Since ESOS was initially described by Wilson in 1941, approximately 300 cases have been reported thus far (5
). ESOS is defined as a malignant mesenchymal neoplasm composed of cells producing osteoid, bone and/or chondroid material, with no attachment to bone or periosteum (7
). It occurs most often in the deep soft tissues of the extremities of adults, at an average age of 50 years. Clinically, ESOS usually carries an extremely poor prognosis. The 5-year survival rate ranges from 25 to 37% for ESOS as previously reported (3
). The tumor size appears to be the only reliable prognostic variable in that tumors greater than 5 cm have a poor prognosis (3
Subcutaneous ESOS was rarely reported. Only eight cases, including the present one, were found in the literature (6
) (). Patients in those studies included 4 males and 4 females, ranging in age from 25 to 79 years. Lesions were located in the buttock in 2 cases and in the scalp, forehead, jaw, abdominal wall, lower leg and upper arm each in 1 case. In general, ESOS develops in the lower extremities, with the thigh being involved most; however, these 8 cases developed ESOS in various anatomical sites. The tumor size was less than 5 cm in all but 2 cases. A surgical resection was performed in all cases. The consequent surgical margin was wide in 7 patients, including an additional wide resection in 2 cases and an intralesional margin in 1 case. A total of three patients received chemotherapy. A wide surgical resection was performed in the present case. No chemotherapy was administered as a result of the advanced age of the patient. A wide margin is generally recommended for ESOS, as for other high-grade sarcomas (14
). Lee et al
reported that recurrence is common in ESOS and usually occurs in more than half of the patients (3
). However, a wide (or radical) resection should decrease the recurrence of ESOS.
Review of the literature describing cases of primary subcutaneous extraskeletal osteosarcoma.
The role of adjuvant chemotherapy in ESOS is unclear. A recent series (14
) found that the 5-year survival rate of patients with ESOS receiving chemotherapy showed an obvious improvement in comparison to what was described in previous reports (3
). The two most recent reports found that the 5-year survival rate of patients with chemotherapy was approximately 70% (14
). Although adjuvant therapy for ESOS remains controversial, chemotherapy may be useful in an aggressive multimodality approach to this tumor.
The 5-year survival rates associated with ESOS are relatively poor. However, 7 of the 8 cases of subcutaneous ESOS were continuously disease-free. The prognostic significance of the tumor location with respect to its relationship to the superficial fascia of the extremity or trunk was incorporated into the staging system of soft tissue sarcoma in 1998 (16
). Although only 9 patients with primary subcutaneous ESOS were previously reported in the literature, these reports may indicate that subcutaneous ESOS has a more favorable prognosis than their more deeply situated counterparts.