Chondroblastoma: classic and confusing appearance at MR imaging

Periosteal chondroblastoma of the femoral neck: two cases and a review of the literature

Chondroblastoma is a rare benign cartilaginous tumor mostly confined to the epiphyses and apophyses. Cases outside the epiphyseal region are exceedingly rare. Extramedullary chondroblastomas are exceptional; to our knowledge, only two cases qualified as "periosteal chondroblastoma" have been described in the literature. We report two cases of metaphyseal periosteal chondroblastoma both located on the inferior surface of the femoral neck. Both cases were paucicellular with an unusual dense sclerotic reaction. The diagnosis of chondroblastoma was supported by the expression of histone 3.3, K36M mutant in tumor cells.

Osteoid osteoma appearing after bony fracture in a girl with osteogenesis imperfecta

Osteoid osteoma (OO) is a common, benign bone tumor. However, there are no case reports of OO associated with osteogenesis imperfecta (OI), or pathological fractures in OO. A 3-year-old girl with OI sustained a complete right tibial diaphyseal fracture. Bony fusion was completed after 4 months of conservative therapy; nevertheless, 18 months later spontaneous pain appeared at the fracture site, without any cause. Plain radiographs showed a newly apparent, rounded area of translucency 1 cm in diameter, just overlapping the previous fracture. Images obtained using three-dimensional time-resolved contrast-enhanced magnetic resonance angiography showed strong central enhancement in the early phase, with an apparent nidus, suggesting the diagnosis of OO. Nineteen months after the first fracture, while skipping, the patient refractured her tibial diaphysis at the site of the previous fracture. This is a very rare case of OO, apparently co-existing with OI and leading to a bony fracture. In our case, the combination of bone fragility in OI and a recent fracture at the site of the OO may have caused the re-fracture.

A rare case of chondroblastoma involving the distal phalanx of the ring finger

Chondroblastoma, a rare benign bone tumor, is typically found in the epiphysis of long bones, with hand involvement being particularly uncommon. We present a case of an 11-year-old female with chondroblastoma involving the fourth distal phalanx of the hand. Imaging revealed a lytic, expansile lesion with sclerotic margins and no soft tissue component. A preoperative differential diagnosis included intraosseous glomus tumor, epidermal inclusion cyst, enchondroma, and chronic infection. The patient underwent open surgical biopsy and curettage for both diagnostic and treatment purpose. The final histopathologic diagnosis was chondroblastoma.

Chondroblastoma of foot bones; a clinicopathological study of 29 cases confirming the diagnostic utility of H3K36M and H3G34W antibodies at an uncommon site

OBJECTIVE

Chondroblastoma (CB) is a benign cartilaginous bone neoplasm which commonly occurs in long bones of adolescents. CB can uncommonly involve foot. Its mimics include both benign and malignant lesions. H3K36M immunohistochemical (IHC) stain is a helpful tool for establishing the diagnosis of CB in such challenging situations. In addition, H3G34W IHC stain helps to rule out giant cell tumor which is the closest differential of CB. Our objective was to describe the clinicopathological features and frequencies of H3K36M, H3G34W and SATB2 IHC stains in CB of foot.

MATERIALS AND METHODS

We reviewed H&E slides and blocks of 29 cases diagnosed as "chondroblastoma" of foot at our institutions.

RESULTS

Patient's age ranged from 6 to 69 (mean: 23.3 and median: 23) years. Males were almost 5 times more commonly affected than females. Talus and calcaneum were involved in 13 (44.8 %) cases each. Microscopically, tumors were composed of polygonal mononuclear cells and multinucleated giant cells and chondroid matrix. Other histological features included aneurysmal bone cyst-like (ABC-like) change (44.8 %), osteoid matrix (31 %), chicken-wire calcification (20.7 %), and necrosis (10.3 %). H3K36M was expressed in 100 % and SATB2 in 91.7 % cases. H3G34W was negative in all cases, where performed. One out of 11 patients with follow up information developed local recurrence after 48 months.

CONCLUSION

CB in foot occur at an elder age and show more frequent ABC-like changes as compared to long bones. Males are affected ~5:1 as compared to 2:1 in long bones. H3K36M are H3G34W are extremely useful diagnostic markers for CB, especially elderly (aged or higher) patients and we report the largest series of foot CB cases confirmed by immunohistochemistry.

Benign Bone Lesions Found in Childhood

Benign bone tumors are a wide variety of usually asymptomatic neoplasms, which in most cases are diagnosed due to secondary causes. As such, their real incidence is unknown. In the majority of cases, plain radiographs are enough for diagnosis; more advanced imaging, such as CT scan or MRI is sometimes performed for equivocal lesions. Treatment approach depends on whether the lesion is symptomatic and the risk of further progression, or development of secondary malignancies. When non expectant management is decided, treatment options include minimally invasive methods and surgery.

Imaging Review of Normal and Abnormal Skeletal Maturation

The growing skeleton undergoes well-described and predictable normal developmental changes, which may be misinterpreted a as pathologic condition at imaging. Primary and secondary ossification centers (SOCs), which form the diaphysis and the epiphysis of long bones, respectively, are formed by endochondral and intramembranous ossification processes. During skeletal maturation, the SOCs may appear irregular and fragmented, which should not be confused with fractures, osteochondritis dissecans, and osteochondrosis. These normal irregularities are generally symmetric with a smooth, round, and sclerotic appearance, which are aspects that help in the differentiation. The metaphysis, epiphysis, and growth plates or physes are common sites of injuries and normal variants in the pediatric skeleton. The metaphysis contains the newly formed bone from endochondral ossification and is highly vascularized. It is predisposed to easy spread of infections and bone tumors. The physis is the weakest structure of the immature skeleton. Injuries to this location may disrupt endochondral ossification and lead to growth disturbances. Pathologic conditions of the epiphyses may extend into the articular surface and lead to articular damage. At MRI, small and localized foci of bone marrow changes within the epiphysis and metaphysis are also a common finding. These can be related to residual red marrow (especially in the metaphysis of long bones and hindfoot), focal periphyseal edema (associated with the process of physeal closure), and ultimately to a normal ossification process. The authors review the imaging appearance of normal skeletal maturation and discuss common maturation disorders on the basis of developmental stage and location. ^©RSNA, 2022.

Sacral chondroblastoma — a rare location, a rare pathology: A case report and review of literature

BACKGROUND

Chondroblastoma (CB) is an intermediate tumor of cartilage origin. CB involving the sacrum is a very rare pathology.

CASE SUMMARY

A 17-year-old male with sacral CB was diagnosed as CB during the first surgery, and 18 mo later, the tumor recurred and a second surgery was performed with the same pathology result of CB.

CONCLUSION

We recommend complete removal of the tumor in a timely manner, provided that surgical conditions are met. At the same time, other diseases should be carefully differentiated in terms of imaging or pathological features so as to avoid erroneous diagnostic conclusions.

Bilateral osteochondral defects of the patellae in an 11-year-old girl

Osteochondral defect or osteochondritis dissecans (OCD) of the knee usually affects young, active populations. It is a challenging diagnosis as patients typically present with poorly localised activity-related pain, which is non-specific and covers many differentials. We present an active 11-year-old girl with bilateral osteochondral defects of the patellae: a rare clinical disorder which was affecting her sporting activities. She had a 12-month history of bilateral anterior knee pain before the diagnosis was achieved with appropriate imaging. Her pain significantly improved with activity modification and physiotherapy. Follow-up will require outpatient clinic assessment and imaging to determine if non-operative management continues to be successful or surgery may be required. This case report emphasises the importance of appropriate high index of suspicion when managing patients with non-specific knee pain. It also demonstrates the importance of judicious use of imaging to avoid a missed or delayed diagnosis.

Secondary aneurysmal bone cysts and associated primary lesions: imaging features of 49 cases

PURPOSE

To describe the imaging, anatomic, and clinical features of a series of secondary aneurysmal bone cysts (ABC) and to ascertain their most commonly associated primary bone lesions.

METHODS

Forty-nine cases of histopathologically proven secondary ABCs were retrospectively reviewed. Demographic data and clinical history were obtained. Radiographic, computed tomographic, magnetic resonance, and nuclear medicine imaging were analyzed. Lesion location, imaging characteristics, and associated primary lesions were documented. Linear regression analysis and Chi-squared testing was performed for statistical analysis.

RESULTS

Twenty-four males and 25 females were included, with an age range of 8-79 years (mean 29.7 + - 4.5 years). Eleven types of primary bone lesion were identified, with giant-cell tumor (n = 17, 35%), chondroblastoma (n = 11, 22%), fibrous dysplasia (n = 6, 12%), osteoblastoma (n = 4, 8%) and osteosarcoma (n = 4, 8%) being the most frequent. The lesions involved chiefly the long bone epiphyses (n = 25, 51%). Secondary ABC imaging findings and locations most closely approximated those of their primary counterparts, although fluid-fluid levels were seen at a higher frequency than previously reported in primary chondroblastoma (9/11, 82%), fibrous dysplasia (2/6, 33%), osteoblastoma (4/4, 100%), osteosarcoma (3/4, 75%), and chondromyxoid fibroma (1/2, 50%).

CONCLUSION

The most common primary lesions associated with secondary ABC were giant cell tumor and chondroblastoma, located in the long bone epiphyses. The majority of the secondary ABCs demonstrate predominant imaging characteristics typical of the primary bone lesions, but with a higher presence of fluid-fluid levels.

Tumours of the talus - A pictorial review

BACKGROUND

Primary bone tumours of the talus are a rare entity and seldom described in the literature. Due to this, often the diagnosis and management of such cases are delayed. This study aims to describe a spectrum of lesions identified within our department and provide a pictorial review with the goal to aid radiologists in the evaluation and diagnosis of such lesions.

MATERIALS & METHODS

A retrospective study was conducted within our department, identifying all talar lesions, confirmed on histopathological and radiological diagnosis.

RESULTS

Results revealed 75 cases of talar lesions. Benign tumours formed the bulk of the lesions identified accounting for 85% of all cases. The most common benign tumour was chondroblastoma (n = 23). Malignant tumours were detected in 6 cases. Other lesions included osteomyelitis and avascular necrosis.

CONCLUSION

We present a variety of tumours and tumour-like conditions of the talus. Radiologists as well as orthopaedic surgeons need to be aware of such lesions, to prompt early diagnosis and initiate management in timely fashion.

Edema Surrounding Benign Tumors and Tumor-Like Lesions

Objective

To explore the incidence and significance of intra- and extra-osseous edema associated with benign tumors and tumor-like diseases.

Methods

Magnetic resonance imaging (MRI) data from 300 benign osseous tumors and tumor-like diseases diagnosed by pathology were retrospectively reviewed. Borderline tumors, cases associated with pathological fractures, and skull lesions were excluded from the study. Bone marrow and soft tissue edema were defined on T2WI with fat suppression on MRI in all cases. The incidence rate of edema in benign tumors and tumor-like diseases was determined using the χ ² test. The preoperative diagnoses were reviewed, and the effect of edema on the differential diagnosis of benign and malignant tumors was analyzed.

Results

The incidence rate of bone marrow and soft tissue edema associated with benign tumors and tumor-like diseases was 35.7% (107/300), including 84.4% (27/32) Langerhans cell histiocytosis, 86.4% (19/22) osteoblastoma, 93.9% (31/33) osteoid osteoma, and 85.2% (23/27) chondroblastoma cases. There was no statistically significant difference in the incidence of edema among the four diseases (χ ² = 1.7, P > 0.05). Of 107 cases associated with edema, 49 (45.8%) were misdiagnosed as malignant tumors by MRI preoperatively.

Conclusion

Bone marrow and soft tissue edema are a common finding associated with benign bone tumors and tumor-like diseases, and they are frequently detected in Langerhans cell histiocytosis, osteoblastoma, osteoid osteoma, and chondroblastoma.

Chondroblastoma of the Foot: 40 Cases From a Single Institution

Chondroblastoma (CB) of the foot is a rare lesion. The purpose of this report was to report a large series from a single institution to analyze clinical, radiographic, and histologic characteristics; treatment; and local recurrence. We present 40 patients (30 males, 10 females; mean age 25 years) diagnosed and treated for CB of the foot from 1975 to 2012. The mean follow-up visit was 55 months (range 7 months to 11 years). Clinical presentation, histology, imaging, surgical treatment, and local recurrence were evaluated. Males were more affected than females. The main symptom was pain (100%) accompanied by swelling (35%), with median duration of 12 months. The talus (50%) and calcaneus (37.5%) were the most affected bones. All patients underwent surgery: curettage (10 cases), curettage and bone graft (15 cases), curettage and cement (13 cases), wide resection (1 case), and Chopart amputation (1 case). Ten patients (25%) had secondary aneurysmal bone cyst. One patient had local recurrence after surgery. In conclusion, patients with CB of the foot are usually older than 20 years, and males are most affected. The hindfoot is the most affected area. Surgical treatment is required, and intralesional curettage and packing with cement or graft is curative in most cases. Local recurrence in foot is lower than in other locations.

Bone and Soft Tissue Tumors About the Foot and Ankle

The foot and ankle delicately balance the need for support of the weight of the human body, with the need for flexibility. Palpable masses about the foot and ankle, therefore, are most commonly related to trauma or mechanical instability. Non-neoplastic causes, such as ganglion cysts and callus, therefore, predominate. However, the radiologist must be aware of the imaging appearance of less common benign and malignant neoplasms that can involve the foot and ankle.

Isolated delayed metastasis to the talus from Ewing's sarcoma

Bone metastasis to the hands and feet, known as acrometastasis, is a very rare finding and tends to be associated with extensive metastasis. We herein report the case of a 14-year-old girl known to have a history of successfully treated Ewing's sarcoma arising from the ribs, who presented with a pathologically proven isolated metastatic lesion to the talus 7 years after achieving clinical and radiologic remission. We describe the imaging findings on MRI, CT scan and PET-CT. To our knowledge, talar metastasis from Ewing's sarcoma has been previously reported only twice in the English literature. Noteworthy is the fact that one of the previously reported lesions was considered a skip metastasis, and the other was under-described in terms of primary and secondary tumor location and time to metastasis. In addition, the overall imaging findings were rather suggestive of a benign lesion, particularly on CT scan.

Epithelioid hemangioma of bone: radiologic and magnetic resonance imaging characteristics with histopathological correlation

BACKGROUND

Epithelioid hemangioma is a rare vascular tumor that can occur in soft tissues or bone. The tumor is part of a spectrum of vascular tumors that also includes epithelioid hemangioendothelioma and angiosarcoma. When involving the bone, the tumor usually involves the metaphysis or diaphysis of the long tubular bones and most commonly occurs in adults. It has been rarely reported in pediatric patients, and in these reported patients, the tumor primarily involves the epiphysis.

OBJECTIVE

To review three cases of epithelioid hemangioma of bone occurring in pediatric patients involving the epiphysis and to explore the imaging features of this tumor.

MATERIALS AND METHODS

Retrospectively review three cases of epithelioid hemangioma occurring in skeletally immature patients.

RESULTS

These tumors primarily involved the epiphyses or epiphyseal equivalent bones. One lesion was centered in the metaphysis but extended to the epiphysis. These are three cases presenting in an unusual location and at an unusual age.

CONCLUSION

Epithelioid hemangioma, though rare, can occur in pediatric patients and appears to involve the epiphyses in these patients. This is in contrast to the usual age and location reported. Epithelioid hemangioma may be considered for an epiphyseal lesion in a skeletally immature patient.

Chondroblastoma of the thoracic spine: a rare location. Case report with radiologic-pathologic correlation

Chondroblastoma is a rare benign cartilage neoplasm that arises from the appendicular skeleton in the vast majority of the cases (80%). Chondroblastoma of the spine is an even more rare condition (30 cases reported), and vertebral chondroblastomas, unlike chondroblastomas of the extremities, present with the appearance of an aggressive tumor on CT and MR imaging and occur at least a decade later. Even though vertebral chondroblastomas are very uncommon tumors, they should nonetheless be included in the differential diagnosis when encountered with an aggressive vertebral mass, and a histological confirmation should be performed. We present a case of chondroblastoma of the thoracic spine of a 27-year-old female for which detailed radiologic-pathologic correlation was obtained.

Advanced Imaging of the Scapula: What Every Radiologist Needs to Know

The scapula plays a central role in shoulder motion and stability. A wide variety of anatomic variants as well as traumatic, neoplastic, and infectious pathologies can involve the scapula. Detection of scapular lesions using radiography can be challenging because of the obscuration by the overlying structures or incomplete imaging during shoulder magnetic resonance imaging or computed tomography examinations. Familiarity with imaging characteristics of these abnormalities will allow radiologists to better diagnose and characterize scapular disorders.

Surface-based chondroblastoma of the tibia: a unique presentation

BACKGROUND

Chondroblastoma is a benign tumor classically located within the epiphysis of the long bones. The tumor is believed to arise from immature cells of the epiphyseal plate. Purely metaphyseal or diaphyseal chondroblastoma is exceedingly uncommon, occurring in approximately 2% of chondroblastoma cases. In all of these non-epiphyseal-based cases, the tumor has been intramedullary.

METHODS

We describe the histologic and imaging features of the first detailed description of a surface-based chondroblastoma.

RESULTS

The tumor was located in the anteromedial midshaft of the tibia in a 47-year-old male.

CONCLUSION

We discuss the diagnostic considerations and possible etiology of chondroblastoma given this unusual location.

Calcaneal chondroblastoma with pathologic fracture and recurrence

Chondroblastomas account for <2% of all bone tumors. The calcaneus is the fifth most common location of occurrence. Males in their second decade of life are most often affected, presenting with an insidious onset of localized pain, swelling, and tenderness. The finding of associated pathologic fracture has been rare. Imaging studies can aid in the formulation of the differential diagnosis and surgical plan. The definitive diagnosis requires histologic examination. Curettage and bone grafting is curative in >80% of cases. Local recurrence rates of ≤38% have been reported, most often because of inadequate resection, and have been associated with malignant conversion and metastasis. Adjuvant therapies can help minimize the incidence of local recurrence. Long-term follow-up examinations are recommended, given the protracted interval that can exist between recurrence and the potential for malignant conversion and metastasis. We present the case of a young, healthy, active male with a calcaneal chondroblastoma and associated pathologic fracture whose initial treatment consisted of curettage, hydrogen peroxide lavage, and allogeneic bone grafting. Recurrence developed at 15 months postoperatively and was treated with repeat curettage, high-speed burring, and reconstruction with steel Steinman pins and polymethylmethacrylate, resulting in no pain or recurrence at the 5-month follow-up point.

Chondroblastoma of the triquetrum

Chondroblastoma is a relatively uncommon but benign bone tumor that is typically found in a long-bone epiphysis. Reports of this type of tumor in the carpals have been rare, and even fewer cases of such tumors in the triquetrum have been reported. Here, we present classical findings of a chondroblastoma at an unusual location, the triquetrum, in an adolescent. Fat-suppressed T2*-weighted imaging revealed a hyperintense tumor matrix replacing the bony trabecula of the triquetrum, which had not been addressed in previous literature. Radiography-based differential diagnosis of a bubbly lesion in the hand of an adolescent, even in the small carpal bones, should include chondroblastoma.

Chondroblastoma and chondromyxoid fibroma

Chondroblastoma and chondromyxoid fibroma are benign but locally aggressive bone tumors. Chondroblastoma, a destructive lesion with a thin radiodense border, is usually seen in the epiphysis of long bones. Chondromyxoid fibroma presents as a bigger, lucent, loculated lesion with a sharp sclerotic margin in the metaphysis of long bones. Although uncommon, these tumors can be challenging to manage. They share similarities in pathology that could be related to their histogenic similarity. Very rarely, chondroblastoma may lead to lung metastases; however, the mechanism is not well understood.

The imaging of cartilaginous bone tumours. I. Benign lesions

Benign cartilage tumours of bone are the most common benign primary bone tumours and include osteochondroma, (en)chondroma, periosteal chondroma, chondroblastoma and chondromyxoid fibroma. These neoplasms often demonstrate typical imaging features, which in conjunction with lesion location and clinical history, often allow an accurate diagnosis. The aim of this article is to review the clinical and imaging features of benign cartilage neoplasms of bone, as well as the complications of these lesions.

Bony sequestrum: a radiologic review

According to a pathological definition, a bony sequestrum is defined as a piece of devitalized bone that has been separated from the surrounding bone during the process of necrosis. However, the radiological definition of a sequestrum is different and refers to an image of calcification visible within a lucent lesion, completely separated from the surrounding bone, without referring to the vascular status and histological nature of the calcified tissue. The term "button sequestrum" has been used in calvarial lesions. The prototype conditions that may present with a bony sequestrum are osteomyelitis and skeletal tuberculosis. Other conditions such as radiation necrosis, eosinophilic granuloma, metastatic carcinoma, primary lymphoma of bone, aggressive fibrous tumors may also manifest as osteolytic lesions containing a sequestrum. In addition, some primary bone tumors produce a matrix that may mineralize and sometimes simulate a bone sequestrum. These include osteoid tumors (osteoid osteoma, osteoblastoma), cartilaginous tumors (chondroma and chondroblastoma), lipomatous tumors (lipoma), and benign fibrous tumors (fibromyxoma, myxoma, and desmoplastic fibroma). Therefore, various conditions may present at imaging as a small area of osteolysis containing central calcifications. However, a careful analysis of the sequestrum as well as the associated clinical and radiological findings often enables to point toward a limited number of conditions.

Radiologic diagnosis of osteoid osteoma: from simple to challenging findings

Osteoid osteoma is characterized by an intracortical nidus with a variable amount of calcification, as well as cortical thickening, sclerosis, and bone marrow edema. When these findings are present, a diagnosis of osteoid osteoma is easily made. However, osteoid osteoma may display imaging findings that can be misleading, and it can be difficult to differentiate osteoid osteoma from other conditions such as infection, inflammatory and noninflammatory arthritis, and other tumors. In addition, stress fracture, intracortical abscess, intracortical hemangioma, chondroblastoma, osteoblastoma, and compensatory hypertrophy of the pedicle may mimic osteoid osteoma. To make the correct diagnosis, it is necessary to identify the nidus, and it is important to be familiar with the radiologic findings of osteoid osteoma and its mimics.

Bone marrow oedema of the knee

Magnetic resonance (MR) imaging is a frequently performed investigation for disease of the knee. Bone marrow oedema (BME) is a common MR finding with a number of causes including trauma, tumour, infection, inflammatory arthropathies and BME syndromes. This article illustrates the range of MR appearances of BME around the knee and describes secondary signs that allow the reader to determine the cause of disease and to distinguish BME from normal marrow signal changes.

[Imaging findings in chondroblastoma]

OBJECTIVE

To describe the imaging findings, with special emphasis on the magnetic resonance (MRI) findings and the clinical and radiological presentation of chondroblastoma.

MATERIAL AND METHODS

This is a retrospective study of 18 patients (12 men and 6 women; mean age, 19 years) diagnosed with chondroblastoma. All patients underwent plain-film radiography, 16 underwent MRI, and 12 underwent CT. We evaluated the location, size, pattern of bone destruction, calcification of the tumor matrix, periosteal reaction, signal intensity on T1- and T2-weighted sequences, and the presence of bone or soft-tissue edema.

RESULTS

The lesions were located in the distal femur (n = 6), proximal humerus (n = 5), ilium (n = 3), proximal femur, proximal tibia, patella, and scapula. Mean lesion diameter was 3.5 cm (range: 1 to 10 cm). A calcified tumor matrix was observed in 50% of the cases and a periosteal reaction was seen in 44%. MRI showed a homogeneous intramedullary lesion that was isointense to muscle on T1-weighted sequences. On T2-weighted sequences, the signal intensity was more variable and was always heterogeneous. Perilesional edema affecting the bone and/or soft tissues was demonstrated in 94% of the cases and is a distinctive finding for this tumor.

CONCLUSIONS

Chondroblastoma should be suspected in a young patient with an osteolytic epiphyseal lesion. It is usually a localized lesion that often shows calcification of the tumor matrix and periosteal reaction. CT and especially MRI are useful in the study of the extension of the lesion and in the characterization of this tumor. Chondroblastoma typically shows bone edema, periosteal reaction, and soft-tissue edema.

Subperiostial recurrence of chondroblastoma

We present a case of subperiosteal recurrence of chondroblastoma adjacent to the greater trochanter that was initially thought to represent septic arthritis of the hip in a 10-year-old girl. Soft-tissue recurrence of chondroblastoma is very rare, with fewer than ten cases reported in the literature. We demonstrate the recurrence on both CT and MRI. The MRI clearly demonstrates the soft-tissue recurrence and the associated inflammatory changes, with signal characteristics not unlike the primary tumor.

Proximal tibial epiphyseal intraosseous schwannoma: a rare entity

Schwannoma is a benign nerve sheath tumor most commonly located in the soft tissue. Occasionally, schwannomas involve osseous structures. The rarity of osseous involvement leads to omission of schwannoma from the initial differential diagnosis in the majority of cases. Intraosseous schwannomas arising in children have not been reported. We present the case of a schwannoma affecting the proximal tibial epiphysis in a growing child. Intraosseous schwannomas should be included in the differential diagnosis of lytic epiphyseal benign-appearing bone lesions in children. Its radiographic characteristics mimic those of benign chondroblastoma.

Role of MRI in paediatric musculoskeletal conditions

The aim of this review is to discuss the indications and use of MR imaging (MRI) in the paediatric musculoskeletal system. After briefly reviewing basic technical considerations the MRI appearance of the most relevant congenital, inflammatory, infectious, ischemic, and posttraumatic skeletal conditions, as well as benign and malignant bone and soft tissue tumours that are typical for the paediatric age group will be presented.

Bone marrow oedema associated with benign and malignant bone tumours

Bone marrow oedema is associated with a wide variety of pathological processes including both benign and malignant bone tumours. This imaging finding in relation to intraosseous tumours can aid in providing a more focused differential diagnosis. In this review, we will discuss the MR imaging of bone marrow oedema surrounding intraosseous neoplasms. The different pulse sequences used in differentiating underlying tumour from surrounding oedema are discussed along with the role of dynamic contrast enhanced MRI. Benign lesions commonly associated with bone marrow oedema include osteoid osteoma, osteoblastoma, chondroblastoma and Langerhan's cell histiocytosis. Metastases and malignant primary bone tumours such as osteosarcoma, Ewing's sarcoma and chondrosarcoma may also be surrounded by bone marrow oedema. The imaging findings of these conditions are reviewed and illustrated. Finally, the importance of bone marrow oedema in assessment of post chemotherapeutic response is addressed.

Radiofrequency ablation of two femoral head chondroblastomas

Chondroblastoma is a rare benign cartilaginous bone tumor. Surgical resection is the treatment of choice for pain relief and prevention of further growth. Open surgical techniques are associated with complications, particularly when the tumors are located in deep anatomical sites. The authors performed RF ablation in two cases of subarticular femoral head chondroblastomas and emphasize its positive impact. The clinical course, the radiological findings and the post treatment results are discussed.

MRI of bone marrow oedema associated with focal bone lesions

AIM

To quantify the volume of bone marrow oedema surrounding focal bone lesions and to identify its relevance relative to diagnosis.

METHODS

Three hundred and eighty-eight of 1456 patients included in the orthopaedic oncology database who underwent magnetic resonance imaging (MRI) demonstrated bone marrow oedema and were included in the study. There were 225 males and 163 females, age range 1-87 years (mean 29 years). MRI images were retrospectively reviewed and assessed for the extent of bone marrow oedema. The amount of oedema was graded: grade 1: oedema present but smaller than the lesion size; grade 2: oedema equivalent to the lesion size; grade 3: oedema greater than the lesion size.

RESULTS

There were 190 grade 1 lesions: 56% malignant, 33% benign, 11% non-neoplastic; 74 grade 2 lesions: 19% malignant, 50% benign, 31% non-neoplastic; and 124 grade 3 lesions: 10% malignant, 46% benign, 44% non-neoplastic. There was a significant relationship between oedema grade (i.e., volume of oedema) and final diagnosis (p<0.0005).

CONCLUSION

Bone marrow oedema may be associated with a wide range of focal bony lesions, including malignant, benign and non-neoplastic causes. As the volume of bone marrow oedema increases relative to the size of the underlying lesion, the probability that the underlying lesion is benign is increased.

False positive 18F-FDG PET in an ischial chondroblastoma; an analysis of glucose transporter 1 and hexokinase II expression

We report a rare case of chondroblastoma arising from the ischium which showed an increased (18)F-FDG uptake. Chondroblastoma is an uncommon lesion and usually involves the epiphysis of long bones. However, in this case, the tumor appeared as a well-defined osteolytic lesion in the ischium on radiographs. MR imaging demonstrated two components in the tumor: a solid one and a multilobular cystic component. (18)F-FDG PET imaging revealed an increased uptake in the ischium. The (18)F-FDG uptake resembled the results observed in malignant bone tumors. A histological diagnosis of chondroblastoma was obtained from tissue of an open biopsy. An immunohistochemical analysis demonstrated weak expression of both Glut-1 and HK-II. These findings suggest that Glut-1 and HK-II expression are not strongly related to FDG uptake in chondroblastoma.

Imaging of periosteal reactions associated with focal lesions of bone

Periosteal reaction (PR) is the response of cortical bone to an underlying insult. It is manifest in a limited number of histological and radiological patterns. Although not specific for a particular diagnosis, the appearance of PR aids the radiological characterization of bone lesions. Once ossified, PR is demonstrated well on plain radiography but can also be visualized on ultrasound, CT, MRI and bone scintigraphy, particularly in the early stage. This article provides a pictorial review of the patterns of PR with particular reference to bone tumours.

Subungual chondroblastoma in a 9-year-old girl

Chondroblastoma is an uncommon primary bone tumor, mainly found in the epiphyses of long bones. We describe a 9-year-old girl who presented with a chondroblastoma as a subungual mass in the fifth toe. Radiographs showed an expansive, calcified tumor of the distal phalanx. Histologic examination after excision revealed chondroid differentiation, active mitosis, multinucleated giant cells, calcification, and necrosis. There was no recurrence of the lesion after surgical excision. The purpose of this report is to document this unusual event that occurred in such a short bone as the distal phalanx of the fifth toe, mimicking a dermatologic entity.

Clear cell chondrosarcoma: radiographic, computed tomographic, and magnetic resonance findings in 34 patients with pathologic correlation

OBJECTIVE

To describe the radiographic features of clear cell chondrosarcoma (CCCS), including the computed tomographic (CT) and magnetic resonance (MR) findings, and to correlate them with the histopathologic findings.

DESIGN AND PATIENTS

A retrospective review was carried out of 72 patients with histopathologically confirmed CCCS. Imaging studies were available for 34 patients: conventional radiographs (n=28), CT scans (n=14), and MR images (n=15). Radiographic studies were reviewed by three radiologists who rendered a consensus opinion; the studies were correlated with the histopathologic findings.

RESULTS

Of the 34 patients with imaging studies, 30 were male and 4 were female (mean age 38.6 years; range 11-74 years). Twenty-two lesions were in long bones (15, proximal femur; 1, distal femur; 1, proximal tibia; 5, proximal humerus) and 11 were in flat bones (5, vertebra; 4, rib; 1, scapula; 1, innominate). One lesion occurred in the tarsal navicular bone. Typically, long bone lesions were located in the epimetaphysis (19/22) and were lucent with a well-defined sclerotic margin and no cortical destruction or periosteal new bone formation. More than one-third of the long bone lesions contained matrix mineralization with a characteristic chondroid appearance. Pathologic fractures were present in six long bone lesions (4, humerus; 2, femur). Lesions in the proximal humerus were more likely to have indistinct margins (4/5) and extend into the diaphysis. Flat bone lesions were typically lytic and expansile and occasionally demonstrated areas of cortical disruption. Typically, matrix mineralization, when present, was amorphous. MR imaging, when available, was superior to conventional radiographs for demonstrating the intramedullary extent of a lesion as well as soft tissue extension. CT images better delineated the presence of cortical destruction and the character of matrix mineralization patterns. CCCS lesions were typically low signal intensity on T1-weighted images and moderately or significantly bright on T2-weighted images. Areas of lesion heterogeneity on T1- and T2-weighted images and on post-gadolinium T1-weighted images corresponded pathologically to areas of mineralization, intralesional hemorrhage, and cystic changes. Adjacent bone marrow edema was typically absent (12/15) or only minimally observed in a few cases (3/15). No cases examined with MR imaging demonstrated periosteal new bone formation.

CONCLUSIONS

CCCS typically presents radiographically as a geographic lytic lesion located in the epimetaphyseal region of long bones. Most commonly lesions are found in the proximal femur, followed by the proximal humerus. Lesions within the proximal humerus may exhibit more aggressive features. Lesions in the axial skeleton are typically expansile and destructive, often with soft tissue extension and lack of mineralization. MR imaging may show the presence or absence of bone marrow edema.