Osteolysis in a cementless, second generation metal-on-metal hip replacement.

A 65-year-old man with osteoarthritis of the hip underwent a cementless total hip replacement with a modern generation, metal-on-metal bearing. Two years later the patient presented with localized osteolysis at the tip of the femoral stem. At the time of revision, the stem was found to be well-fixed. Extensive analyses of the bearing surfaces and periprosthetic tissues were done. There was minimal bearing surface wear and only small numbers of inflammatory cells, such as macrophages, in the tissues, and it was concluded that this was not a typical case of particle-induced osteolysis. All cultures and laboratory studies were negative for infection. This case report supports the multifactorial nature of osteolysis, which includes the osteolytic potential of joint fluid access to and fluid pressures within, the effective joint space.

Giant notochordal hamartoma of intraosseous origin: a newly reported benign entity to be distinguished from chordoma. Report of two cases.

Two cases are reported of a newly described intraosseous entity of vertebral bodies deemed "giant notochordal hamartoma of intraosseous origin". This entity is commonly mistaken for chordoma and must be distinguished from it as the consequences of misinterpretation may be serious. The clinical, radiological and histologic criteria that can be used to distinguish these two entities are emphasized. Included is a proposed pathogenesis for this lesion, its probable notochordal origin, and a review of other probable cases.

Viability of femoral heads treated with resurfacing arthroplasty.

There is a general conception that resurfacing arthroplasty causes femoral head osteonecrosis and subsequent failure of the implant. This study histologically analyzed 25 resurfaced femoral heads up to 12 years postoperatively and found that osteonecrosis was not induced by the procedure.

Intraosseous glomus tumor of the fibula.

Glomus tumor is a rare, benign vascular tumor and intraosseous glomus tumor, which arises primarily within bone, is even rarer. Fewer than 20 cases have been reported in the literature. We present the case of a 34-year-old woman with glomus tumor primarily in the midshaft of the fibula that radiologically mimicked chondromyxoid fibroma, aneurysmal bone cyst or adamantinoma, together with a review of other reported cases.

Expression of tau proteins and tubulin in extraskeletal myxoid chondrosarcoma, chordoma, and other chondroid tumors.

Tau proteins are microtubule-associated proteins required for the polymerization of tubulin. The abnormal accumulation of tau proteins in neurofibrillary tangles is a well-known phenomenon and has been studied extensively. However, the role of tau protein in chondroid tissue and its neoplasia is unknown. In the present study, 2 extraskeletal myxoid chondrosarcomas (EMCs), 6 chordomas, 6 chondrosarcomas, 3 myxoid chondrosarcomas of bone, 2 osteochondromas, 6 chondroblastomas, and 2 nonneoplastic adult articular cartilages were immunostained with monoclonal antibodies against tau proteins and tubulin. The results showed that the coexpression of tau proteins and tubulin was present only in EMCs (2/2) and chordomas (4/6). Although tubulin was detected in chondroblastomas (5/6), osteochondromas (2/2), chondrosarcomas (5/6), and myxoid-chondrosarcomas of bone (3/3), tau expression was absent in these tumors. The perichondrial chondroblasts but not chondrocytes from nonneoplastic articular cartilage also localize tau and tubulin with a much weaker staining intensity. The results mainly demonstrate that there is frequent expression of tau proteins in some microtubule-rich neoplasms, such as EMC and chordoma. The different immunostaining pattern of tau proteins between chordoma and myxoid chondrosarcoma of bone may be useful in the differential diagnosis, especially when both neoplasms occur in the base of skull.

Benign and malignant cartilage tumors of bone and joint: their anatomic and theoretical basis with an emphasis on radiology, pathology and clinical biology. II. Juxtacortical cartilage tumors.

In part I, we reviewed the varied clinical presentations, pathogenesis, histologic findings, radiologic findings, and treatment of intramedullary cartilaginous lesions of bone. In this section, we will evaluate our cases and consultations of juxtacortical cartilaginous tumors. Radiographic differential diagnosis includes the numerous juxtacortical lesions particularly osteochondroma, parosteal chondroma, Trevor's disease, trauma (fracture and periostitis ossificans), and the low- and high-grade surface osteosarcomas. By emphasizing pathogenesis in conjunction with radiographic and histologic findings, pitfalls in diagnosis and subsequent treatment can be avoided in such cases.

Pseudoanaplastic giant cell tumor of bone.

Marked nuclear atypia can be found in a variety of benign mesenchymal tumors, including ancient schwannomas, symplastic leiomyomas, osteoblastomas, and chondromyxoid fibromas. Such nuclear atypia is believed to represent a degenerative phenomenon and does not indicate aggressive behavior. Separation of these pleomorphic but benign lesions from true sarcomas may be difficult. We are aware of only one prior description of such degenerative atypia in benign giant cell tumor of bone. We report a benign giant cell tumor of bone arising in the sacrum of a 21-year-old white female. Preoperative embolization of this lesion had been performed, and subsequent curetting revealed marked atypia suggestive of an anaplastic malignancy. However, only very rare mitotic figures were present, and the radiographs were consistent with a benign giant cell tumor. A diagnosis of benign giant cell tumor was made, and no recurrence or metastases have been observed during the 4-year postoperative period.

Pseudoanaplastic chondromyxoid fibroma.

A 19-year-old man presented with a chondromyxoid fibroma of the distal phalanx of the great toe that was originally diagnosed as osteosarcoma rather than "dedifferentiated" chondrosarcoma. Radiographs showed a large, expansive, and calcified tumor of the distal phalanx. Although the tumor had the architectural and matrix patterns of a chondromyxoid fibroma, high-power examination demonstrated that the lesion had such severe nuclear pleomorphism that it was mistaken for high-grade sarcoma. The purpose of this report is to present the criteria used to differentiate a benign pseudoanaplastic chondromyxoid fibroma from chondrogenic high-grade sarcomas.

Osteochondromalike parosteal osteosarcoma: a report of six cases of a new entity.

OBJECTIVE: Our purpose was to describe a rare juxtacortical bone sarcoma with deceptively benign, osteochondromalike histologic characteristics. We present criteria by which this low-grade malignant neoplasm can be distinguished from other benign and malignant surface lesions of bone with particular emphasis on the imaging features. MATERIALS AND METHODS: Six cases of a low-grade, chondroossifying parosteal sarcoma of bone were reviewed. Patients included four males and two females 11 months to 66 years old. Histologic findings from initial tumors and from recurrent tumors were reviewed. Two musculoskeletal radiologists analyzed the imaging studies, which included plain films, CT scans, MR images, and a bone scan. RESULTS: Histologically, the lesions were characterized by a thin layer of proliferating, periosteally derived spindle cells overlying a thin, low-grade malignant cartilage cap that underwent calcification, neovascularization, and conversion into benign bone and marrow fat. These lesions were unique in that the malignant elements were only at their periphery. All six cases were initially misdiagnosed as benign lesions on pathologic evaluation. In each patient, imaging revealed a "pasted-on" ossified surface lesion with an intact underlying cortex and no medullary involvement. In three cases, recurrent tumors had histologic appearances consistent with conventional parosteal osteosarcoma. Dedifferentiation, metastases, and death occurred in one of these three cases. CONCLUSION: To our knowledge, this surface lesion of bone has not been specifically described. Whether this tumor constitutes a distinct entity or is a specialized variant of parosteal osteosarcoma is unclear. Precise radiologic-pathologic correlation is essential for appropriate diagnosis and management.

Miliary osteosarcomatosis with associated hypocalcemia.

We report the case of a patient with a rare miliary variant of osteosarcoma associated with symptomatic hypocalcemia and review the literature regarding the pathogenesis of multifocal osteosarcoma, treatment options, and the associated hypocalcemia.

Benign and malignant cartilage tumors of bone and joint: their anatomic and theoretical basis with an emphasis on radiology, pathology and clinical biology. I. The intramedullary cartilage tumors.

We reviewed 845 cases of benign and 356 cases of malignant cartilaginous tumors from a total of 3067 primary bone tumors in our database. Benign cartilaginous lesions are unique because the epiphyseal plate has been implicated in the etiology of osteochondroma, enchondroma (single or multiple), periosteal chondromas and chondroblastoma. In the first part of this paper, we will review important clinical, radiologic and histologic features of intramedullary cartilaginous lesions in an attempt to support theories related to anatomic considerations and pathogenesis.

Benign giant cell tumor of bone with osteosarcomatous transformation ("dedifferentiated" primary malignant GCT): report of two cases.

It is not uncommon for sarcomatous transformation of giant cell tumor (GCT) of bone to occur after radiation, but rarely does malignant transformation occur spontaneously, with less than 15 cases reported up to 1995. Only four of these cases have been documented in detail. We report two additional cases of GCT of bone spontaneously transforming or "dedifferentiating" into osteosarcoma without radiation therapy. The first case is absolutely unique and most interesting in that the dedifferentiation process occurred in one of multiple GCT lung metastases 6 years after successful eradication of a primary tibial tumor. The right lung was resected due to development of a large tumor, and at pathologic examination, demonstrated several small nodules of conventional GCT and a much larger, 14-cm mass composed of a mixture of GCT and high-grade osteosarcoma. The second case involved a physician, who had a large tumor in the sacrum with vague symptoms for 8 years. Open biopsy revealed conventional, benign GCT of bone with a secondary aneurysmal bone cyst. Complete curettage 2 weeks later revealed, in addition to areas of conventional, benign GCT a second component of very high grade osteosarcoma. Both patients died less than 1.5 years from diagnosis. This report of osteosarcomatous transformation of a conventional GCT of bone strengthens the theory that there is a mesenchymal cell line in GCT that may spontaneously transform to sarcoma.

Intraoperative pathologic consultation (IOC) for tumors of the bone.

When combining clinical examination, laboratory information and noninvasive imaging studies the differential diagnosis of bone lesions is narrowed. For those who are not experts in the field the major purpose of the IOC is to insure that adequate tissue has been obtained and to triage the tissue in the process preparing imprints, whenever possible; fixing some tissue for possible electron microscopic review; placing some tissue in B5 fixative for better cytologic detail; and to save some undecalcified tumor tissue in formalin in case immunostaining procedures are required. Most community pathologists should not be attempt to make an absolute diagnosis at the time of IOC, in many cases. The surgeon should always be warned that despite seeming benignancy 50% of primary bone tumors are malignant, that benign lesions can prove to be low grade sarcomas after full review, and vice versa that occasional cellular, "pleomorphic" lesions can be benign (aneurysmal bone cyst, early reparative and pseudosarcomatous lesions). Following review of the permanent sections, and other appropriate procedures an accurate diagnose is possible in the majority of cases. If the diagnosis is particularly difficult or questionable the above materials can be sent to a bone tumor specialist.

Fibrous cortical defect with bizarre nuclear features.

A femoral neck fibrous cortical defect with typical radiographic features had bizarre nuclear features on histological examination. Recognition of the benign radiographic appearance, similar bizarre features of accompanying macrophages, and paucity of mitoses led us to consider this a pseudoanaplastic ischemic or degenerative change in an old fibrous cortical defect. Because the biological behavior was not known with certainty, we closely followed this case. After 25 months, there has been no recurrence or regrowth. The close cooperation between the pathologist and other disciplines facilitates recognition of these pseudoanaplastic lesions and development of treatment strategies for lesions of unknown or uncertain biological behavior.

Clear-cell chondrosarcoma with elevated alkaline phosphatase, mistaken for osteosarcoma on biopsy.

This paper report a case of a pelvic clear-cell chondrosarcoma that was initially diagnosed as clear-cell osteosarcoma after needle biopsy. Preoperatively, laboratory studies revealed an elevated alkaline phosphatase and needle biopsy showed clear cells producing osteoid. Internal hemipelvectomy was performed and final pathology was most consistent with clear-cell chondrosarcoma, despite a negative S-100 immunohistochemical stain. Distinguishing between these two entities is clinically important because treatment differs. In this case, the patient did not receive pre-or postoperative chemotherapy and is disease free more than 2 years later.

Ribbing disease (multiple diaphyseal sclerosis): imaging and differential diagnosis.

OBJECTIVE: This study describes the clinical presentation and the course of Ribbing disease in six patients and illustrates imaging features on plain radiography, conventional and computed tomography, and 99mTc-methylene diphosphonate bone scans. MATERIALS AND METHODS: Between 1982 and 1990, six female patients presented with painful bony lesions that were believed to be Ribbing disease. Ten bones were affected: both tibiae in three patients, a unilateral tibia in one, both femora in one, and a unilateral femur in one. Plain radiographs and either conventional or computed tomography were available for all patients and 99mTc-methylene diphosphonate bone scans, for five patients. All patients underwent open biopsy and/or surgical decompression. RESULTS: The diagnosis was reached in all patients through a combination of clinical findings (lack of systemic signs of infection or laboratory values suggesting metabolic bone disease), imaging, histologic evaluation, and specimen cultures. Radiographs and tomographic studies showed benign-appearing endosteal and periosteal cortical thickening. Intense uptake of radionuclide tracer was confined to the shaft of all involved bones. All pathologic specimens revealed nonspecific changes that included a slow increase in the mass of cortical and endosteal bone. These specimens also assisted in excluding neoplastic or infectious causes for the new bone formation. CONCLUSION: Ribbing disease is a rare disorder that, on imaging studies, may simulate stress fracture, chronic infection, bone-forming neoplasia, or a systemic metabolic or endocrine disorder. Clinical and imaging features may suggest the correct diagnosis.