AJR 2000; 175:887
© American Roentgen Ray Society
Musculoskeletal Case of the Day |
Case 1
Extraskeletal Osteosarcoma
Joseph S. Yu,
Carol J. Ashman and
Marcella Dardani
The findings in this case include a large soft-tissue mass
(Fig. 1A) in the right side of
the abdomen associated with dense ossification and calcification in the
inferior aspect of the mass. The right psoas shadow is absent. The CT scan
(Fig. 1B) shows that the mass
does indeed arise from the right psoas muscle and is heterogeneous in density,
with central areas of low attenuation.
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Fig. 1A. —60-year-old man who presented with vague abdominal pain and palpable
abdominal mass. Frontal radiograph of abdomen shows obliteration of right
psoas shadow by large space-occupying process in peritoneal cavity
(arrows). Note several dense areas in mass.
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Fig. 1B. —60-year-old man who presented with vague abdominal pain and palpable
abdominal mass. CT scan shows large soft-tissue mass of heterogeneous
attenuation arising from right psoas muscle. Note two areas of
ossification.
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Extraskeletal osteosarcomas are rare
[1]. Reported estimates suggest
that fewer than 4% of osteogenic sarcomas are of this subtype
[2,
3]. The neoplasms are located
in the soft tissues and do not have an osseous or periosteal attachment.
Pathologically, these tumors possess a uniform sarcomatous pattern and an
osteoid or cartilaginous matrix
[4]. Some investigators have
hypothesized that extraskeletal osteosarcoma may arise from a previous focus
of myositis ossificans. The highest incidence is in the fifth decade of life.
The most common presentation is a mass; however, when in the abdomen or
pelvis, these tumors may reach enormous sizes before detection. About 75% of
extraskeletal osteosarcomas develop in the lower extremity, particularly in
the thigh
[2,3,4,5].
The upper extremity accounts for about 15-23% of cases
[1]. The prognosis is poor,
with a 5-year survival rate of less than 25%. Treatment is aimed at resection.
Adjuvant chemotherapy or radiation therapy remains controversial
[3].
The differential diagnosis includes extraskeletal chondrosarcoma, malignant
fibrous histiocytoma, rhabdomyosarcoma, and hamartoma.
The other possible diagnoses were incorrect for various reasons. Myositis
ossificans would not be associated with a large soft-tissue mass. Although a
synovial sarcoma is associated with a soft-tissue mass and calcifications, it
does not occur in the peritoneum. The typical calcifications that occur in a
hemangioma are phleboliths. Calcifications associated with hydatid disease are
either peripheral (cystic hydatid disease) or central (alveolar hydatid
disease).
References
-
Cook PA, Murphy MS, Innis PC, Yu JS. Extraskeletal osteosarcoma of
the hand. J Bone Joint Surg
1998;80-A:725
-729[Free Full Text]
-
Lee JS, Fetsch JF. Wasdhal DA. Lee BP, Pritchard DJ, Nascimento AG.
A review of 40 patients with extraskeletal osteosarcoma.
Cancer
1995;76:2253
-2259[Medline]
-
Sordillo PP, Hajdu SI, Magill GB, Golbey RB. Extraosseous
osteogenic sarcoma: a review of 48 patients. Cancer
1983;51:724
-734
-
Bane BL, Evans HL, Ro JY, et al. Extraskeletal osteosarcoma: a
clinicopathologic review of 26 cases. Cancer
1990;65:2762
-2770[Medline]
-
Patel SR, Benjamin RS. Primary extraskeletal osteosarcoma:
experience with chemotherapy. J Natl Cancer Inst
1995;87:1331
-1333[Free Full Text]
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