, pleural plaques or other extrapulmonary mass shadows. Pleurocentesis yielded bloody fluid and it showed an exudate (protein 4.6 g/dl, LDH 860 U/ml). The carcinoembryonic antigen (CEA) and hyaluronic acid values of the pleural fluid were 0.5 ng/ml (normal value, <2.5 ng/ml) and 320 000 ng/ml (normal value, <100 000 ng/ml), respectively. Although metastatic adenocarcinoma was suspected from initial cytological examination, the cytoplasm of these cells obtained from the pleural fluid contained glycogen and hyaluronic acid immunocytochemically. The tumor cells also showed immunocytochemical positivity for cytokeratin, epithelial membrane antigen and vimentin. In contrast, all the tumor cells were negative for CEA. Ultrastructurally, the tumor cells had long, thin microvilli, abundant intermediate filaments, intracytoplasmic lumina and long desmosomes (Fig. 1D). Therefore, we diagnosed him as having malignant mesothelioma. Although he was treated with combination chemotherapy (carboplatin, doxorubicin and etoposide), there was no response.
|
Case 2
A 61-year-old man with occupational exposure to asbestos (a maker of asbestos tubes) for 40 years was admitted to our hospital because of fever elevation of unknown origin. His fever failed to improve completely with antibiotics taken for 1 month. He had smoked 20 cigarettes daily for about 40 years. His physical and laboratory examinations were unremarkable on admission. The chest roentgenogram was also unremarkable. Conventional CT scans of the chest showed slightly thickened left interlobar fissures and an extremely small amount of pleural effusion. HRCT showed small nodular opacities on interlobar fissures and mediastinal pleura (Fig. 2A). There were no intrapulmonary mass shadows, pleural plaques or other extrapulmonary mass shadows. These findings were identical with those in case 1. A month after admission, the pleural effusion in his left hemithorax had increased rapidly. Pleurocentesis yielded bloody fluid and it showed an exudate (protein 4.1 g/dl, LDH 521 U/ml). The carcinoembryonic antigen (CEA) and hyaluronic acid values of pleural fluid were 1.2 ng/ml and 540 000 ng/ml, respectively. The histological and ultrastructural examination confirmed that the tumor was a malignant mesothelioma. Although he was treated with combined chemotherapy (cisplatin, adriamycin and etoposide), the tumor was progressive (Fig. 2B).
|
|
DISCUSSION |
|---|
|
TOPABSTRACTINTRODUCTIONCASE REPORTDISCUSSIONREFERENCES |
|---|
Malignant mesothelioma is of special interest because of its poor prognosis and its association with asbestos exposure. Patient inhalation of asbestos fibers may be related to occupational exposure, particularly in the insulation, demolition, shipbuilding, textile, roofing, ceramic, mining and milling industries. The time interval from the first exposure to the development of malignant mesothelioma is 20–50 years (3). Therapeutic results remain poor and cure of malignant mesothelioma is rare. Local treatment such as surgery or radiation therapy are technically difficult because of the extent of disease (7,8). Malignant mesothelioma continues to be a chemo-resistant tumor. Since malignant mesothelioma is rare, study of this tumor has been hampered by the limited number of available patients in any given institution.
CT is particularly valuable in assessing the extent of malignant mesothelioma as well as establishing the presence of pleural effusion or parenchymal disease obscured by a pleural effusion. The extent of the pleural mass and particularly its spread into pleural fissures and along the mediastinal pleura are well seen with CT studies. CT can document the spread of a tumor into the abdomen and identify rib destruction and extra-thoracic extension, the presence of pulmonary nodules, the separation of pleural from parenchymal nodules and the presence of enlarged mediastinal nodes.
Leung et al. (1) reported that helpful features in distinguishing malignant from benign pleural disease were (1) circumferential pleural thickening, (2) nodular pleural thickening, (3) parietal pleural thickening >1 cm and (4) mediastinal pleural involvement. The specificities of these findings were 100, 94, 94 and 88%, respectively, and the sensitivities were 41, 51, 36 and 56%, respectively. They also suggested that HRCT was more helpful in 19 of 31 mesothelioma cases than conventional CT. In 10 cases, better definition of asbestos-related parenchymal changes was obtained; in the remainder, the higher resolution scans confirmed equivocal mediastinal or fissural involvement and nodular pleural thickening. In our cases, minute changes of the pleura caused by malignant mesothelioma were not documented clearly with conventional CT scans. However, HRCT could well document minute changes of pleura as small nodular opacities. Therefore, we defined that small nodular opacities on interlobar fissures and parietal pleural irregularities which could be detected only in the HRCT scan were an early manifestation of diffuse malignant mesothelioma. Since these minute abnormalities have the potential to develop into nodular pleural thickening or pleural thickening >1 cm, it is important to be aware of the possibility of malignant mesothelioma.
On the other hand, Rusch et al. (2) reported that CT is of limited use in the initial evaluation of malignant mesothelioma because it is difficult to assess (1) chest wall involvement, (2) mediastinal lymph nodes, (3) transdiaphragmatic extention of tumor and (4) peritoneal studding and solid organ metastases <2 mm in size. For these circumstances, magnetic resonance imaging may be superior to CT in determining the extent of disease because it allows better evaluation of apical tumors, diaphragmatic and infradiaphragmatic extension and the relationship between tumor and mediastinal structures. However, as shown in case 1, helical CT with MPR has the potential to display axial coronal and sagittal images that are similar to magnetic resonance images.
Malignant mesothelioma is often misinterpreted as metastatic adenocarcinoma of the lung, ovary or gastrointestinal tract. Occasionally, however, pleural metastases may produce diffuse pleural thickening with masses similar to malignant mesothelioma. In metastatic disease, the CT findings are indistinguishable from those of malignant mesothelioma and produce diffuse nodular pleural thickening that encases the underlying lung (1,3).
In this case, electron microscopy and immunohistochemical analysis are helpful in distinguishing malignant mesothelioma from alveolar and adenocarcinoma, especially in patients with the epithelial subtype (6). In addition, most authors agree that open excisional biopsy is the method of choice to obtain a sample which includes sufficient tissue to identify the characteristic histological elements. Whether HRCT is helpful or not in distinguishing early-stage malignant mesothelioma from metastatic adenocarcinoma is unclear. Further studies are required in this area.
We conclude that HRCT is helpful in the diagnosis of malignant mesothelioma, particularly in its early stage with minute pleural changes.
|
FOOTNOTES |
|---|
+ For reprints and all correspondence: Shuji Bandoh, First Department of Internal Medicine, Kagawa Medical University, 1750–1, Miki-cho, Kita-gun, Kagawa, 761-0793, Japan
|
REFERENCES |
|---|
|
TOPABSTRACTINTRODUCTIONCASE REPORTDISCUSSIONREFERENCES |
|---|
1 Leung AN, Muller NL, Miller RR. CT in differential diagnosis of diffuse pleural disease. Am J Roentgenol 1990;154:487–92.
2 Rusch VW, Godwin JD, Shuman WP. The role of computed tomography scanning in the initial assessment and the follow-up of malignant pleural mesothelioma. J Thorac Cardiovasc Surg 1988;96:171–7.[Abstract]
3 Wechsler RJ, Rao VM, Steiner RM. The radiology of thoracic malignant mesothelioma. Crit Rev Diagn Imaging 1984;20:283–310.[Medline]
4 Heelan RT. CT and MR imaging in the evaluation of pleural masses. Chest Surg Clin N Am 1994;4:431–50.[Medline]
5 McLoud TC. CT and MR in pleural disease. Clin Chest Med 1998;19:261–76.[Web of Science][Medline]
6 Ruffie P. Pleural mesothelioma. Curr Opin Oncol 1992;4:334–41.[Medline]
7 Sugarbaker DJ, Norberto JJ, Bueno R. Current therapy for mesothelioma. Cancer Control 1997;4:326–34.[Medline]
8 Sugarbaker DJ, Flores RM, Jaklitsch MT, Richards WG, Strauss GM, Corson JM, et al. Resection margins, extrapleural nodal status and cell type determine postoperative long-term survival in trimodality therapy of malignant pleural mesothelioma: results in 183 patients. J Thorac Cardiovasc Surg 1999;117:54–63.
Received September 11, 2000; accepted November 27, 2000.
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  S. Nagata and R. Nakanishi Malignant Pleural Mesothelioma With Cavity Formation in a 16-Year-Old Boy Chest, February 1, 2005; 127(2): 655 - 657. [Full Text] [PDF]
|
|
|
|
 |
|
 H. D. Roach, G. J. Davies, R. Attanoos, M. Crane, H. Adams, and S. Phillips Asbestos: When the Dust Settles—An Imaging Review of Asbestos-related Disease RadioGraphics, October 1, 2002; 22(90001): S167 - 184. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||