Parosteal lipoma is a rare and generally asymptomatic benign tumor of mature adipose tissue that is located in direct apposition to the external surface of the bone. These tumors are occasionally associated with reactive changes in the underlying bone. The reactive bone formation is generally restricted to the base of the tumor, that is, near the periosteum. We recently experienced a case of parosteal lipoma in the proximal femur, which displayed exuberant bone and cartilage formation, and this led us to a misdiagnosis of chondroblastic osteosarcoma on the initial biopsy. We report here on this case with a special emphasis on making the differential diagnosis from osteosarcoma.
Adipose Tissue ; Biopsy ; Cartilage ; Chondrocytes ; Diagnosis, Differential ; Diagnostic Errors ; Femur* ; Lipoma* ; Osteogenesis ; Osteosarcoma ; Osteosarcoma, Juxtacortical ; Periosteum

osteosarcoma is a distinct entity of malignant bone tumor with characteristic clinical, morphological, and histological features within the group of juxtacortical osteosarcoma. Periosteal osteosarcoma is predominantly located in the tubular long bones, and extremely rarely involving the jaws. A case of periosteal osteosarcoma of the right mandible is presented. A 27-year-old woman complained of the gingival swelling and bleeding tendency of the right posterior mandible. Clinical examination revealed a reddish brown strawberry-like swelling on the affected mucosa, which measured 1.5cm X 1.5cm. The tumor was located on the lingual cortex of the mandible and extended into the surrounding soft tissues. Microscopically, the tumor consisted exclusively of atypical chondroblastic cells with a small osteoblastic area. A minimal bone marrow involvement was noted and the adjacent cortex was free of tumor. These findings suggested that the tumor originated from the periosteal cambium layer, which lies between the periosteal fibrous layer and the cortex of mandible.]]>
Adult ; Bone Marrow ; Cambium ; Chondrocytes ; Female ; Hemorrhage ; Humans ; Jaw ; Mandible ; Mucous Membrane ; Osteoblasts ; Osteosarcoma ; Osteosarcoma, Juxtacortical

39-year-old female had been treated for the exophytic mass on buccal aspect of the left maxillary posterior area 2 years and 8 months ago. Tentative diagnosis was obtained as fibrous dysplasia on clinical and radiographic examinations and histopathologic findings revealed as osteochondroma after bone trimming at that time. She revisited for the treatment of recurred lesions. We reviewed this case with clinical, radiologic and histopathologic standpoints retrospectively, and came to a conclusion that the tumor primarily occurred was juxtacortical osteogenic sarcoma and recurred due to inadequate treatment and then expanded over intramedullary. This case shows that the diagnosis of osteosarcoma should take account of the patient history, clinical, radiographic and histopathologic findings and it requires attentive follow up check. Retrospectively reviewed results were as follows ; At first visit, oral examination revealed a bony hard swelling on the buccal aspect of the left maxillary posterior area. Radiographically, a dense radiopaque mass was noted on the site. The lesion showed hot uptake of 99mTc-MDP. Histopathologic diagnosis was done as osteochondroma, but it was considered as osteogenic sarcoma when compared with the recurrent lesion. When she revisited for the treatment of multiple bony swelling on the left maxilla, radiograms showed typical features of malignancy such as widening of periodontal ligament space and sun-ray appearace, and coincided with benign characters as follows ; relatively well circumscribed lesion and expansion and displacement of the adjacent structures. Finally, histopathologic findings of the lesion was well differentiated chondroblastic osteogenic sarcoma.
Adult ; Chondrocytes* ; Diagnosis ; Diagnosis, Oral ; Female ; Follow-Up Studies ; Humans ; Maxilla* ; Osteochondroma ; Osteosarcoma* ; Osteosarcoma, Juxtacortical ; Periodontal Ligament ; Retrospective Studies ; Technetium Tc 99m Medronate

OBJECTIVETo investigate the way of diagnosis and therapy of parosteal osteosarcoma.

METHODSA retrospective review was conducted of 48 patients treated at our department between June 1964 and December 2001. The average age of patients in this study was 29.2 years (13 - 47 years). Thirty-two of the patients were female; sixteen were male. The single most common site is the posterior aspect of the distal femur (in 36 patients), followed by the femur shaft (in 6 patients), the proximal tibia (in 2 patients), etc. Nine patients had been operated on before referral to our department.

RESULTSThe average follow-up period from the first operation was 5.2 (0.25 - 24) years. In 36 of the 39 patients in whom a limb-salvage procedure was performed, a segment of the tumor-bearing bone was excised along with the tumor, whereas in 3 patients only the subadjacent cortex was excised with the tumor. In the limb-sparing group, the reconstruction was achieved by means of attenuated tumor bone or allograft in 23 cases, by endoprosthetic replacement in 9 cases, and by allograft replacement in 4 cases. The local resections were wide in 35 cases, and marginal in 13 cases. After marginal surgery, local recurrence occurred in 5/13 patients, whereas it occurred in 3/35 patients treated with wide resection. Pulmonary metastases developed in 6 patients, four patients died, and 2 patients are alive with disease. There were 4 cases of fractures of bone grafts. Four patients developed an infection. Long-term survival rate is 85.8%. For tumors that invaded the medullary canal there was no statistical association with local recurrence or metastasis. There is statistical significance between surgical margin and local recurrence.

CONCLUSIONSWide surgical excision alone is adequate treatment for patients with conventional parosteal osteosarcoma. A tumor-free margin remains the critical factor determining overall prognosis. When a marginal excision was knowingly done to preserve a major neurovascular bundle, the risk of recurrence was less than when it was done to shell-out a presumptively benign lesion. Repeated recurrence probably increases the risk of dedifferentiation and thereby worsens the prognosis. Recurrent lesions with multiple soft-tissue satellite nodules or involvement of the neurovascular structures may however require amputation to provide sufficient local control when a wide margin cannot be achieved. An individualized resection will be performed in the future probably under the help of the advanced technique of image to distinguish the reactive zone from the normal tissue precisely.

Adolescent ; Adult ; Bone Neoplasms ; diagnostic imaging ; surgery ; Female ; Humans ; Male ; Middle Aged ; Neoplasm Recurrence, Local ; Osteosarcoma, Juxtacortical ; diagnostic imaging ; surgery ; Prognosis ; Radiography

Parosteal osteosarcoma (POS) is the most common form of surface osteosarcoma. Its symptoms are insidious and its duration prior to diagnosis is considerably longer than that of other types of osteosarcoma. We report a case of POS with a growing mass but no evidence of metastasis. This tumor, which was diagnosed as calcified hematoma with benign characteristics, was incompletely resected in our hospital 21 years before the diagnosis of recurrence. The patient underwent a wide en bloc resection in our hospital and was free of symptoms, with no signs of tumor recurrence or metastasis during a 53-month follow-up.
Adult ; Bone Neoplasms ; diagnosis ; pathology ; surgery ; Diagnostic Errors ; Follow-Up Studies ; Humans ; Humerus ; Magnetic Resonance Imaging ; Male ; Neoplasm Recurrence, Local ; Osteosarcoma, Juxtacortical ; diagnosis ; pathology ; surgery ; Radiopharmaceuticals ; Technetium Tc 99m Medronate ; Tomography, Emission-Computed ; Tomography, X-Ray Computed