CASE REPORTS Ex traosseous 0s teogenic Sarcoma of the Pleura Lawrence Cohn, M.D., and Albert D. Hall, M.D. T he spontaneous appearance of an osteogenic tumor in soft tissues is a rare but well-documented pathological entity [4, 81. Although these tumors arise predominantly in the soft tissues of the extremities, the following case is the first to be reported in which this tumor spontaneously originated from the pleura. This case is presented to alert the thoracic surgeon to the possible occurrence of this unusual tumor in the parietal pleura. A 61-year-old white man entered the Fort Miley Veterans Hospital on April 21, 1967, because of pleuritic pain in the left upper chest and a cough which had increased in severity during the past 9 months. Three weeks before admission, he had hemoptysis; an x-ray of the chest showed extensive infiltration in the left upper lobe and a small pleural effusion (Fig. 1). He had never smoked, and had not been exposed to tuberculosis or fungi. He had no history of chest trauma or radiation therapy to the thorax or mediastinum. He had lost 25 pounds during the past several months. The blood pressure was 150/90 mm. Hg; the pulse was 106 and regular, and the temperature was 101'F. There was percussive and auscultatory evidence of consolidation in the left upper anterolateral chest. Laboratory examinations showed only a mild elevation of fasting blood sugar. Left thoracic laminagraphy revealed a large mass, probably originating in the intrathoracic soft tissues, separated from the overlying bony structures and without evidence of bone destruction (Fig. 2). Bronchoscopy, biopsy of a left scalene lymph node, cytology examination of pleural fluid, and complete metastaric bone survey were negative. Exploratory thoracotomy was performed through a left fourth interspace incision 4 weeks after admission. A large necrotic tumor of the left anterolateral pleural surface, unattached to the overlying bony structures, was found. The tumor had invaded the adjacent pulmonary parenchyma, and several metastatic nodules were found in the lung. The tumor was considered to be nonresectable, and after a biopsy the thorax was closed. The postoperative course was un- From the Departments of Surgery, University of California Medical Center, and Veterans Administration Hospital, San Francisco, Calif. Accepted for publication Dec. 28, 1967. VOL. 5, NO. 6, JUNE, 1968 545
COHN AND HALL A FIG. 1. P-A (A) and lateral (B) x-rays of the chest taken on admission showing an extensive neoplastic mass in the left upper lobe and a small left pleural eflusion. eventful except for slight atelectasis. A complete bone survey after operation did not reveal a primary bone tumor, Pathological examination of the biopsy specimen showed extraosseous osteogenic sarcoma, arising primarily in the pleura, with typical osteoid formation and highly malignant, pleomorphic cellular stroma, characteristic of this tumor (Fig. 3). A strontium*z bone scan of the thorax and mediastinum demonstrated rapid bone growth only in the region of the tumor. The patient died shortly thereafter from bilateral bronchopneumonia. Postmortem examination showed findings similar to those at operation, although the tumor now occupied almost all of the left hemithorax except for the atelectatic basal segments of the lower lobe. Metastatic lesions were found in the left lung, pleura, pericardium, and the right kidney. No primary osseous B FIG. 2. A portion of a laminagram of the left side of the chest which shows that the overlying ribs are not involved. 546 THE ANNALS OF THORACIG SURGERY
CASE REPORT: Osteogenic Pleural Sarcoma A FIG. 3. (A) Biopsy specimen shown under low-power magnification ( ~10 x 3.5). (B) Biopsy specimen shown under medium-power magnification (xl0 x 4.3). The specimens demonstrate pleomorphic spindle-shaped tumor cells. The nuclei are hyperchromatic, and numerous mitotic figures and multinucleated giant cells are seen. The tumor cells are forming neoplastic cartilage and bone. The nonosseous stroma is sarcomatous and contains a moderate amount of vasculature. There are areas of necrosis throughout. (Congo red stain was positive in foci that contained osteoid.) tumor could be found. Postmortem x-ray of the chest wall overlying the tumor again demonstrated that the tumor did not involve the rib cage. B DISCUSSION Of the approximately 60 cases of extraosseous osteogenic sarcoma that have been reported, over 90% have been located in the extremities 14, 81. Only 12 such tumors were found in the records of over 150,000 surgical specimens that were reviewed by Fine and Stout [4]. Rarely, truncal tissue has been involved in this malignancy, including the soft tissues of the jaw [5], neck [7], abdominal wall [lo], mesentery [9], the meninges [12], the esophagus of the dog [3], and thyroid gland [Z]. In addition, the development of osteogenic sarcoma in soft tissue after extensive radiation therapy is well recognized [l]. The occurrence of this tumor in the thoracic cavity or surrounding structures is extremely unusual. Stauss [ll] published the first report of an osteogenic sarcoma arising in the pleura in a patient with traumatic hemothorax and hematoma of the chest wall. Kauffman and Stout [8] reported extraskeletal chondrosarcoma in the thoracic wall in a 2-year-old child who died after multiple resections. Finally, Hoff- VOL. 5, NO. 6, JUNE, 1968 547
COHN AND HALL mann et al. [6] published the case of a 59-year-old man with a tumor of the left latissimus dorsi muscle which presented as a left thoracic-wall tumor. This primary osteogenic sarcoma was resected, and a metastatic lesion from this primary tumor was also resected from the contralateral lung. Our case is the first report of osteogenic sarcoma in the pleura which apparently was of spontaneous origin. Though intensive efforts both preoperatively and postmortem were made to rule out an osteogenic sarcoma arising in bone, it is still conceivable that a very occult bone tumor might be responsible for the pleural lesion; however, we consider it extremely unlikely. Calcification in soft tissue occurs commonly in hematomas (myositis ossificans), blood vessels, cardiac structures, and occasionally in healing wounds, which indicates the potentiality of the fibroblast in soft tissue to form calcific material under the proper stimulus. When one considers the spontaneous appearance of a primary osteogenic neoplasm, the theory of metaplasia, a change from one cell type to another, must be invoked. In this instance, the pluripotential mesenchymal cell redifferentiates to osteoblasts which lay down bone in response to some unknown environmental stimulus. This change to a malignant cell type represents a rare aberrancy of this common fibroblastic response. The true osteogenic sarcoma may be differentiated from the pseudomalignant soft-tissue bone tumors and atypical forms of myositis ossificans by the presence of blood-vessel invasion by the tumor cells, and by the absence of a true capsule on gross and microscopic examination [4]. The soft-tissue osteogenic sarcoma that arises after irradiation therapy appears to be identical to the spontaneous form, both histologically and clinically [ 11. These tumors have very poor prognosis because of their tendency toward early metastasis and rapid, widespread local growth. Treatment consists of wide local excision if metastases have not already developed. Radiation therapy is of no value. Although this tumor rarely arises in the thoracic cavity, it should be considered in the differential diagnosis of pleural tumors. Its association with chest trauma and postradiation therapy of the thorax makes it of additional importance to the thoracic surgeon. SUMMARY The first patient to be reported with spontaneous extraosseous osteogenic sarcoma of the pleura is presented. Bone surveys, chest laminagraphy, and premortem and postmortem x-rays of the overlying rib were negative. The histological appearance was identical to osteogenic sarcoma arising in bone. This rare pathological entity occurs primarily in other soft tissues, and its differentiation from pseudomalignant and extraosseous bone tumors is discussed. 548 THE ANNALS OF THORACIC SURGERY
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