Reliability and Role of Mutation-specific H3F3A (Histone 3-3) G34W Immunohistochemistry to Differentiate Giant Cell Tumor of Bone From its Clinicoradiologic and Histologic Mimics: An Institutional Study.

Giant cell tumor of bone (GCTB) is a benign neoplasm, which can sometimes be a diagnostic challenge, especially in small biopsies, due to its histologic benign and malignant mimics. We evaluated the role of H3.3 G34W immunohistochemistry (IHC) antibody in diagnosing GCTB and its role in differentiating it from its close histologic mimics. A total of 120 cases (80 cases of GCTB and 40 cases of histologic mimics) were retrieved and subjected to IHC. Of 80 cases of GCTB, 72 cases showed a positive nuclear immunoexpression, while all 40 cases of histologic mimics of GCTB showed a negative staining for H3.3 G34W IHC. Sensitivity and specificity of this mutation-specific antibody for diagnosis of GCTB was 90% and 100%, respectively, while, the positive predictive value and the negative predictive value were 100% and 83.3%, respectively. A positive expression of H3.3 G34W was seen in all 5 cases of GCTB, postdenosumab therapy, as well as, in all 3 cases of malignant giant cell tumor. The presented study showed that H3.3 G34W mutation-specific IHC is a reliable and specific marker for GCTB and can help distinguish it from the histologic mimics due to distinct therapeutic implications.

Comparison of the diagnostic performances of core needle biopsy in myxoid versus non-myxoid tumors.

BACKGROUND: Despite the overall diagnostic utility of core needle biopsy (CNB) comparable to incisional biopsy, increased diagnostic errors have been suggested of CNB for myxoid soft tissue tumors. This study compared the diagnostic performance of CNB between myxoid and non-myxoid soft tissue tumors. METHODS: 369 patients who underwent ultrasound-guided CNB prior to resection for soft tissue tumors were classified into two groups according to resection pathology; myxoid group (n = 75) and non-myxoid group (n = 294). One-hundred and ninety-three patients were male and the median age of the patients was 40 years. Two-hundred and sixty-three tumors were malignant. RESULTS: CNB correctly diagnosed malignancy in 84% (58 of 69) for the myxoid group and 95% (184 of 194) for the non-myxoid group. For diagnosing histologic grade of soft tissue sarcoma, CNB correctly identified high grade in 78% (18 of 23) for the myxoid group and 74% (94 of 128) for the non-myxoid group. Correct diagnosis rate of histological type was significantly lower in the myxoid group (63% [47 of 75] in the myxoid group and 83% [242 of 294] in the non-myxoid group, p = 0.013). CONCLUSION: Our study suggests that CNB is useful for myxoid soft tissue tumors of the extremity, with regard to diagnosing malignancy and histologic grade. However, CNB was less useful for identifying histologic subtype in myxoid tumors than in non-myxoid tumors.

Vascularized fibula with and without extracorporeal radiotherapy for limb salvage surgery in Indian patients.

BACKGROUND: Reconstruction of segmental bone defects following resection of bone sarcomas is a challenging procedure. Vascularised fibula grafts alone or in combination with extracorporeal radiotherapy and reimplantation of tumor bone have long been established as a method of reconstruction of such defects, with satisfying results. Prompted by paucity of data on Indian patients, we report our experience with vascularised fibula graft for patients undergoing limb salvage surgery for sarcomas of bone. MATERIAL AND METHODS: A total of 25 patients underwent the procedure from December 2008 to December 2014. Femur was the commonest site and osteosarcoma was the commonest diagnosis. Intercalary resection was done in 19 patients and arthrodesis in 6 patients. Vascularised fibula was used in combination with extra corporeally irradiated bone in eight patients, and alone in 17 patients. RESULTS: All but one limb could be salvaged, and all but three patients had united at final follow up. Combination of extracorporeal radiotherapy and reimplantation with vascularised fibula fared better than vascularised fibula alone in terms of time to union (9.6 months vs 12.2 months) and rate of graft related complications (14.2% vs 62.5%). CONCLUSION: Reconstruction with VFG with or without ECRT has a good and predictable functional outcome. Though manageable with active intervention, complications were more commonly seen with vascularised fibula alone than a combination of the two techniques.