1/3. Two unusual osteogenic orbital tumors: presumed parosteal osteosarcomas of the orbit.OBJECTIVE: To report two cases of suspected parosteal osteosarcoma of the orbit, with dedifferentiation into a high-grade liposarcoma occurring in one patient. DESIGN: Two retrospective case reports. methods: The clinical, radiologic, and pathologic records of two patients with suspected orbital parosteal osteosarcoma were retrospectively reviewed. MAIN OUTCOME MEASURES: Histologic evaluation and clinical follow-up were measured. RESULTS: The first patient was a 47-year-old male presenting with a 5-month history of painless right lower lid swelling; excision biopsy suggested a well-differentiated parosteal osteosarcoma of the orbital floor, which recurred 3 years later. Six months after excision of the recurrence, the mass demonstrated accelerated growth, and a lid-sparing exenteration was performed; histologic examination showed a high-grade liposarcoma. The patient remains disease-free at 4 years. The second patient, a 40-year-old male, presented with an 8-year history of proptosis and a right superotemporal orbital mass. The mass was excised completely at lateral orbitotomy; histologic examination suggested a well-differentiated parosteal osteosarcoma. The patient remains well 9 months postoperatively. CONCLUSIONS: Parosteal osteosarcoma is an uncommon tumor, usually affecting long bones, that is extremely rare in the orbit. It is a low-grade sarcoma that tends to recur locally after excision but has a favorable prognosis. Dedifferentiation into a high-grade sarcoma occasionally occurs in parosteal osteosarcoma, but transformation into liposarcoma does not seem to have been previously reported. It is important to recognize dedifferentiated parosteal osteosarcoma, because the prognosis is poor, and radical treatment may be required.- - - - - - - - - - ranking = 1keywords = dedifferentiated (Clic here for more details about this article) |
2/3. The role of imaging modalities in the diagnosis of primary dedifferentiated parosteal osteosarcoma.Dedifferentiated parosteal osteosarcoma (dd-POS) is defined as high-grade sarcomatous components coexisting with low-grade POS components. With regard to the histological diagnosis of dd-POS, the sampling of a small area of dedifferentiation through the densely mineralized POS can be a problem. In this situation, imaging is important to identify the area with the highest possibility of dedifferentiation. We report a patient in whom dedifferentiation was shown by computed tomography (CT) and magnetic resonance imaging (MRI). CT revealed a radiolucency in a highly mineralized area. T2-Weighted MRI showed a relatively high signal intensity, corresponding to the radiolucency, surrounded by a very low signal intensity area. Furthermore, gadolinium-enhanced T1-weighted MRI showed marked enhancement. Based on these imaging techniques, the condition was diagnosed as most likely to be a dd-POS, although a representative sample was not accessible by incisional biopsy. Neoadjuvant chemotherapy was administered, followed by wide resection and adjuvant chemotherapy. Four years after the surgery, partial lobulectomy was required because of a pulmonary metastasis. Three years after the second surgery, the patient remained well without evidence of metastases. Based on the initial diagnosis and, consequently, the optimal treatment of combined chemotherapy and wide resection, our patient showed a good clinical outcome.- - - - - - - - - - ranking = 4keywords = dedifferentiated (Clic here for more details about this article) |
3/3. Juxtacortical dedifferentiated chondrosarcoma from a primary periosteal chondrosarcoma.In this report, we describe dedifferentiation in a primary periosteal chondrosarcoma in the proximal tibia of a 73-year-old man. The diagnosis of primary periosteal chondrosarcoma was made by the characteristic radiographic, gross, and microscopic features of the tumor. The presence of dedifferentiation, however, in the form of malignant fibrous histiocytoma, was an unexpected histologic finding. Although rare, dedifferentiation is a well-recognized occurrence in secondary chondrosarcomas arising from precursor osteochondromas. This event has not been previously documented in the setting of primary periosteal chondrosarcoma.- - - - - - - - - - ranking = 4keywords = dedifferentiated (Clic here for more details about this article) |