[Giant cell-rich lesions of bone and their differential diagnosis]. / Obrovskobunecné léze kostí a jejich diferenciální diagnostika.

Giant cell-rich lesions form a heterogeneous group of reactive and truly neoplastic processes with diverse clinical presentation and biological behavior. Common to all of them are variably numerous multinucleated osteoclast-like giant cells and the presence of mononuclear stroma. Based on the histological picture alone it is sometimes impossible to reliably distinguish certain tumors from each other. The pathologist has to know the patient´s age, the exact localization, tumor growth dynamics and its radiographic characteristics. Secondary reactive changes occur frequently and these can completely alter the morphology of the lesion and thus overshadow the underlying neoplasm. Reparative changes in a pathological fracture may histologically mimic primary bone malignancy. Immunohistochemistry helps only in select cases and molecular genetic methods still have very limited utility for the diagnosis of giant cell-rich tumors. It is necessary to correlate the microscopic features of the lesion with clinical and radiological findings. A correct diagnosis is of paramount importance for proper treatment and prognosis.

Vertebral giant cell tumour of bone in a domestic shorthair cat.

Case summary: A 10-year-old male neutered domestic shorthair cat was presented with a 5-month history of progressive non-ambulatory paraparesis. Initial vertebral column radiographs revealed an L2-L3 expansile osteolytic lesion. Spinal MRI showed a well-demarcated, compressive expansile extradural mass lesion affecting the caudal lamina, caudal articular processes and right pedicle of the second lumbar vertebra. The mass was hypointense/isointense on T2-weighted images, isointense on T1-weighted images and had mild homogeneous contrast enhancement after gadolinium administration. MRI of the remaining neuroaxis and CT of the neck, thorax and abdomen with ioversol contrast revealed no additional neoplastic foci. The lesion was removed by en bloc resection via a dorsal L2-L3 laminectomy, including the articular process joints and pedicles. Vertebral stabilisation was performed with titanium screws placed within L1, L2, L3 and L4 pedicles with polymethylmethacrylate cement embedding. Histopathology revealed an osteoproductive neoplasm composed of spindle and multinucleated giant cells without detectable cellular atypia or mitotic activity. On immunohistochemical evaluation, osterix, ionised calcium-binding adaptor molecule 1 and vimentin labelling were observed. Based on the clinical and histological features, a giant cell tumour of bone was considered most likely. Follow-up at 3 and 24 weeks postoperatively demonstrated significant neurological improvement. Postoperative full-body CT at 6 months showed instability of the stabilisation construct but absence of local recurrence or metastasis. Relevance and novel information: This is the first reported case of a giant cell tumour of bone in the vertebra of a cat. We present the imaging findings, surgical treatment, histopathology, immunohistochemistry and outcome of this rare neoplasm.

Spinal giant cell-rich osteosarcoma-diagnostic dilemma and treatment strategy: A case report.

BACKGROUND: Giant cell-rich osteosarcoma (GCRO) is a rare histological variant of osteosarcoma. Spinal GCROs are extremely rare, with challenging diagnosis and management. Herein, we present a case of spinal GCRO at T2, which was not diagnosed in initial biopsy but after T2 corpectomy. We detailed the clinical course, management strategy, and outcome after a 4-year follow-up. CASE SUMMARY: A 17-year-old female patient presented with back pain followed by ascending paresthesia. Spinal computed tomography (CT) and magnetic resonance imaging (MRI) revealed a collapsed T2 vertebra with an enhancing osteolytic mass. CT-guided biopsy showed inconclusive morphology. Pathology from T2 corpectomy revealed GCRO. The patient subsequently received neoadjuvant chemotherapy followed by salvage operation of T2 costotransversectomy with grossly-total resection adjuvant chemoradiation. Upon treatment completion, she had complete GCRO remission. The 4-year follow-up spinal MRI showed no tumor recurrence. CONCLUSION: Spinal GCRO poses unique challenges in obtaining sufficient tissue diagnosis and complete surgical removal. However, long-term local control of spinal GCRO is possible following complete resection and adjuvant chemoradiation.

Giant cell rich osteosarcoma revisited-diagnostic criteria and histopathologic patterns, Ki67, CDK4, and MDM2 expression, changes in response to bisphosphonate and denosumab treatment.

Defining giant cell-rich osteosarcoma (GCRO) as "an osteosarcoma in which more than 50% of the tumor consists of numerous uniformly distributed osteoclastic giant cells amidst oval or spindle mononuclear cells embedded in a fibrovascular stroma," eight such cases identified among 265 cases of osteosarcoma were analysed. Their age ranges from 11 to 33 years, with peak incidence in the second decade and equal sex distribution. Seventy-five percent presented with pain, commonest in the knee, affecting the metaphysis. Most appeared radiologically as well-circumscribed expansile multiloculated osteolytic lesions, and many are displayed periosteal reaction. They showed several distinct histologic patterns: the stromal and giant cell, fibrohistiocytic, aneurysmal-cystic, osteoblastoma-like, and parosteal and fibrous dysplasia-like patterns. Focal subtle lacelike osteoid deposition, permeative infiltration into adjacent native bony trabeculae and over 30 % Ki67 proliferative index were characteristic. There was no CDK4 and MDM2 amplification. In those having bisphosphonate and denosumab treatment, there was limited focal necrosis with reduction in the number of giant cells and broad trabecular woven bone formation but no giant osteoclast was seen. Two patients with initial diagnosis of giant cell tumor treated by curettage and local resection pursued aggressive clinical courses, died after 14 and 21 months. The others survived 12 to 110 months. GCRO accounts for about 3 % of all osteosarcomas and apart from its more frequent diaphyseal location and associated normal bone-specific alkaline phosphate levels; it shares with conventional high-grade osteosarcoma the same patient demographics, sites of occurrence, absence of CDK4 and MDM2 amplification, and probably clinical course.

Giant cell-rich osteosarcoma of the parotid gland: An exceptionally rare entity at an unusual site.

Giant cell-rich osteosarcoma is a rare histologic variant of conventional osteosarcoma that affects mainly the extremities. Extraskeletal giant cell-rich osteosarcoma is therefore exceedingly rare. Here, we report the first case of this uncommon tumor involving the parotid gland in a 62-year-old male who presented with initial right jaw swelling. Radiologic work-up revealed a 6.2 cm mass involving the right parotid gland. Fine-needle aspiration cytology showed numerous multinucleated giant cells in a background of dyshesive epithelioid cells and rare clusters of spindle stromal cells, suspicious for malignancy. The subsequent excisional biopsy showed histopathologic features diagnostic for giant cell-rich osteosarcoma. Diagn. Cytopathol. 2016;44:1107-1111. © 2016 Wiley Periodicals, Inc.

Primary Osteosarcoma of the Skull Base Treated with Endoscopic Endonasal Approach: A Case Report and Literature Review.

Introduction Giant cell-rich osteosarcoma (GCRO) is a rare pathologic diagnosis, and most cases have involved the appendicular skeleton. We present a challenging diagnosis of GCRO of the skull base treated with an endoscopic endonasal approach. Case Presentation An 18-year-old female patient presented with acute monocular visual loss. Imaging revealed a large clival mass encasing the internal carotid arteries bilaterally with pituitary and optic nerve compression. The lesion was resected via a staged endoscopic endonasal approach and the patient's vision normalized postoperatively. The final pathological diagnosis was challenging and, after consultation with multiple North American centers, was concluded as GCRO. The tumor recurred and further surgery was performed, followed by adjuvant chemoradiation. Conclusion We highlight diagnostic challenges of GCRO of the skull base, and describe, with intraoperative pictures, successful surgical resection via an endoscopic endonasal approach. Based on our literature review, this is the first published case report of GCRO of the skull base.

Giant cell rich osteosarcoma of the mandible with abundant spindle cells and osteoclast-like giant cells mimicking malignancy in giant cell tumor.

Giant cell rich osteosarcoma is a relatively unusual histological form of osteosarcoma, common lesion usually presenting in the long bones of the appendicular skeleton. The occurrence in the mandible is exceptional rare. Histologically, this tumor tends to be a highly anaplastic, pleomorphic tumor in which the tumor cells may be: plasmacytoid, fusiform, ovoid, small round cells, clear cells, mono-or multinucleated giant cells, or, spindle cells. Herein, we present a case with the sternum and first thoracic vertebra metastasis from primary giant cell rich osteosarcoma of the mandible in a 28 year-old Chinese female. The tumor was predominantly composed of abundant spindle cells with marked atypia and numerous osteoclast-like giant cells reminiscent of malignancy in giant cell tumor. The unusual histological appearance can pose a great diagnostic challenge. It may be easily misdiagnosed, especially if the specimen is limited or from fine-needle aspiration.

Fibular giant cell-rich osteosarcoma virtually indistinguishable radiographically and histopathologically from giant cell tumor-analysis of subtle differentiating features.

Giant cell-rich osteosarcoma by its abundance of osteoclastic giant cells and paucity of tumor osteoid, leads to its easy confusion with giant cell tumor during biopsy interpretation. In this report, we describe a unique case of upper fibular metaphyseal giant cell-rich osteosarcoma in a 12-year-old boy; the radiographic and histopathologic features of the biopsy and initial resected tumor are virtually indistinguishable from conventional giant cell tumor. The tumor rapidly recurred 7 months after resection with metastasis to the groin lymph nodes, was resistant to first-line chemotherapy and pursued an aggressive course, developing disseminated metastasis to the lung, liver, pelvis, scapula and clavicle, and resulted in the death of the patient 21 months after initial presentation. The subtle features alerting one to the possibility of giant cell-rich osteosarcoma are retrospectively evaluated in comparison with cases of metaphyseal conventional giant cell tumors, four from our records and those from literature review. We conclude that the occurrence of a giant cell-rich lesion in the metaphysis of a skeletally immature individual merits careful assessment for the presence of periosteal reaction, permeative infiltrative margins, lacelike osteoid formation, high mitotic activity or Ki67 proliferative index, and extra-tumoral lymphovascular permeation, since the possibility of an aggressive lesion notably giant cell-rich osteosarcoma probably increases with the number of such features.

Epiphyseal osteosarcoma revisited: four illustrative cases with unusual histopathology and literature review.

Osteosarcomas arising in the epiphysis are extremely rare and easily missed in the diagnostic consideration of epiphyseal tumors. It is the purpose of this study to delineate the clinical pathological characteristics of 'epiphyseal osteosarcoma' under the definition of 'a solitary long bone osteosarcoma radiographically considered an epiphyseal tumor for which the main radiologic differential diagnosis would encompass giant cell tumor, chondroblastoma and clear cell chondrosarcoma'. Four such cases with unusual histopathology were retrieved among 110 cases of osteosarcoma. Their clinical, radiological and pathological features, together with all 10 reported cases, were analyzed. The radiographic diagnoses of our four cases include two giant cell tumors, one chondroblastoma and one clear cell chondrosarcoma but turn out to be fibroblastic, giant cell rich, telangiectatic and epithelioid variant of epiphyseal osteosarcoma. Including our patients, the 14 reported epiphyseal osteosarcomas comprise 8 males and 6 females, the age at presentation ranges from 11 to 39 years, two-third in the second decade, 71.4% affect the femur. Due to their epiphyseal locations, many carry benign radiological diagnoses notably giant cell tumor and chondroblastoma. Epiphyseal osteosarcomas may not only masquerade as benign radiological bony lesions but also assume many histological patterns; orthopedic surgeons, radiologists and pathologists should be aware of such possibility. Their behavior and prognosis are dictated by the histologic types, grading and staging rather than location.