Oncogenic osteomalacia (OO) is a rare paraneoplastic syndrome of osteomalacia due to phosphate wasting. The phosphaturic mesenchymal tumor (mixed connective tissue variant) (PMTMCT) is an extremely rare, distinctive tumor that is frequently associated with OO. Despite its association with OO, many PMTMCTs go unrecognized because they are erroneously diagnosed as other mesenchymal tumors. Expression of fibroblast growth factor-23 (FGF-23), a recently described protein putatively implicated in renal tubular phosphate loss, has been shown in a small number of mesenchymal tumors with known OO. The clinicopathological features of 32 mesenchymal tumors either with known OO (29) or with features suggestive of PMTMCT (3) were studied. Immunohistochemistry for cytokeratin, S-100, actin, desmin, CD34, and FGF-23 was performed. The patients (13 male, 19 female) ranged from 9 to 80 years in age (median 53 years). A long history of OO was common. The cases had been originally diagnosed as PMTMCT (15), hemangiopericytoma (HPC) (3), osteosarcoma (3), giant cell tumor (2), and other (9). The tumors occurred in a variety of soft tissue (21) and bone sites (11) and ranged from 1.7 to 14 cm. Twenty-four cases were classic PMTMCT with low cellularity, myxoid change, bland spindled cells, distinctive "grungy" calcified matrix, fat, HPC-like vessels, microcysts, hemorrhage, osteoclasts, and an incomplete rim of membranous ossification. Four of these benign-appearing PMTMCTs contained osteoid-like matrix. Three other PMTMCTs were hypercellular and cytologically atypical and were considered malignant. The 3 cases without known OO were histologically identical to the typical PMTMCT. Four cases did not resemble PMTMCT: 2 sinonasal HPC, 1 conventional HPC, and 1 sclerosing osteosarcoma. Three cases expressed actin; all other markers were negative. Expression of FGF-23 was seen in 17 of 21 cases by immunohistochemistry and in 2 of 2 cases by RT-PCR. Follow-up (25 cases, 6-348 months) indicated the following: 21 alive with no evidence of disease and with normal serum chemistry, 4 alive with disease (1 malignant PMTMCT with lung metastases). We conclude that most cases of mesenchymal tumor-associated OO, both in the present series and in the reported literature, are due to PMTMCT. Improved recognition of their histologic spectrum, including the presence of bone or osteoid-like matrix in otherwise typical cases and the existence of malignant forms, should allow distinction from other mesenchymal tumors. Recognition of PMTMCT is critical, as complete resection cures intractable OO. Immunohistochemistry and RT-PCR for FGF-23 confirm the role of this protein in PMTMCT-associated OO.

The addition of high-dose ifosfamide to methotrexate, cisplatin, and doxorubicin in the preoperative phase is feasible, but with major renal and hematologic toxicities, and survival rates similar to those obtained with four-drug regimens using standard-dose ifosfamide. Italian Sarcoma Group/Scandinavian Sarcoma Group study I showed that in a multicenter setting, more than 90% of patients with osteosarcoma of the extremity can undergo conservative surgery.

If confirmed on larger series, selective arterial embolization seems to be the first treatment option for spine aneurysmal bone cyst, because of the low cost-to-benefit ratio. Diagnosis must be certain, based on pathognomonic radiographic pattern or on histologic study.- In case of neurologic involvement, pathologic fracture, technical impossibility of performing embolization, or local recurrence after at least two embolization procedures, complete intralesional excision would be the therapy of choice.

RFI, site of metastases, and number of pulmonary nodules are the main prognostic factors for PRS in osteosarcoma. Complete surgery of recurrence is pivotal in the strategy of treatment. Patients with unresectable recurrence benefit from second-line chemotherapy, whereas our data do not support a generalized use of chemotherapy after complete surgery of first recurrence.

With an aggressive neoadjuvant chemotherapy, it is possible to cure more than 60% of patients with nonmetastatic osteosarcoma of the extremity and amputation may be avoided in more than 80% of them. Because local or systemic relapses, myocardiopathies, and second malignancies are possible even 5 years or more after the beginning of treatment, a long-term follow-up is recommended for these patients.

BACKGROUNDThe term malignant giant cell tumor embraces multiple entities and therefore can be confusing. The goals of the current study were to define the clinicopathologic and histologic features of malignancy in giant cell tumors and to clarify the terminology.METHODSThe authors reviewed all cases from the Rizzoli Institute (Bologna, Italy) of primary (PMGCT) and secondary (SMGCT) malignancy in giant cell tumors. PMGCT is a high‐grade sarcoma that arises side by side with benign giant cell tumors. SMGCT is a high‐grade sarcoma that occurs at the sites of previously treated giant cell tumors of bone.RESULTSThe authors report 5 PMGCTs and 12 SMGCTs; half of the SMGCTs were postradiation sarcomas. Patient age ranged from 20 to 68 years (median, 62 years) for PMGCT and from 30 to 77 years (median, 40 years) for SMGCT. The average latent period between diagnosis of giant cell tumor and diagnosis of SMGCT was 9 years (range, 3–15 years) for patients with postradiation SMGCT and 19 years (range, 7–28 years) for patients with SMGCT resulting from spontaneous transformation. The histologic classification of high‐grade sarcomas in the PMGCT group was osteosarcoma in four cases and malignant fibrous histiocytoma in one case. In the SMGCT group, the histologic classification was osteosarcoma in nine cases, fibrosarcoma in two cases, and malignant fibrous histiocytoma in one case. The outcomes associated with all malignancies in giant cell tumors were poor, with the worst outcome associated with postradiation SMGCT.CONCLUSIONSMalignancies in giant cell tumors of bone always are high‐grade sarcomas with a poor prognosis. These lesions must be distinguished from benign giant cell tumors of bone. SMGCT usually is easy to diagnose upon malignant clinicoradiographic presentation. In contrast, PMGCT often mimics giant cell tumors both clinically and radiographically. In addition, upon histologic examination, PMGCT shows areas of conventional giant cell tumor, which can lead to difficulties in making the correct diagnosis. Cancer 2003;97:2520–9. © 2003 American Cancer Society.DOI 10.1002/cncr.11359

In patients with high-grade osteosarcoma treated with surgery and chemotherapy, the presence of increased levels of P-glycoprotein in tumor cells is associated with a significantly increased risk of adverse events and is independent of the extent of necrosis after preoperative chemotherapy.

The prognosis in cases of nonmetastatic Ewing's sarcoma is influenced by many different clinical and hematologic variables, all of which are to be considered when patients are being stratified according to the risk of relapse. In surgically treated patients, the most important prognostic factor is chemotherapy-induced necrosis.