Mandibular osteosarcoma with unusual expression of alpha-actin smooth muscle antibody

Osteosarcoma of the jaw. The Chaim Sheba Medical Center experience

OBJECTIVE

The purpose of this article is to present 14 cases of osteosarcoma of the jaw treated at our medical center from 1989 to 1998. These cases are discussed in the light of a comprehensive review of 774 cases reported in the English literature over the past 3 decades. Differences between osteosarcoma of the jaws and osteosarcoma of the long bones are examined.

SUBJECTS AND METHODS

The patients ranged in age from 8 to 78 years, the mean age being 33 years. Each patient had a histopathologically established diagnosis of osteosarcoma of the jaw. Records were reviewed for epidemiologic data, treatment modalities, and survival.

RESULTS

Of the 14 patients, 6 (42%) had tumors in the mandible and 8 (58%) had tumors in the maxilla. Of the mandibular tumors, 5 occurred in the body of the mandible; all maxillary tumors originated in the alveolar ridge and involved the maxillary sinus. The chief complaint was an intraoral or extraoral painless swelling. Histopathologic types included chondroblastic, osteoblastic, fibroblastic, and malignant fibrous histiocytoma-like. Pathologic grade was determined to be high (3 or 4) in 13 cases and low (1) in only 1 mandibular case. All patients underwent surgical resection and immediate reconstruction. Adjuvant therapy included postoperative radiation (5 patients), postoperative chemotherapy (2 patients), and preoperative chemotherapy and postoperative radiation (1 patient).

CONCLUSIONS

The results of the present study support the literature indicating that osteosarcoma of the jaw differs from osteosarcoma of the long bones in its biological behavior even though they have the same histologic appearance. Because of differences in tumor characteristics, the introduction of chemotherapy did not dramatically alter the prognosis of osteosarcoma of the jaw. Early diagnosis and radical surgery are the keys to high survival rates.

h-Caldesmon as a specific marker for smooth muscle tumors. Comparison with other smooth muscle markers in bone tumors

Caldesmon is a protein widely distributed in smooth and non-smooth muscle cells and is thought to regulate cellular contraction. Its isoform, high-molecular-weight caldesmon (h-CD), was demonstrated to be specific for smooth muscle cells and smooth muscle tumors of the soft tissue and to never be expressed in myofibroblasts. We performed an immunohistochemical study to examine h-CD expression in the following bone tumors: conventional and non-conventional osteosarcoma, 13; malignant fibrous histiocytoma of bone, 5; giant cell tumors of bone, 5; chondroblastoma, 3; metastatic leiomyosarcoma, 2; and rhabdomyosarcoma, 1. Frequent immunoreactivity for muscle actin (alpha-smooth muscle actin or muscle-specific actin) was seen in 11 of 13 osteosarcomas and all other tumors, whereas h-CD was expressed intensely only in 2 leiomyosarcomas. h-CD is considered a specific and useful marker to distinguish smooth muscle tumor from bone tumors with myoid differentiation.