Osteosarcomas rarely occur in the hand12. This primary neoplasm of bone may be classified, on the basis of its origin, as central, juxtacortical, or extraskeletal. Extraskeletal osteosarcomas are extremely rare and, although their true prevalence is unknown, it has been estimated that they account for approximately one in twenty-five (twenty-six of 6501) reported cases of primary osteosarcoma of bone.
Extraskeletal osteosarcomas are located in the soft tissues without skeletal or periosteal attachment, and they have a uniform sarcomatous pattern and a matrix composed of osteoid or cartilage, or both. In contradistinction to primary osteosarcoma of bone, this variant typically develops after the fourth decade of life1 and the prognosis is uniformly poor1,2,4,5,8,9,11,14,15.
In the present report, we document the clinical and pathological findings in a patient who had an extraskeletal osteosarcoma arising from the thenar muscles of the hand.
*No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. No funds were received in support of this study.
†Hand and Microsurgery Associates, 3400 Olentangy River Road, Columbus, Ohio 43202.
‡Raymond M. Curtis Hand Center, National Center for Treatment of the Hand and Upper Extremity, Union Memorial Hospital, 201 East University Parkway, Baltimore, Maryland 21218. Please address requests for reprints to Dr. Murphy.
§Division of Musculoskeletal Imaging, Department of Radiology, Ohio State University Medical Center, 410 West Tenth Avenue, Columbus, Ohio 43210.
A sixty-three-year-old man was referred to the Raymond M. Curtis Hand Center because of a rapidly enlarging, painless mass in the left hand. The patient had noticed the mass five months earlier, after sustaining a minor injury to the hand. He had had no recent health problems and recalled no family history of cancer.
Physical examination confirmed the presence of a firm, immobile mass situated deep in the first web space of the left hand. The mass was approximately five by five by six centimeters and filled the first web space. Radiographs of the left hand demonstrated a soft-tissue mass with a central ossific matrix contained within the thenar eminence; the mass did not appear to be attached to the underlying skeleton (Figs. 1-A and 1-B). Magnetic resonance images showed a large soft-tissue mass with heterogeneous signal intensity within the thenar muscles (Figs. 2-A, 2-B, and 2-C). Peritumoral edema was evident, and the ossific matrix was seen as a region of heterogeneous low signal intensity.
The results of preoperative laboratory studies were normal. The hemoglobin was 168 grams per liter (normal range, 132 to 172 grams per liter), the hematocrit was 49.3 per cent (normal range, 41 to 50 per cent), the level of alkaline phosphatase was eighty-two units per liter (normal range, zero to 250 units per liter), the level of serum calcium was 9.6 milligrams per deciliter (2.40 millimoles per liter) (normal range, 8.5 to 10.3 milligrams per deciliter [2.12 to 2.57 millimoles per liter]), the level of serum phosphate was 3.8 milligrams per deciliter (1.23 millimoles per liter) (normal range, 2.5 to 4.5 milligrams per deciliter [0.81 to 1.45 millimoles per liter]), and the erythrocyte sedimentation rate was four millimeters per hour (normal range, zero to eighteen millimeters per hour). Imaging studies performed for staging, including radiography and computerized tomography of the chest and abdomen, demonstrated normal findings.
Open biopsy was performed, and a tan mass with a firm consistency and an ossified central core was seen. Histological evaluation of the specimen demonstrated numerous neoplastic cells producing osteoid and cartilage, consistent with a high-grade osteoblastic osteosarcoma (Fig. 3). According to the system of the Musculoskeletal Tumor Society7, the tumor was a high-grade intracompartmental sarcoma (stage II-A).
One week after the open biopsy, a below-the-elbow amputation was performed, leaving twenty centimeters of the proximal part of the forearm intact. The gross pathological findings confirmed an encapsulated mass, 5.5 by five by five centimeters, within the adductor pollicis muscle. The mass did not involve the remaining thenar muscles or extend to the adjacent skeleton. The margins of the specimen were free of disease.
Eighteen months after the amputation, the patient had no evidence of local recurrence in the left upper extremity, but radiographs of the chest showed widespread metastatic disease of the lungs (Fig. 4). The patient, who refused additional intervention, was alive two years after the amputation.
Review of the Literature
Extraskeletal osteosarcomas are extremely rare. Characteristically, these tumors present as a mass in the soft tissues without any skeletal or periosteal attachment. Histological findings include a uniform sarcomatous pattern with neoplastic cells producing osteoid or cartilage, or both1. Unlike primary osteosarcoma, which commonly develops before the age of twenty-five years, the extraskeletal variant usually develops during the fifth or sixth decade of life1,2,4,5,8,9,11,14,15, ages that are similar to that of our patient. However, similar to primary osteosarcoma of the hand11, extraskeletal osteosarcoma can develop at ages ranging from the first to ninth decades of life1,2,11,13,15.
Location of the Lesion
Most extraskeletal osteosarcomas develop in the lower extremity, with the thigh being involved most often2,11,13,15, but the tumor can involve other anatomical locations, such as the large muscles of the pelvis and shoulder. In most large series, the prevalence of lesions in the upper extremity has ranged from 15 per cent (six of forty extraskeletal tumors) to 23 per cent (eleven of forty-eight)1,2,10,11,15. A total of twenty-seven primary extraskeletal lesions were found in the upper extremity in these series, with twelve (44 per cent) involving the shoulder, eleven (41 per cent) involving the proximal part of the extremity, two (7 per cent) involving the hand, one (4 per cent) involving the forearm, and one involving the wrist.
Management of Our Patient
Wide resection and limb-salvage was an option for our patient because of the intracompartmental location of the tumor. However, resection of this tumor, which was five centimeters or larger, in all dimensions, would have necessitated ablation of the rays of the thumb and the index, middle, and ring fingers to achieve an adequate margin; only the small finger would have been preserved. Also, an osteocutaneous flap (either pedicled or free) and a toe-to-hand composite-tissue transfer would have been necessary to restore useful function of the hand. Nerve regeneration is not optimum in older patients, and sensibility of the transferred digit might not have been restored. In addition, our patient had a history of coronary artery disease and had been managed with coronary artery bypass grafting twice. These factors, combined with the patient's request to have the least number of operative procedures possible, led us to recommend a below-the-elbow amputation (a radical resection). The patient quickly adapted to the below-the-elbow prosthesis and was able to perform bimanual activities of daily living six weeks after the procedure. Although the course of treatment resulted in local control of the tumor, it did not prevent metastatic disease.
Alternative options consist of adjuvant radiation therapy or chemotherapy, or both (that is, therapy that is given after excision of the tumor) or neoadjuvant radiation therapy or chemotherapy (therapy given before excision and sometimes continuing after excision) combined with a limb-salvage operation. Adjuvant chemotherapy for extraskeletal2 and intraskeletal10 osteosarcoma has not been shown to improve the survival of older patients and has been associated with increased toxicity3,10 and poor tolerance to treatment16. A limb-salvage procedure, combined with microvascular transfer of tissue, warrants consideration when a treatment plan is being formulated. The results of some studies have suggested that adjuvant radiation treatment or chemotherapy, or neoadjuvant chemotherapy, increases survival2,13, but additional research is necessary.
Role of Adjuvant Therapy
The role of adjuvant chemotherapy or radiation therapy, or both, in the treatment of extraskeletal osteosarcoma is unclear. In a recent series11, chemotherapy or radiation therapy, or both, was used when the patient had a large lesion, a marginal excision, or a local recurrence or it was used as palliative treatment. There was local recurrence in one of four patients who had had adjuvant treatment compared with three of eleven patients who had not, and distant metastasis occurred in four of seven patients who had had adjuvant treatment compared with seven of eleven patients who had not11. Bane et al. demonstrated a temporary response to chemotherapy. However, other investigators have found little benefit of radiation therapy or chemotherapy for the prevention of local recurrence or distant metastasis1,14,15. Despite these discouraging findings, the use of adjuvant treatment should not be abandoned until the results of a standard protocol of chemotherapy or radiation therapy, or both, have been evaluated in a multicenter study. Currently, the results of neoadjuvant chemotherapy for extraskeletal osteosarcoma do not parallel those for intraskeletal osteosarcoma; the response of extraskeletal osteosarcoma is similar to that of malignant fibrous histiocytoma2. Future research involving neoadjuvant chemotherapy13 may expand the indications for limb-salvage procedures.
Prognosis
Generally, the five-year survival rates associated with extraskeletal osteosarcoma have been poor1,2,6,8,9,11,13-15: 24 per cent (eleven of forty-five) in the study by Sordillo et al., 31 per cent (eight of twenty-six) in the study by Bane et al., and 38 per cent (fifteen of thirty-nine) in the study by Lee et al. Most patients have local recurrence2,11,15 or distant metastasis, or both. The lung is the most common site of metastasis2,11,13,15. The size of the tumor at the time of intervention seems to be an important prognostic factor, with lesions smaller than five centimeters associated with longer disease-free survival2,11. Survival rates have also been better after wide or radical resection11,14,15. Limb salvage is optimum when function of the distal end of the limb and sensibility can be preserved. Microvascular composite-tissue transfer may be instrumental in achieving closure of the wound. Wide resection would have preserved only the small finger in our patient. Staged composite-tissue transfer (transfer of an osteocutaneous flap from the groin or transfer of the great or second toe) would have provided a post for opposition. We discussed this option with the patient but did not recommend it because we did not believe that the sensibility of the transferred tissue would be adequate.