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Pseudomesotheliomatous Carcinoma of the Lung An Immunohistochemical and Ultrastructural Study of Three Cases Enrico Dessy, MD,* and Giuseppe G. Pietra, MDf The authors report immunohistochemical and electron microscopic studies on three new cases of pseudomesotheliomatous carcinoma of the lung. Although the distinct clinical and histopathologic features of this peripheral lung cancer were described many years ago, its recognition as a distinct variety of lung carcinoma has not gained wide acceptance. Little is known of its incidence and only few cases have been reported until now. In the current study the authors demonstrate the epithelial nature of this tumor by its positive immunohistochemical reactions for epithelial membrane antigen (EMA), carcinoembryonic antigen (CEA), Leu-Ml, B 72.3, and surfactant apoprotein. The ultrastructural features and staining of nuclear inclusions with surfactant apoprotein indicate differentiation into type II cells as found in other forms of peripheral lung adenocarcinoma. Despite these morphologic similarities, pseudomesotheliomatous carcinoma is characterized by extensive invasion of the pleura and rapidly fatal course. Because of this biologic behavior it deserves recognition as a distinct variant of peripheral lung carcinoma. Cancer 68:1747-1753, 1991. he term, pseudomesotheliomatous carcinoma, was In the current report we describe the results of im T coined by Harwood et al.1 to identify a distinct vari munohistochemical and ultrastructural observations in ant of peripheral lung cancer characterized by extensivethree cases of pseudomesotheliomatous carcinoma. We pleural growth and little parenchymal involvement. Be demonstrate immunohistochemical and ultrastructural cause the tumor encases the lung in a thick tumor layer features suggesting a histogenetic relationship to type II and often involves the parietal pleura, clinically, radio and Clara cell adenocarcinomas. In spite of these mor logically and macroscopically the tumor is indistinguish phologic similarities, the biologic behavior of pseudo able from malignant pleural mesothelioma.1"7 Even his- mesotheliomatous carcinoma, characterized by extensive topathologically pseudomesothelioma may be confused with malignant pleural mesothelioma because of its tubulopapillary pattern ofgrowth associated with a prominent invasion of the pleura and inconspicuous intrapulmonary growth, justifies its recognition as a distinct variant of peripheral lung adenocarcinoma. desmoplastic reaction. Previous reports have emphasized the use of histochemical techniques in the diagnosis of this neoplasm.14 5 Case Reports Two ofthe cases reported here were identified from the autopsy files of the Department of Pathology of the Hospital of the Uni From the `Institute of Pathology and Surgery, Pathologic Anatomy II, University of Cagliari Medical School, Cagliari, Italy; and the fDepartment of Pathology and Laboratory Medicine, University of Penn sylvania Medical School, Philadelphia, Pennsylvania. Supported in part by a grant from the NHLBI HL-32482. The authors thank Drs. T. Akino and G. Singh for their gifts of sur factant-apoprotein antibodies; Dr. J. Horstmann for permission to publish Case 3; M. Minda for technical assistance; and R. Krakower for secretarial help. Address for reprints: Giuseppe G. Pietra, MD, Department of Pa thology and Laboratory Medicine, University of Pennsylvania Medical School, Philadelphia, PA 19104. Accepted for publication March 19, 1991. versity of Pennsylvania (HUP, Philadelphia, PA); the third case was sent for consultation to one of the authors (G.G.P). Case l A 85-year-old man was admitted to HUP with a 3-month history of "cough after swallowing," dyspnea, and pleuritic chest pain. Pertinent findings on admission were diffuse rales, wheezes, and bilateral infiltrates on chest roentgenograms consistent with aspiration pneumonia. His past history was remarkable for 30 pack/year cigarette smoking. There was no known exposure to 1747 1748 Cancer October 15 1991 asbestos products. Bronchoscopy and bronchial washing of the left lung showed atypical epithelial cells suggestive of bronchio loalveolar carcinoma. The patient had a rapid downhill course and died 2 weeks after admission. At autopsy the lower lobe of the left lung was encased by a thick layer of gray-white tumor tissue which extended to the lower third of the parietal pleura partially obliterating the pleural space. A tumor nodule, about 4 cm in greatest dimension, was present at the base of the left lower lobe subpleurally, and was associated with dense fibrous adhesions between the base of the lower lobe and the diaphragmatic pleura. Vol. 68 Case 2 A 75-year-old man with unresectable esophageal carcinoma, treated by palliative radiation therapy and substernal gastro esophageal pull-through anastomosis, was admitted to HUP for progressive shortness ofbreath, anorexia, dysphagia, and weight loss. His past social history was remarkable for 40 pack/year cigarette tobacco use, alcoholism, and probable asbestos expo sure. On admission, chest roentgenograms revealed multiple bi lateral calcified pleural plaques on the diaphragm and lung apices, and a right lower lobe infiltrate. He developed respiratory al kalosis, leukocytosis, left vocal cord paralysis, and progressive respiratory insufficiency and died 2 days after admission. At autopsy, the major findings consisted in squamous cell carcinoma of the proximal esophagus with invasion and compression ofthe trachea. Additional findings were severe centrilobular emphysema, and multiple calcified plaques bilaterally on the diaphragmatic and parietal pleura. Over the lateral aspect of the right lower lobe, the visceral pleura was thickened by a 3-cm tumor mass which extended into the subpleural connective tissue to a depth of 5 mm. The tumor did not invade the un derlying lung tissue. The macroscopic impression at autopsy was that of a malignant pleural mesothelioma arising within a pleural plaque. Microscopic examination revealed a tubular, mucin-secreting carcinoma associated with an intense desmo plastic reaction (Fig. 1). The tumor cells were widely dissemi nated in the lymphatics of the right visceral pleura. Case 3 A 70-year-old woman was admitted to an outside hospital for palliative right pleura stripping for a malignant mesothelioma involving her right visceral and parietal pleurae. The diagnosis of mesothelioma had been established 2 months earlier during a hospitalization for recurrent right pleura effusion. There was history of possible household exposure to asbestos. At the time ofthe first hospitalization focal pleural based densities involving the anterior and posterior aspects of the right hemithorax had been seen on chest roentgenograms and computed axial tomog raphy (CAT) scan of the chest. However, no intrapulmonary masses had been detected. Bronchoscopy and bronchial biopsy were negative for malignancy. A needle biopsy of the right pleura revealed a tubulopapillary malignant epithelial tumor negative for epithelial mucin. At thoracotomy, the right pleural space contained 1400 ml of bloody fluid, and the pleura in the lower 50% of the chest and the costophrenic angle was thickened with tumor nodules. The tumor involved predominantly the parietal Fig. 1. Patient 2. Histologic appearance of pseudomesotheliomatous carcinoma. Low magnification showing the superficial spread of the neo plasm (H & E, X40). pleura but extended also the visceral pleura and the fissure be tween the middle and lower lobes. Metastatic tumor was present in the mediastinum. After pleural stripping the patient was treated with six courses of platin and mitomycin C. She did well for 19 months when reoccurrence and metastatic spread of the tumor were noticed. She received further chemotherapy with cytoxan, doxorubicin, and 5-fluorouracil (5-FU), but eventually died of widespread metastases 25 months after the original di agnosis. No autopsy was performed. Materials and Methods Histochemical and Immunohistochemical Study Histologic, histochemical, and immunohistochemical stains were performed on formalin-fixed, paraffin-em bedded tissues. Epithelial mucin was demonstrated by staining 5-/um sections with Meyer's mucicarmine or with periodic acidSchiff (PAS) before and after diastase digestion (D-PAS). Intracellular hyaluronic acid was demonstrated with col loidal iron before and after digestion with Clostridium perfringens hyaluronidase (Sigma Chemical Co., St. Louis, MO). No. 8 PSEUDOMESOTHELIOMATOUS CA OF THE Lung Dessy and Pietra 1749 The avidin-biotin complex immunoperoxidase tech nique was used for immunohistochemical studies.8 After deparaffinization, with two changes in xylene, 5-ym sec tions were hydrated using graded ethanol solutions to dis tilled water and incubated in 0.3% (v/v) hydrogen peroxide (H202) in absolute methanol for 45 minutes to quench endogenous peroxidase activity. The sections were sub sequently incubated in 20% (v/v) normal goat serum (30 minutes), followed by 1-hour incubation at room tem perature with primary antiserum, 45 minutes with sec ondary biotinylated antibody, and 45 minutes with avi din-biotin complex reagent. After each step the sections were washed repeatedly with phosphate-buffered saline (PBS, pH 7.4), and then exposed to the Chromagen re action solution (0.035% [w/v] diaminobenzidine (Sigma) in 10 ml TRIS buffer, filtered, and brought to 0.03% [w/ v] H202) for 5 minutes. After being washed in tap water the sections were counterstained in hematoxylin, dehy drated, cleared, and coverslips were applied. The sources and dilution of antibodies tested are shown in Table 1. Both negative and substitution serum controls were used. Positive tissue controls were inserted in each test. Sections were evaluated for immunoreactivity by the two authors independently. The intensity of staining of individual cells was graded on a scale of 1+ to 3+; the percentage of positive cells was recorded. Electron Microscopic Analysis Patients 2 and 3 were evaluated by electron microscopic study after fixation of fresh tissue in 1.5% (w/v) parafor maldehyde- 1.5% (w/v) glutaraldehyde in 0.1 mol/1 sodium (Na)-cacodylate buffer. In Patient 1, electron microscopic studies were performed on representative sections cut from paraffin blocks and postfixed in aldehydes.8 Samples were postfixed for 10 minutes in 1% (w/v) osmium tetroxide Table I Source and Dilution of Antibodies Reagent Source Dilution A nticarci noembryonic antigen Anti-B 72.3 Anti-leu Ml Antiepithelial membrane antigen Polyclonal antisurfactant apoproteins Monoclonal PE-10 Dako, Santa Fe, CA National Cancer Institute, Bethesda, MD Becton-Dickinson, Sunnyvale, CA Dako Dr. G. Singh, Department of Pathology, University of Pittsburgh, PA Dr. T. Akino, Department of Biochemistry, Sapporo Medical College, Sapporo, Japan 1:1250 1:5000 1:50 1:50 1:1000 1:400 Fig. 2. Patient 3. The tumor has a predominant papillary pattern (H & E, X100). (Os04) in cacodylate buffer, dehydrated in ascendinggrades of ethanol, and embedded in Poly-bed 812 (Polysciences Inc., Warrington, PA). One micron-thick sections were stained with alkaline toluidine blue for survey; selected areas were further sectioned at 60 nm for electron micro scopic study after staining with lead citrate and uranyl acetate. Results Histopathologic Findings In every case the predominant histopathologic feature was that of a tubulopapillary adenocarcinoma (Fig. 2). The tumor cells were polygonal to columnar, with abun dant cytoplasm, irregular hyperchromatic nuclei, often containing one to two prominent nucleoli. Numerous psammoma bodies were present in Patients 1 and 3. Des moplastic reaction was marked in Patients 1 and 2. In Patient 1, the glandular areas gradually blended into solid aggregates of malignant polyhedral and spindle cells, mimicking the biphasic epithelial and sarcomatous pat terns of malignant mesothelioma (Fig. 3). Epithelial mucin was demonstrated in a high percentage ofthe tumor cells with either D-PAS (Table 2) or colloidal iron. Mucicarmine gave less consistent results. Immunohistochemical Results The results of the immunohistochemical reactions are summarized in Table 2. In every case, the cytoplasm of the tumor cells was decorated with anti-CEA, EMA, LeuMi, and B 72.3. The intensity and frequency of decoration was, however, variable. In all three cases, there was finely granular decoration of the tumor cell cytoplasms with 1750 Cancer October 15 1991 Vol. 68 Fig. 4. Patient 3. Immunohistochemical staining with surfactantapoprotein antibodies showing strong decoration of nuclear inclusions (arrows) (monoclonal PE-10, X250). Fig. 3. Patient 1. The tumor is composed of nests of epithelioid and spindle cells, mimicking the biphasic features of mesothelioma (H & E, XI00). both polyclonal9 and monoclonal antisurfactant apopro tein antibodies10 (Figs. 3 and 4). In Patients 1 and 3 there was also strong decoration of intranuclear inclusions11 (Fig. 4). In Patient 1 decoration of the tumor spindle cells was more variable and only few cells were decorated. Electron Microscopic Findings The cytologic details were best preserved in Patient 3. In this case, the tumor cells lined papillary formations or microglandular structures. The tumor cells were inter connected, near their apical surface, by short desmosomes (Fig. 5). They had abundant cytoplasm containing nu merous mitochondria, electron-lucent vacuoles, and la mellar bodies of variable size (Figs. 5 and 6). The smooth and rough endoplasmic reticulum were not prominent and small bundles of cytofilaments were irregularly dis persed within the cytoplasm. The luminal surface of the tumor cells had a variable complement of microvilli which varied in size and shape, ranging from short, stubby, often branched forms to long, thin structures, with a length/ width ratio of about 10:1 (Fig. 6). In Patients 1 and 2, postmortem autolytic changes and paraffin embedding caused marked swelling and electron lucency of the matrix of the mitochondria and endoplasmic reticulum. How ever, the remaining cytoplasmic features were sufficiently preserved to identify long, thin microvilli, lamellar bodies, and intracellular microacini. Table 2. Histochemical and Immunohistochemical Features of Pseudomesotheliomatous Carcinoma Patient Age no. (yr) Sex D-PAS CEA i 85 M ++ ++ (70) (20) 2 75 M ++ ++ (20) (10) 3 70 W ++ ++ (30) (60) EMA ++ (80) +++ (100) nd Leu-M 1 +++ (80) ++ (30) +++ (80) B72.3 +++ (60) ++ (50) ++ (50) Surfactant apoproteinf Monoclonal Polyclonal ++ (100) ++ (40) ++ (60) ++ (80) ++ (30) ++ (30) D-PAS: periodic acid-Schift after diastase digestion; CEA: carcinoembryonic antigen; EMA: epithelial membrane antigen. * For each case the intensity of reaction is graded from + to +++, with the percentage of stained cells in brackets, t Positive nuclear inclusions in Patients 1 and 3. No. 8 Pseudomesotheliomatous CA OF the Lung Dessy and Pietra 1751 Fig. 5. Patient 3. Ultrastiructural aspect of the tumor cells showing acinar arrangement. The cells con tain lamellar bodies (arrows) and slender microvilli and are intercon nected by small desmosomes (orig inal magnification X4000). Discussion Harwood et ai,1 in reporting six cases of pseudome sotheliomatous carcinoma of the lung, made a convincing case for considering this entity as a distinct variant of lung cancer. The tumor is clinically, radiologically, and macroscopically indistinguishable from malignant pleural mesothelioma, and shares with the latter a rapidly fatal course. In contrast to mesothelioma, there was no appar ent causal association with exposure to asbestos or other environmental carcinogens. However, their observation has not gained wide accep tance. The entity of pseudomesotheliomatous carcinoma is briefly mentioned in current pulmonary pathology textbooks,1213 but it has not been included in the revised classifications of lung tumors by the World Health Or ganization (WHO)14 or Lung Cancer Study Group.15 Based on our experience of other cases referred for second opinion and presumed to be pleural mesotheliomas, the tumor is more common than the fifteen cases reported in the literature would lead one to believe. With the increas ing reliance on CAT scans and noninvasive diagnostic procedures, and the general decline in the number of au topsies performed on patients with cancer, it is likely that pseudomesothelioma will continue to be confused with malignant pleural mesothelioma. The correct diagnosis of pseudomesotheliomatous car cinoma of the lung is based on the recognition of distinct histopathologic features which allow its differentiation from the epithelial variant of malignant mesothelioma. A variety of histochemical and immunohistochemical methods have been proposed to help in the differential diagnosis between pleural malignant mesothelioma and pleural metastases of adenocarcinoma.716-19 We have found, as have others,7 that immunohistochemical reac tions, particularly the positive reaction for CEA, Leu-M 1 and B 72.3, are useful in distinguishing pseudomesothe liomatous carcinoma from mesothelioma. The results of the current study suggest that the immunohistochemical demonstration of surfactant apoprotein in tumor cells20 invading the pleura, may be of further help in differen tiating metastases of lung carcinoma from metastases of extrapulmonary malignancies. Others have emphasized the diagnostic importance of electron microscopic study21'22 and the length:width ratio of microvilli in the diagnosis of malignant mesothelioma.7'22 23 We have found that the lengthrwidth ratio of microvilli, by itself, is not a reliable diagnostic feature to distinguish meso- 1752 Cancer October 15 1991 Vol. 68 Fig. 6. Patient 3. Higher magni fication shows slender microvilli and small desmosomes (arrows) and la mellar bodies (original magnification X30,000). thelioma from pseudomesothelioma, since the latter may also show long microvilli. The immunohistochemical demonstration of surfactant apoprotein in nuclear inclusions and the ultrastructural features of lamellar bodies suggest a derivation of this tumor from type II cells or Clara cells. Because of its marked desmoplastic reaction, a relation to the so-called "scar carcinoma" has been proposed.4 In recent years it has become apparent that assumptions as to the histo genesis of a lung neoplasm should not be made solely on the basis of morphologic features. The mere fact that a neoplasm shows features of type II cells or Clara cells does not warrant the conclusion that these cells have dediffer entiated to become neoplastic. During the development of cancer there may be activation of repressed genes that regulate differentiation, leading to the transformation of columnar epithelial cells into highly specialized cells, like type II and Clara cells. In spite to its similarity to bronchioloalveolar and other peripheral lung papillary carcinomas composed of type II pneumocytes and Clara cells, pseudomesotheliomatous carcinoma has a markedly dissimilar biologic behavior. Because of the extensive pleural involvement, its prognosis is poor. In the reported cases, the average survival, from onset of symptoms, was 4.2 months (range, 0.8 to 9 months). In our own material, the first patient died a few months after the onset of symptoms; in the second patient the tumor was discovered at autopsy. The third patient died of widespread metastases in approximately 2 years after diagnosis. Further studies are needed to determine whether the aggressive behavior is due to intrinsic invasive properties of the tumor cells or to the unique location of the tumor in close proximity to the vast pleura lymphatic network. REFERENCES 1. Harwood TR, Gracey DR, Yokoo H. Pseudomesotheliomatous carcinoma of the lung: A variant of peripheral lung cancer. Am J Clin Pathol 1976; 65:159-167. 2. Braganza JM, Blanche Butler E, el al. Ectopic production of salivary type amylase by a pseudomesotheliomatous carcinoma of the lung. Can cer 1978; 41:1522-1525. 3. Broghamer WL Jr, Collins WM, Mojsejenko IK. The cytohistopathology of a pseudomesotheliomatous carcinoma of the lung. Acta Cytol 1978; 22:239-242. 4. Lin Jl, Tseng CH, TsungSH. Pseudomesotheliomatous carcinoma of the lung. South Med J 1980; 73:655-657. 5. Nishimoto Y, Ohno T, Saito K. Pseudomesotheliomatous carci noma of the lung with histochemical and immunohistochemical study. Acta Pathol Jpn 1983;33:415-423. 6. Simonsen J. Pseudomesotheliomatous carcinoma of the lung with asbestos exposure. Am J Forensic Med Pathol 1986; 7:49-51. 7. Wick MR, Loy T, Mills SE, Legier JF, Manivel JC. Malignant No. 8 Pseudomesotheliomatous CA of the Lung Z>mp and Pietra 1753 epithelioid pleural mesothelioma versus peripheral pulmonary adeno carcinoma: A histochemical, ultrastructural, and immunohistologic study of 103 cases. Hum Pathol 1990; 21:759-766. 8. Brooks JSJ, LiVolsi VA, Pietra GG. Mesothelial cell inclusions in mediastinal lymph nodes mimicking metastatic carcinoma. Am J din Pathol 1990; 93:741-748. 9. Singh G, Katyal SL, Torikata C. Carcinoma of type II pneumocytes: Immuno-diagnosis of a subtype of "bronchiolo-alveolar carcinomas.'' Am J Pathol 1981; 102:195-208. 10. Kuroki Y, Fukada Y, Takahashi H, Akino T. Monoclonal anti bodies against human pulmonary surfactant apoproteins: Specificity and application in immunoassay. Biochim Biophys Acta 1985; 836:201-209. 11. Singh G, Scheithauer BW. Katyal SL. The pathologic features of carcinomas oftype II pneumocytes: An immunocytologic study. Cancer 1986; 57:994-999. 12. Churg A. Diseases of the pleura. In: Thurlbeck WM, ed. Pathology of the Lung. Stuttgart, New York: Thieme Med. Publ., 1987; 769-802. 13. Hammar SP, Bolen .JW. Pleural neoplasms. In: Dail DH, Hammar SP, eds. Pulmonary Pathology. New York, Berlin, Heidelberg, London, Paris, Tokyo: Springer Verlag, 1988; 973-1028. 14. World Health Organization. Histological typing of lung tumors. Tumori 1981;67:253-272. 15. Mountain OF, Lukeman JM, Hammar SP et al. Lung cancer classification: The relationship of disease extent and cell type to survival and clinical trials population. J Surg Oncol 1987; 35:147-156. 16. Battifora H, Kopinski MI. Distinction of mesothelioma from ad enocarcinoma: An immunohistochemical approach. Cancer 1985; 55: 1679-1685. 17. Mullink H, Henzen-Logmans SC, Alons-van Kordelaar JJM, Tadema TM, Meijer CJLM. Simultaneous immunoenzyme staining of vimentin and cytokeratins with monoclonal antibodies as an aid in the differential diagnosis of malignant mesothelioma from pulmonary ad enocarcinoma. Virchows Arch [Cell Pathol] 1986; 52:55-65. 18. Dewar A, Valente M, Ring NP, Corrin B. Pleural mesothelioma of epithelial type and pulmonary adenocarcinoma: An ultrastructural and cytochemical comparison. J Pathol 1987; 152:309-316. 19. Ordonez NG. The immunohistochemical diagnosis of mesothe lioma. Am J Surg Pathol 1989; 13:276-291. 20. Mizutani Y, Nakajima T, Morinaga S et al. Immunohistochemical localization of pulmonary surfactant apoproteins in various lung tumors: Special reference to nonmucus producing lung adenocarcinomas. Cancer 1988; 61:532-537. 21. Wang NS. Electron microscopy in the diagnosis of pleural me sotheliomas. Cancer 1973; 31:1046-- 1054. 22. Warhol MJ, Hickey WF, Corson JM. Malignant mesothelioma: Ultrastructural distinction from adenocarcinoma. Am J Surg Pathol 1982; 6:307-314. 23. Warhol MJ, Corson JM. An ultrastructural comparison of me sotheliomas with adenocarcinomas of the lung and breast. Hum Pathol 1985; 16:50-55.