Deborah M. Forrester

Giant Cell Tumor of Bone: Review, Mimics, and New Developments in Treatment

Giant cell tumor (GCT) of bone is generally a benign tumor composed of mononuclear stromal cells and characteristic multinucleated giant cells that exhibit osteoclastic activity. It usually develops in long bones but can occur in unusual locations. The typical appearance is a lytic lesion with a well-defined but nonsclerotic margin that is eccentric in location, extends near the articular surface, and occurs in patients with closed physes. However, GCT may have aggressive features, including cortical expansion or destruction with a soft-tissue component. Fluid-fluid levels, consistent with secondary formation of aneurysmal bone cysts, are seen in 14% of cases. GCT can mimic or be mimicked by other benign or malignant lesions at both radiologic evaluation and histologic analysis. Rarely, GCT is associated with histologically benign lung metastases or undergoes malignant degeneration. In the past, the mainstay of treatment was surgical, primarily consisting of curettage with cement placement, with recurrence rates of 15%-25%. Recurrence is suggested by development of progressive lucency at the cement-bone interface. Other complications include pathologic fracture and postoperative infection. Denosumab, a monoclonal antibody that targets the osteoclastic activity of GCT, has produced 90% tumor necrosis in early studies, results indicative of promise as a potential adjuvant therapy.

Avulsion Fractures of the Knee: Imaging Findings and Clinical Significance

The knee is an intricate joint with numerous tendinous, ligamentous, and meniscal attachments, which make it particularly vulnerable to complex injuries after trauma. A variety of avulsion fractures of the knee can occur, including Segond and reverse Segond fractures; avulsions of the anterior and posterior cruciate ligaments; arcuate complex avulsion; iliotibial band avulsion; avulsions of the biceps femoris, semimembranosus, and quadriceps tendons; Sinding-Larsen-Johansson syndrome; and Osgood-Schlatter disease. These fractures often have a subtle appearance at conventional radiography, which is typically the first imaging modality performed in these cases. Advanced imaging modalities, particularly magnetic resonance imaging, are helpful and can provide valuable additional information for adequately defining the extent of damage. The onus is on the radiologist to identify the pattern of injury and to understand the substantial underlying damage that it frequently represents. Conveying this information to the referring clinician is crucial and represents the first step toward additional evaluation and probable orthopedic referral. By recognizing the significance of these injuries at initial presentation, radiologists can facilitate appropriate patient work-up and prevent the chronic morbidity associated with delayed treatment.

Sclerosing Bone Dysplasias: Review and Differentiation from Other Causes of Osteosclerosis

Sclerosing bone dysplasias are skeletal abnormalities of varying severity with a wide range of radiologic, clinical, and genetic features. Hereditary sclerosing bone dysplasias result from some disturbance in the pathways involved in osteoblast or osteoclast regulation, leading to abnormal accumulation of bone. Several genes have been discovered that, when disrupted, result in specific types of hereditary sclerosing bone dysplasia (osteopetrosis, pyknodysostosis, osteopoikilosis, osteopathia striata, progressive diaphyseal dysplasia, hereditary multiple diaphyseal sclerosis, hyperostosis corticalis generalisata), many of which exhibit similar pathologic mechanisms involving endochondral or intramembranous ossification and some of which share similar underlying genetic defects. Nonhereditary dysplasias include intramedullary osteosclerosis, melorheostosis, and overlap syndromes, whereas acquired syndromes with increased bone density, which may simulate sclerosing bone dysplasias, include osteoblastic metastases, Paget disease of bone, Erdheim-Chester disease, myelofibrosis, and sickle cell disease. Knowledge of the radiologic appearances, distribution, and associated clinical findings of hereditary and nonhereditary sclerosing bone dysplasias and acquired syndromes with increased bone density is crucial for accurate diagnosis.

Gorham’s disease of the radius: radiographic, scintigraphic, and MRI findings with pathologic correlation

Abstract A rare case of Gorham’s disease affecting the radius in a 46-year-old woman is presented. It was studied by plain radiography, MRI, and scintigraphy, including three-phase radionuclide bone scan and thallium scan. Three-phase bone scan demonstrated slightly decreased activity in the affected portion of the forearm in the early phase, but showed increased activity on the blood pool and delayed imaging. A thallium scan revealed no abnormalities. Histopathologic examination revealed osteoclastic activity and scar tissue with minimal remaining vasculature.

Multicentric giant cell tumor: report of five new cases

The typical giant cell tumor (GCT) is a solitary neoplasm that occurs in the epiphysis or epimetaphysis of long bones. GCT is seen with a slightly increased frequency in females, and 70% of patients are between 20 and 40 years of age at the time of presentation. Multicentric giant cell tumor (MGCT; two or more centers) is an unusual variant of GCT. Patients with MGCT are likely to be younger than those with a solitary lesion. The multicentric variety is often of a higher stage at diagnosis and is more often associated with a pathological fracture than the unifocal tumor. We are reporting five new cases of MGCT, with a total of 21 tumors seen over a period of 25 years from 1967 to 1992.

Cruciate ligament avulsion fractures: Anatomy, biomechanics, injury patterns, and approach to management

Injury to the ACL or PCL of the knee most commonly involves a tear of the collagenous fibers of the ligament. Less frequently, a cruciate ligament injury involves an avulsion fracture at the origin or insertion of the ligament, usually from the insertion site on the tibial surface. Avulsion fractures of the cruciate ligaments are important, as they can be identified on radiographs, allowing a specific diagnosis. Although more common in children, when they occur in adults, they are more commonly associated with other injuries. The treatment of cruciate ligament avulsion fractures is different than the treatment of intrasubstance tears of the cruciate ligaments. These injuries can be treated conservatively or surgically with good outcomes. Recently arthroscopic fixation of these injuries with various fixation devices has become more frequent. Treatment largely depends on the type of fracture, particularly, the size, displacement, comminution, and orientation of the avulsed fracture fragment, in addition to the integrity of the attached cruciate ligament. This review article covers the anatomy and biomechanics of the cruciate ligaments, their injury patterns, and approach to management.

Transient lateral patellar dislocation: review of imaging findings, patellofemoral anatomy, and treatment options

Transient patellar dislocation is a common sports-related injury in young adults. Although patients often present to the emergency department with acute knee pain and hemarthrosis, spontaneous reduction frequently occurs, and half of cases are unsuspected clinically. Characteristic magnetic resonance imaging (MRI) findings often lead to the diagnosis. The purpose of this review is to illustrate the MRI findings of lateral patellar dislocation and concomitant injuries, such as kissing contusions of the medial patella and lateral femoral condyle; osteochondral and avulsion fractures; and injuries of the medial patellofemoral ligament/retinacular complex. This article will also briefly review patellofemoral anatomy and passive, active, and static stabilizers. Predisposing factors for patellar instability, including trochlear dysplasia, patella alta, and lateralization of the patella or tibial tuberosity and their relevant measurements will also be highlighted. Treatment options, including surgery, such as medial patellofemoral ligament reconstruction, tibial tuberosity transfer, and trochleoplasty, and their postoperative imaging appearances will also be discussed.

Structure and function, injury, pathology, and treatment of the medial collateral ligament of the knee.

The medial collateral ligament (MCL) is the most commonly injured ligament of the knee. There is a spectrum of injury severity, and injuries may be acute or chronic. The MCL is also frequently injured in conjunction with other knee structures. Clinical evaluation of the knee is important to assess the degree of surgical acuity, but magnetic resonance imaging can provide details about the injury that may not be obvious clinically. In addition to injury, MCL bursitis can occur and may be treated with needle aspiration and corticosteroid injection. This review article covers the anatomy and biomechanics of the MCL, its injury patterns and approach to management, and MCL bursitis.

Case report 749

We report a case of primary intraosseous glomus tumor in a 30-year-old man who was found to have an expanding, lytic lesion in the distal phalanx of his left thumb. The histological appearance was atypical in that areas of myxoid stroma resembled chondroid material. The unusual location and microscopic appearance caused diagnostic problems. Immunohistochemical studies, including strong positive staining for MSA and negative staining for keratin and S-100 protein, were helpful in establishing the correct diagnosis.

Radionuclide imaging in forme fruste of melorheostosis.

Scintigraphy was instrumental in two histologically proven cases of forme fruste melorheostosis. Radionuclide bone scans demonstrated a moderately increased uptake of radiopharmaceutical localized to the “flowing” cortical hyperostosis of melorheostosis observed radiographically. The medullary portion of the affected bones showed no increase in tracer activity. In one case, imaging with TI-201 chloride demonstrated increased focal activity of the lesion. These scintigraphic findings can help distinguish the mildest manifestation (forme fruste) of melorheostosis from the well-ossified lesions of myositis ossificans and parosteal or periosteal osteosarcoma. The findings of MRI are also described in one patient.