Magnetic resonance imaging of intraosseous lipomas: a radiologic-pathologic correlation

Intraosseous lipoma of the patella: a case report and review of the literature

An intraosseous lipoma is considered one of the rarest primary bone tumors. The etiology of this lesion remains unclear; many lesions are asymptomatic and appear only as incidental findings during routine radiographic evaluations. Magnetic resonance imaging of intraosseous lipomas can help to establish a diagnosis and to stage the neoplasm. This is a case report of a 53-year old man with a rare intraosseous lipoma of the patella.

Multiple Infiltrative Intraosseous Lipomas in the Appendicular Skeleton of a Rose-breasted Cockatoo (Eolophus roseicapilla) with a Humeral Fracture

A 9-year-old female rose-breasted cockatoo (Eolophus roseicapilla) was presented for a humeral fracture. At presentation, the bird was severely lethargic and obese. On physical examination, an open right humeral fracture, healed left ulnar fracture, and intertarsal joint swelling were present. Results of hematologic testing and biochemical analysis revealed severe leukocytosis with heterophilia and increased creatine kinase and aspartate aminotransferase activities consistent with musculoskeletal lesions. Radiographs confirmed a right humeral fracture and showed severe polyostotic lytic and expansile lesions of the appendicular skeleton, as well as an enlarged hepatic silhouette. Surgical repair of the fracture was attempted, but the bird died during the procedure. Postmortem examination revealed severe bone deformities involving the fractured humerus, both ulnas, and the left tibiotarsus. Histologic findings were consistent with multiple intraosseous lipomas of the long bones and severe hepatic lipidosis. To our knowledge, this is the first report of multiple intraosseous lipomas in a bird.

Vertebral Body Lipoma: An Unusual Pathology Treated With Kyphoplasty

STUDY DESIGN

Case report.

OBJECTIVE

This case report is unique since this is the first vertebral lipom case that was treated by kyphoplasty alone.

SUMMARY OF BACKGROUND DATA

Vertebral lipoma is extremely rare and our search of the English literature has revealed 20 patients in 16 reports.

METHODS

A 32-year-old female patient was admitted to our neurosurgery department with the chief complaint of low back pain that had lasted nearly 1 year. A lumbar MR suggested a hemangioma and the patient was operated on.

RESULTS

On microscopic examination, the lesion was seen to have a widely infiltrating appearance of mature fat tissue between bone trabeculae diagnosis was intraosseous lipoma.

CONCLUSION

We believe that the management should be surgical total removal of the lesion even in incidentally found cases in order to obtain histologic diagnosis and pain relief.

LEVEL OF EVIDENCE

5.

Sacral intraosseous lipoma: a case report

Sacral tumors are one of the most challenging lesions of the spine to study and manage. Surgical resection techniques are often difficult due to the regional anatomy, in addition to tumor involvement of neural and structural elements. The surgical goals are influenced by tumor pathology but this can be made more complicated by a difficult diagnostic process. The authors present the rare entity of a sacral lipoma and the radiological and histological features which highlight this condition.

Surgical Treatment of Confirmed Intraosseous Lipoma of the Calcaneus: A Case Series

Intraosseous lipoma of the calcaneus is a benign lesion formed by mature adipose tissue. When the lesion is symptomatic, the most frequent presentation is localized pain and soft tissue swelling. Because these lesions can regress spontaneously, conservative treatment methods are recommended. Operative excision is mostly required for painful lesions and pathologic fractures. The data from 14 patients with calcaneal intraosseous lipoma, who had undergone surgery in our clinic, were evaluated retrospectively. Using Milgram's classification system, 9 lesions were classified as stage 1, 4 as stage 2, and 1 as stage 3. All lesions were occupying 100% of intracalcaneal cross-section in the coronal plane and >30% in the sagittal plane of magnetic resonance imaging sections. The mean preoperative visual analog scale score was 5.29 ± 1.14 (range 4 to 7), and the mean postoperative visual analog scale score at the last follow-up visit was 1.14 ± 0.36 (range 1 to 2), which was significantly better (p < .01). The mean Maryland foot score at the last follow-up visit was 97.71 ± 2.02 (range 95 to 100). The mean American Orthopaedic Foot and Ankle Society Ankle-Hindfoot scale score was 97.86 ± 2.11 (range 94 to 100) at the last follow-up visit. The differences between the pre- and postoperative values were statistically significant (p < .01). No recurrence had been detected within a median follow-up period of 84 months. Operative management of symptomatic lesions related to intraosseous lipoma of the calcaneus provides better results compared with the preoperative state.

A rare case of intraosseous fibrolipoma of the mandible: diagnosis and treatment

Lipomas are common soft tissue tumors. Intraosseous lipoma is a rare lesion that constitutes not more than 0.1% of bone tumors. It can occur anywhere in the body and there have only been a few cases found in the mandible. Intraosseous fibrolipoma of the jaw is an uncommon histological variant of the classic lipoma and to the best of our knowledge only one case has previously been reported in the literature. The cause of this lesion is uncertain. Clinically the lesion is generally asymptomatic and its radiographic feature is a well-defined radiolucency. Surgery is the treatment of choice. We present a case of an intraosseous fibrolipoma in the right mandibular ramus in a 25-year-old female.

Intraosseous Lipoma of the Femor: Image Findings

INTRODUCTION

Intraosseous lipoma is a rare benign bone disease. Long and cancellous bones are the most locationsthat can be affected. Almost all lesions were discovered incidentally on imaging modalities that were done during an unrelated investigation. As it is rare, it may be mistaken for nonossifying fibroma, aneurismal bone cyst, simple bone cyst, bone infarct or chondroid tumors. Recently with the high quality imaging modalities such as CT scan and/or MR imaging, the diagnosis of intramedullary lipoma and some other bone lesions can be done without the need for bone biopsy and surgery.

CASE REPORT

We're reporting a rare case of intraosseous lipoma of the distal femur. Plain film radiography showed barely visible medullary expansion and lucency in the distal left femoral diaphysis. The patient underwent further evaluation with computed tomographic (CT) and magnetic resonance Imaging (MRI). According to the MRI and CT scan findings, intraosseous lipoma was confirmed and the need for more diagnostic tests were eliminated.

CONCLUSION

Although Intraosseous lipoma doesn't have any manifestations clinically but it should be considered in the differential diagnosis of bone pains. MRI has an important role in characterization of soft tissue and bone marrow lesions therefore non-surgical approach for most of the patients with intraosseous lipoma would be beneficial.

Intraosseous lipoma of the calcaneus: report of a case and review of the literature

Intraosseous lipoma is a rare, benign primary tumor occurring in bone. In the present report, a case of an intraosseous lipoma of the calcaneus is presented, together with a focused review of published studies. Radiographically, the lesions will appear osteolytic and well delineated, displaying a central area of calcification. Curettage and packing with autogenous bone grafts was our treatment for this rare tumor. In the present case, and 1 previously published case, a central sclerotic mass was observed. The histologic findings were typical, with mature adipose tissue mixed with a few degenerated bone trabeculae.

An unusual cause of a cystic lesion with an osteochondral defect in the talus: intraosseous lipoma

An intraosseous lipoma is a rare benign bone lesion that proliferates from mature lipocytes. It occurs most frequently in the lower limb, particularly in the calcaneus. The talus is an unusual location for this rare lesion. A review of the literature produced only two reports with talar intraosseous lipomas under the name of intraosseous lipomatosis, which described multiple lipomas in different areas. We describe a 38-year-old male patient who had an isolated intraosseous lipoma with an osteochondral defect in the talus and was treated with autologous osteochondral graft transplantation by medial malleolar osteotomy. He could walk with full weightbearing without any assistance at the end of 12 months. Intraosseous lipoma localized in the talus may be confused radiologically with other bone lesions, especially with unicameral bone cyst, if it is associated with an osteochondral defect. Autologous osteochondral graft transplantation is a successful treatment method for talar intraosseous lipoma.

Surgery is not always necessary in intraosseous lipoma

Intraosseous lipoma is the rarest primary bone tumor, is usually asymptomatic, and is often discovered incidentally during unrelated investigations. Lipomas usually undergo varying degrees of involution, with necrosis, cyst formation, and calcification. Careful radiological-pathological correlation is required to avoid misinterpretation. This study describes 12 intraosseous lipomas in 11 patients (6 men, 5 women; mean age, 36 years [range, 25-50 years]; mean follow-up, 5 years [range, 2-11 years]). The lesions were located in the calcaneus in 7 patients (bilaterally in 1 patient), the tibia in 2, the femur in 1, and the ilium in 1. All lesions were asymptomatic and discovered incidentally except in 4 patients (5 lesions). Curettage and bone grafting were performed after biopsy in 4 lesions; and in 1 patient, curettage, bone grafting, and reconstructive surgery were performed after pathologic fracture. The remaining 7 patients were followed up conservatively. Although definite diagnosis of an intraosseous lesion is possible only by histopathologic examination, computed tomography and magnetic resonance imaging findings of intraosseous lipoma are typical, and most patients' symptoms are relieved by conservative means. For this reason, we believe that in patients with no signs of an impending pathologic fracture or suspicion of malignancy, clinical and radiological follow-up is sufficient. However, since intraosseous lipoma is an uncommon bone tumor, physicians should be familiar with the radiological features of this lesion for the correct diagnosis.

Intraosseous lipoma in the femoral shaft mimicking a bone metastasis on bone scintigraphy

Primary intraosseous lipoma is a rare benign neoplasm of mature fat cells arising within the bone marrow, most commonly within the metaphysis of long bones. Involvement of the epiphysis or diaphysis is uncommon. An intraosseous lipoma typically shows no abnormal uptake of a bone-seeking agent. Bone scintigraphy demonstrated a focal area of uptake in the right femoral shaft mimicking a bone metastasis in a 52-year-old man with basal cell carcinoma of the face. Plain radiography showed a well-defined radiolucent lesion with endosteal erosion in the intramedullary portion. MRI showed no fat tissue in the lesion. Histology confirmed intraosseous lipoma with dystrophic calcification and myxomatous degeneration.

Intraosseous lipoma. A clinical, radiologic, and pathologic study of 5 cases

Intraosseous lipoma is an uncommon tumor of bone with indistinct radiologic features that makes it diagnostically challenging to radiologists and pathologists. There is a need to familiarize these physicians with the radiographic and pathologic features of this lesion for the correct diagnosis. We described the radiologic and pathologic features of intraosseous lipoma in 5 women. In 4 patients, the tumors occurred in long bones, whereas in the fifth patient, the skull was involved. Patients' age ranged from 50 to 63 years. Plain radiographs of the long bones revealed well-circumscribed benign-appearing osteolytic lesions with sclerotic margins, whereas in the skull, a poorly defined lytic aggressive-looking lesion was observed. In the long bones, the lesions showed remodeling of the affected bone with matrix calcification, simulating bone infarcts. Microscopically, mature adipose tissue with fat necrosis, absence of hematopoietic elements, and dystrophic calcification corresponding to the calcified matrix seen on the plain radiographs were seen. The osteolytic skull lesion had large caliber thin-walled vasculature with occasional fibrin thrombi mimicking intramuscular hemangiomas of soft tissue. On plain radiographs, an intraosseous lipoma is usually seen as a rather benign-appearing osteolytic bone lesion with well-defined margins and a heavily calcified/ossified dense matrix. Plain radiographs alone cannot establish the diagnosis of intraosseous lipoma as it mimics several other benign and malignant bone lesions. Intraosseous lipoma often contains calcified necrotic fat with little mature adipose tissue and characteristically induces expansion/remodeling of the affected bone.

From the archives of the AFIP: benign musculoskeletal lipomatous lesions

Benign lipomatous lesions involving soft tissue are common musculoskeletal masses that are classified into nine distinct diagnoses: lipoma, lipomatosis, lipomatosis of nerve, lipoblastoma or lipoblastomatosis, angiolipoma, myolipoma of soft tissue, chondroid lipoma, spindle cell lipoma and pleomorphic lipoma, and hibernoma. Soft-tissue lipoma accounts for almost 50% of all soft-tissue tumors. Radiologic evaluation is diagnostic in up to 71% of cases. These lesions are identical to subcutaneous fat on computed tomographic (CT) and magnetic resonance (MR) images and may contain thin septa. Lipomatosis represents a diffuse overgrowth of mature fat affecting either subcutaneous tissue, muscle or nerve, and imaging is needed to evaluate lesion extent. Lipoblastoma is a tumor of immature fat occurring in young children, and imaging features may reveal a mixture of fat and nonadipose tissue. Angiolipoma, myolipoma, and chondroid lipoma are rare lipomatous lesions that are infrequently imaged. Spindle cell and pleomorphic lipoma appear as a subcutaneous lipomatous mass in the posterior neck or shoulder, with frequent nonadipose components. Hibernoma appears as a lipomatous mass with serpentine vascular elements. Benign lipomatous lesions affecting bone, joint, or tendon sheath include intraosseous lipoma, parosteal lipoma, liposclerosing myxofibrous tumor, discrete lipoma of joint or tendon sheath, and lipoma arborescens. Intraosseous and parosteal lipoma have a pathognomonic CT or MR appearance, with fat in the marrow space or on the bone surface, respectively. Liposclerosing myxofibrous tumor is a rare intermixed histologic lesion commonly located in the medullary canal of the intertrochanteric femur. Benign lipomatous lesions may occur focally in a joint or tendon sheath or with diffuse villonodular proliferation in the synovium (lipoma arborescens) and are diagnosed based on location and identification of fat. Understanding the spectrum of appearances of the various benign musculoskeletal lipomatous lesions improves radiologic assessment and is vital for optimal patient management.

Osseous lesions of the pelvis and long tubular bones containing both fat and fluid-like signal intensity: an analysis of 28 patients

PURPOSE

The purpose of this study was to explore the nature of lesions in the pelvis and the long tubular bones that, with MR imaging, were found to contain both fat and fluid-like signal intensity and to correlate these findings with those of radiography, histologic analysis, and clinical and radiographic follow-up.

MATERIALS AND METHODS

A retrospective review of the radiologic, clinical and histologic parameters of 28 patients with lesions in the pelvis and long tubular bones comprised of elements that demonstrated both fat and fluid signal intensity characteristics by MR imaging was performed. Several parameters were analyzed. Histologic analysis was available in 12 patients. Clinical and, or imaging follow-up was available in 13 patients.

RESULTS

Imaging and histologic findings suggested the presence of fat and fluid and fluid components in all lesions with which could be divided into distinct MR imaging patterns. Histologic analysis suggested the possibility of a shared pathogenesis among several different lesions.

CONCLUSION

All lesions of the long tubular bones in our series revealing both fat and fluid-like signal intensities with MR imaging were nonaggressive on the basis of other imaging findings, follow-up assessment, histologic analysis, or combinations of the three. Histologic findings suggest a relationship among lipomas, fat necrosis and cystic infarct of bone.

Intraosseous lipoma: retrospective analysis of 29 patients

We reviewed 29 patients with intraosseous lipoma treated between 1985 and 2002. Mean patient age was 48 (20-75) years. According to Milgram's classification, ten cases were classified as stage I, 14 as stage II, and three as stage III. All patients were initially treated by curettage. In 11 cases an additional phenolization was performed. The average follow-up was 32 (6-208) months. At the last follow-up, none had any clinical or radiological signs of recurrence. The adequate treatment of a symptomatic intraosseous lipoma is curettage and bone grafting. In the current study, phenolization showed no added benefit. An asymptomatic intraosseous lipoma without impending pathological fracture can be treated conservatively.

[Surgical indications in intraosseous lipoma of the calcaneus. Case report and critical review of the literature]

Intraosseous lipomas represent a small number of benign bone tumors with incidence rates of approximately 0.1%. In about 15% these neoplasias are localized within the calcaneus, mostly at Ward's triangle. The tumors usually remain clinically inapparent and diagnosis is often obtained incidentally. Although CT scan and MRI provide specific and sensitive diagnostic tools that can distinguish morphology and dignity, surgical treatment is not standardized yet. In conjunction with a case report, we summarize and critically compare current treatment strategies.

Intraosseous lipoma of lamina of the first thoracic vertebra: a case report

STUDY DESIGN

A case is reported.

OBJECTIVE

To report a case of intraosseous lipoma involving the lamina of the first thoracic vertebra.

SUMMARY OF BACKGROUND DATA

Intraosseous lipomas involving the spine rarely have been reported.

METHODS

An incidental intraosseous lesion of the lamina of the first thoracic vertebra documented on magnetic resonance imaging was surgically excised and pathologically evaluated.

RESULTS

The histologic findings were consistent with those for intraosseous lipomas previously reported in other bones.

CONCLUSIONS

The authors present a rare case of an intraosseous lipoma involving the lamina of the first thoracic vertebra.

Intraosseous lipoma: report of 35 new cases and a review of the literature

OBJECTIVE

To identify the common imaging features of intraosseous lipomas on radiographs, magnetic resonance imaging (MRI) and computed tomography (CT), and review their histological features.

DESIGN AND PATIENTS

Thirty-five previously unreported cases of intraosseous lipoma were reviewed and a meta-analysis was performed of another 110 cases identified from the English language literature.

RESULTS

The mean age at presentation is 43 years. Sex distribution is nearly equal. Lipomas occur most frequently in the lower limb (71% overall), particularly in the os calcis (32%). Other common sites include the metaphyses of long bones, where lesions are typically eccentric. Lipomas are usually well defined, but marginal sclerosis is commoner in lesions of the os calcis (61%) than at other sites (38%). Calcification is also more frequent in the os calcis (62%), and almost invariably centrally located. Calcification at other sites is less common (30%), and is more variable in appearance. Bone expansion is less common (30%), and usually minimal. Fat necrosis and cyst formation identified on MRI is common (67%), and more frequent in the os calcis.

CONCLUSIONS

Although there is correlation between the histological and radiological features of intraosseous lipomas in general, some discrepancies occur in the radiological appearances of lipomas in different sites. The evidence that these lesions are true benign tumours of fat is controversial. Several aetiological factors have been implicated in their development. The constant location of os calcis lesions at the critical angle suggests an aetiology that may be related to biomechanical lines of stress. In other instances it is possible that involution of pre-existing lesions may lead to the development of lipomas.

Radiologic case study. Benign intraosseous lipoma

Intraosseous lipomas are uncommon lesions of bone most often diagnosed incidentally. They typically manifest a classic radiographic appearance, but CT or MRI may be useful in diagnosing lesions that are atypical or incompletely defined radiographically and avoid an unnecessary biopsy.

Intraosseous lipoma: a clinical study of 12 patients

We studied 12 patients (13 bones) with intraosseous lipoma to elucidate the clinical features of this disease. The patients ranged in age from 14 to 54 years. Eleven patients were men and 1 was a woman. The involved bones were the calcaneus in 6 patients (7 bones), humerus in 3, ischium in 2, and sacrum in 1. Three bones were in Milgram's stage I, 8 were in stage II, and 2 were in stage III. On plain radiographs, all bones showed a well-circumscribed radiolucent area. Nine bones showed calcification or ossification. Computed tomography or magnetic resonance imaging showed low density or high signal intensity, respectively, identical to the findings in normal adipose tissue. The tumor was curetted in 3 patients (3 bones), in whom local recurrence was not seen thereafter. In the remaining 9 patients (10 bones), we observed the natural course; in 1 of these patients, incisional biopsy was performed. During the follow-up period, only 1 patient showed slight enlargement of the lesion, while the findings in the others remained unchanged. Three patients had pain, which disappeared after the surgery or during the course of the observation. Partly because intraosseous lipoma tends to undergo spontaneous involution, and partly because diagnosis is easy from the radiological findings, surgery does not seem to be necessary in most patients.

Involuted intraosseous lipoma of the sacrum showing high signal intensity on T1-weighted magnetic resonance imaging (MRI)

Involuted intraosseous lipoma with extensive fat necrosis resulting in cyst formation (Milgram stage III) is distinguishable from lesions without necrosis (stage I) or lesions with focal fat necrosis (stage II), based on differences in signal intensity on magnetic resonance imaging (MRI). Fat tissue has a high signal intensity on both T1- and T2-weighted MR images, whereas the extensive fat necrosis that results in cyst formation shows high signal intensity on T2-weighted images and low intensity on T1-weighted images. We report a patient in whom an intraosseous lipoma with high signal intensity on both T1- and T2-weighted MRI was found to be extensively involuted on histopathologic examination. Intraosseous lipoma appears to undergo spontaneous involution. In some patients, therefore, surgical excision may not be necessary. A correct preoperative diagnosis should reduce the necessity for a biopsy or surgery. Although lesions classified as stage I or II are easily identified by MRI, those of stage III are difficult to diagnose preoperatively by this method.

Intraosseous lipoma of the calcaneus

We present two patients with pathologically proven intraosseous lipoma of the os calcis. A review of the literature, the radiologic criteria, and the differential diagnosis are provided.