Massive Localized Pleural Mesothelioma Pitfalls in Preoperative Diagnosis John C. Norman, M.D.,* and Gerald D. Abrams, M.D. T he purpose of this report is to record the successful resection of a massive localized mesothelioma which originated from the visceral pleura of the right lung, replaced the right upper lobe, and compressed the right middle and lower lobes. The neoplasm produced superior vena caval obstruction, caused widening of the upper right intercostal spaces, crossed the midline, and displaced the trachea, esophagus, and mediastinal structures into the left hemithorax. Needle biopsy obtained preoperatively suggested an undifferentiated malignant neoplasm. A 60-year-old carpenter was referred to University Hospital because of an abnormal chest film. The onset of his present illness was dated approximately three to four months prior to admission, at which time he noted the gradual appearance of shortness of breath without orthopnea, nonproductive cough, and increasing fatigability. During the one to two months prior to admission, he had noted some difficulty in swallowing and a sticking sensation in the midchest. The patient had also noticed prominence of the venous channels over the right chest and arm during this interval. All other symptoms referable to the chest were denied. He had smoked approximately one-half of a package of cigarettes daily. Past, family, social, and occupational histories were not contribu tory. Physical examination revealed a thin, well-developed, 60-year-old male in no acute distress. His temperature on admission was 99 F., pulse 80 per minute, respirations 18 per minute, and blood pressure 134/70 mm. Hg. Superficial venous distention was present over the right side of the anterior chest and right arm. Bilateral neck vein distention was noted. The trachea was markedly deviated toward the left. The percussion note over the right mid- and upper chest was flat anteriorly and posteriorly. Decreased to absent breath sounds were noted over the same area, surrounded by bronchial breath sounds and absent vocal fremitus. The point of maximum cardiac impulse was 14 cm. to the left of the midsternal line in the fifth interspace and a grade 4 to 6 systolic ejection murmur was audible along the left sternal border. The remainder of the physical examination was within normal limits. The admission laboratory data included: hemoglobin, 14.7 gm./ 100 cc.; hematocrit, 44; white count, 8,100; urinalysis, negative; fasting blood sugar, From the Departments of Surgery (Section of Thoracic Surgery) and Pathology, The University of Michigan Medical Center, Ann Arbor, Mich. Supported by The Medical Foundation, Inc., Boston, Mass. Received for publication Dec. 18, 1964. Present address: Cardiovascular Section, Sears Surgical Research Laboratories, Harvard Unit, Boston City Hospital, Boston, Mass. 314 THE ANNALS OF THORACIC SURGERY
CASE REPORT: Massive Pleural Mesothelioma 91 mg.ll00 cc.; and blood urea nitrogen, 11 mg./100 cc. The electrocardiogram showed evidence of incomplete right bundle-branch block and sinus arrhythmia. Old tuberculin, coccidioidin, histoplasmin, and blastomycin skin tests were negative. The vital capacity was 57% of normal, and the maximum breathing capacity was 52% of normal. Sputa obtained for cytological examination were negative for malignant cells on three occasions. A right scalene node biopsy revealed no evidence of neoplasm. Cores of tissue obtained by percutaneous transpleural needle biopsy of the mass were interpreted as malignant neoplasm infiltrating connective tissue, which was thought possibly to represent undifferentiated carcinoma. Review of posteroanterior, stereoscopic, frontal, and lateral laminagrams, a Bucky overexposed film (Fig. 1 ), oblique esophagogram, and fluoroscopic diaphragmatic motility studies revealed a mass occupying the entire right upper hemithorax, gross displacement of the mediastinal structures far to the left, and widening of intercostal spaces on the right. There was no evidence of calcification within the mass. There was no phrenic nerve involvement. The discrete margins, excessive size, and absence of rib erosion, along with preservation of phrenic nerve function, suggested that the lesion was benign despite the percut,aneous biopsy reports. A course of radiotherapy aimed primarily at relieving the superior vena caval obstruction was undertaken. A total dose of 4,000 r was delivered to anterior and posterior right metliastinal areas for one month. Following radiation treatment, the tumor did not decrease in size. It was decided to explore the patient. At thoracotomy, the right pleural space was found to be completely obliterated. The right intrathoracic space was occupied by a bulging tumor which displaced the trachea, esophagus, and mediastinum across the midline far to the left. Extrapleural planes were developed with considerable blood loss. After a prolonged dissection, the hilar structures were encountered. The neoplasm, along with the compressed remnants of the middle and lower lobes, was removed by FIG. 1. Oblique Bucky film with nir in esophagus. VOL. I, NO. 3, MAY, 1965 315
NORMAN AND ABRAMS extrapleural pneumonectomy. The postoperative course was uneventful and the patient was discharged three weeks following operation. PA TH OLOGICA L FINDINGS The surgical specimen consisted of a right lung weighing 2900 gm. The pleural surfaces were covered by dense fibrous adhesions. The right upper lobe was replaced by a rubbery 18 X 16 X 15 cm. neoplasm with a bosselated external surface. The lower and middle lobes were compressed but not actually infiltrated by the neoplasm. No upper lobe parenchyma could be identified, and the upper lobe bronchus ended blindly in the neoplasm. It was therefore concluded that the tumor had arisen within the lobe and replaced the parenchyma completely, within the confines of the visceral pleura. The cut surface of the neoplasm (Fig. 2) was gray-white and coarsely lobulated. An irregularly whorled pattern reminiscent of that of a uterine leiomyoma was evident. Scattered foci of necrosis and cystic change were present. Hilar lymph nodes were not involved. Microscopic examination revealed the tumor to be related to the visceral pleura over broad areas. The neoplasm was composed almost entirely of fibrous connective tissue arranged in a haphazard fashion in some areas and in interlacing fascicles in others. In some sections the degree of cellularity was not marked, and dense collagenous fibers lying between delicate spindle-shaped cells dominated the field (Fig. 3). In other areas plump neoplastic cells grew in sheets with little intervening stroma. Occasionally cells were clustered in an alveolar arrangement FIG. 2. Cut surface of the neoplasm. Note the lobulations and whorling. 316 THE ANNALS OF THORACIC SURGERY
CASE REPORT: Massive Pleural Mesothetioma FIG. 3. Section from a densely fibrous area of the neoplasm. The neoplastic cells are delicate and spindle-shaped. (x 230) FIG. 4. Section from a more cellular area of the neoplasm. The component cells are plumper than those in the fibrous areas, and occasionally grow in an alveolar pattern, as in the lower left corner of the field. (X 230) around small spaces (Fig. 4). In these cellular areas, hyperchromatism and pleomorphism were frequently noted and mitoses occasionally encountered. Such areas were prominent peripherally and apparently were the areas sampled in the course of needle biopsy that gave rise to the misleading preoperative diagnosis of malignant neoplasm. When finally judged in the context of the entire specimen, these foci could not be considered indicative of unequivocal malignancy. The gross and microscopic features were considered to be those VOL. 1, NO. 3, MAY, 1965 317
NORMAN AND ABRAMS of a localized, fibrous mesothelioma, arising from the visceral pleura and replacing the right upper lobe. DISCUSSION It is now generally recognized that the lining cells of the serosal cavities can give rise to a group of distinctive but uncommon neoplasms termed mesotheliomas. Pleural mesotheliomas are usually classified on the basis of their gross appearance as either localized or diffuse, the latter being the frankly malignant form which often spreads to involve major portions of a pleural cavity. Localized pleural mesotheliomas, on the other hand, usually remain circumscribed, and may attain gigantic proportions, as occurred in the present case, without clinical evidence of infiltrative growth or distant metastases [l, 31. These neoplasms have been found projecting into the pleural cavity from either parietal or visceral pleura and, as in this case, have also been described as intrapulmonary growths springing from the visceral pleura [3]. Histologically, pleural mesotheliomas exhibit a spectrum of growth patterns including fibrous, epithelial, and mixed variants. This is considered to be a reflection of the demonstrated ability of mesothelial cells to differentiate into fibroblasts as well as epithelial elements. While diffuse mesotheliomas frequently have a prominent papillary epithelial element and solitary tumors more often a purely fibrous character, various gradations between the two have been described in both solitary and diffuse growths [3, 41. The neoplasm in the present case was categorized as a localized fibrous mesothelioma, there being but a slight suggestion of epithelial differentiation in the form of the indistinct alveolar grouping described above. The relatively good prognosis of localized as opposed to diffuse mesotheliomas of the pleura has been stressed in a number of reports [I, 2, 3, 51. Localized, often very large, tumors can be resected successfully. Following local resection, recurrence has been observed in only a few patients and distant metastases have been uncommon. It has been pointed out that the behavior of a given localized mesothelioma is difficult to predict from its histological appearance. Areas of atypism, increased cellularity and mitotic activity do not necessarily indicate a malignant potential [Z, 51. Thus, the areas of marked cellularity observed in the present case and originally sampled by needle biopsy in all likelihood do not possess the ominous significance accorded to them in the preoperative diagnosis. This case illustrates that although it may not be possible to make the specific diagnosis preoperatively, localized fibrous mesothelioma must be considered in a patient presenting with a large intrathoracic 318 THE ANNALS OF THORACIC SURGERY
CASE REPORT: Massiue Pleural Mesothelioma lesion without evidence of infiltrative or metastatic growth. Resection may be curative, even with an advanced neoplasm. S UM M A R Y A case of massive localized mesothelioma of the pleura which was resected successfully has been presented. Vagaries of cellular pattern within these neoplasms, leading to confusion in the preoperative diagnosis, are considered. The pertinent literature with respect to prognosis is reviewed. REFERENCES 1. Clagett, 0. T., McDonald, J. R., and Schmidt, H. W. mesothelioma of the pleura. J. Thorac. Surg. 24:213, 1952. Localized fibrous 2. Ehrenhaft, J. L., Sensenig, D. M., and Lawrence, M. S. Mesotheliomas of the pleura. J. Thorac. Cardiou. Surg. 40:393, 1960. 3. Foster, E. A., and Ackermann, L. V. Localized mesotheliomas of the pleura: The pathologic evaluation of 18 cases. Amer. J. Clin. Path. 34:349, 1960. 4. Godwin, M. C. Diffuse mesotbeliomas: With comment on their relation to localized fibrous mesotheliomas. Cancer 10:298, 1957. 5. Manguikian, B., and Prior, J. T. Mesotheliomas of the pleura: A clinicopathologic study of eight cases. Arch. Path. (Chicago) 75:236, 1963. VOL. 1, NO. 3, MAY, 1965 319