P53 expression as a prognostic marker in giant cell tumor of bone: a pilot study.

P53 is the best known tumor suppressor gene. If p53 is mutated, the ability of the cell to sense and repair DNA defects is lost. Failure of this mechanism increases the risk of malignant transformation and tumorigenesis. P53 overexpression is implicated in many carcinomas. P53 alterations appear to be frequent in bone and soft tissue sarcoma and have a strong negative impact on survival in various subtypes of sarcoma like Ewing's sarcoma, synovial sarcoma, and myxoid liposarcoma. There is also evidence in the literature that p53 may be implicated in bone giant cell tumor behavior. The goal of this pilot retrospective study was to detect p53 mutation in giant cell tumor of bone and correlate it with clinical outcome. We analyzed the presence of p53 mutation in 39 patients with giant cell tumor of bone by means of immunohistochemical staining; 8 tumors expressed mutated p53 protein. Seven of them recurred locally (P<.001) and 2 metastasized to the lung (P<.05). In multivariate analysis/subgroup analysis, local recurrence was still strongly correlated, while metastasis had a weaker correlation. Our findings suggest that p53 mutation in giant cell tumor of bone can be useful in predicting tumor behavior, especially in regard to local recurrence. Limitations of this study include the retrospective data collection, the limited number of patients, and the multifactorial nature of the disease; tumor grade, surgical margins, use of adjuvant therapy, and thoroughness of excision may influence the therapeutic outcome. Despite these limitations, this correlation should be further investigated with larger clinical studies. P53 may be used as a marker for the biologic behavior of giant cell tumor of bone.

Plexiform schwannoma of the posterior tibial nerve: a case report.

INTRODUCTION: Plexiform schwannoma is one of the least common variants of schwannoma. It is usually found on the trunk, head, neck and upper extremities. Most reported cases are small tumors, less than 2cm in maximum diameter, arising from superficial nerves. Trauma and neurofibromatosis type 2 are well-recognized risk factors for plexiform schwannoma. It is important to differentiate it from plexiform neurofibroma, because the former has neither an association with von Recklinghausen's disease nor a malignant potential. CASE PRESENTATION: We report a case of a large plexiform schwannoma arising from the posterior tibial nerve in proximity with the medial malleolus. The patient had no history of ankle strain, fracture or neurofibromatosis type 2. Magnetic resonance imaging demonstrated a multinodular, inhomogeneous lesion, measuring 6 x 4 x 2.8 cm. Fine needle biopsy was suggestive of a benign lesion, deriving from neural elements. The mass was excised marginally. Permanent section showed that the lesion was multilobular, surrounded by a thin fibrous capsule and consisting of elongated cells, rare typical mitosis, cells with degenerative features and stained positive for S-100 protein. The patient was not evident disease at the latest follow-up 2.3 years later, with an excellent functional result. No sensory or motor deficits were encountered. CONCLUSION: There are no reports in the literature for large plexiform schwannomas arising from the tibial nerve. Marginal excision seems to be the recommended therapy for this rare tumor.

Detection of somatostatin receptors in human osteosarcoma.

BACKGROUND: The location of osteosarcoma in the metaphysis as well as the age of the patients during the most rapid tumour growth suggest that factors related to skeletal growth are involved in the pathogenesis of this tumour. In this aspect this study aims to detect somatostatin receptors in human osteosarcomas and correlate this finding with the clinical outcome of the tumour. PATIENTS AND METHODS: Immunohistochemical staining for the presence of somatostatin receptors as well as overall survival and disease free survival rates were retrospectively studied in twenty-nine osteosarcoma patients. RESULTS: Four osteosarcomas with several aggressive biologic behaviour expressed somatostatin receptors. In these four young patients the event free rate was 0% and the overall survival rate was 50% at 4, 3 years. In contrast the event free survival rate of the twenty-five patients with negative somatostatin receptor status was 72% with an overall survival rate of 76% at 4,3 years. CONCLUSION: The present study demonstrates the existence of somatostatin receptors in human osteosarcoma. Tumours expressing somatostatin receptors seemed to be aggressive with a very low disease free and overall survival rate compared to osteosarcoma with negative receptor status.

The role of imatinib mesylate in adjuvant therapy of extra-abdominal desmoid tumors.

BACKGROUND: Extra-abdominal desmoid tumors are rare neoplasms with variable biological behavior. The mainstay of treatment is surgery. Complementary treatment with tyrosine-kinase receptor inhibitor drugs, particularly imatinib mesylate, has been reported in the literature. The purpose of this study was to determine the possible presence of tyrosine-kinase receptors in extra-abdominal desmoid tumors as a marker for imatinib mesylate therapy. PATIENTS AND METHODS: From 1999 to 2004, immunohistochemical methods were carried-out in 14 patients with histologically confirmed extra-abdominal desmoid tumors to determine c-KIT positivity (existence of tyrosine-kinase receptors and PDGFRA and PDGFRB). RESULTS: All desmoid tumors were c-KIT negative, which demonstrates absence of tyrosine-kinase receptors. CONCLUSION: The histological c-KIT markup is an easy and reliable method that can detect whether a desmoid tumor is sensitive to additional treatment with a tyrosine-kinase receptor inhibitor. Molecular biological analysis for the identification of KIT and PDGFR mutation should be performed before imatinib mesylate is included in any treatment protocol.