Activating Gs α mutation at the arg201 codon in liposclerosing myxofibrous tumor

Liposclerosing myxofibrous tumor of the distal femur: A case report

Introduction

Liposclerosing myxofibrous tumor (LSMFT) is a rare benign fibro-osseous tumor that most frequently occurs in the proximal femur. The reported literature shows that the proximal femur, ilium, tibia, humerus, rib, and skull have occurred, but so far, the female distal femur has not been characterized in detail. This, we think, is the first single comprehensive case report of the female distal femur. To prevent misdiagnosis and overtreatment of this illness, it is critical for us to continue strengthening our knowledge of it and to add it to the differential diagnosis of the space-occupying lesion of the female distal femur.

Case summary

Two months ago, a 55-year-old female patient was found to have a space-occupying lesion of the left distal femur and the pain symptom was aggravated. She underwent thorough curettage and bone grafting without additional treatment to relieve the current symptoms and determine the nature of the lesion in our hospital. The intraoperative specimens were submitted to the pathology laboratory for analysis, and the result was reported as LSMFT. And six months after the operation, the patient returned to our hospital for another x-ray examination and we found that she had recovered well without any signs of recurrence. The patient self-reported that she had now resumed her daily life without any uncomfortable symptoms.

Conclusion

The incidence of LSMFT itself is relatively low, and the occurrence of the distal femur is even rarer. However, it is recommended to add LSMFT into the differential diagnosis of the occupying lesions of the distal femur. Once the diagnosis is made, thorough curettage and bone grafting without additional special treatment can achieve better postoperative outcomes. The patient gave her agreement after learning that information about the case will be submitted for publication.

Undifferentiated Pleomorphic Sarcoma Arising in a Fibrous Dysplasia Confirmed by GNAS Mutation Analysis: A Case Report

CASE

We report the case of a 78-year-old woman with undifferentiated pleomorphic sarcoma (UPS) of the proximal femur arising in a previous site of fibrous dysplasia (i.e., a liposclerosing myxofibrous tumor) that had been treated 4 years earlier with curetted surgery. GNAS mutation was detected in both the previous benign lesion and the UPS.

CONCLUSION

Genetic analysis is useful in demonstrating the origin of the tumor especially in fibrous dysplasia with severe degeneration that have undergone malignant transformation.

Liposclerosing Myxofibrous Tumor in a Patient with Prostate Cancer: A Case Report

CASE

A 64-year-old man diagnosed with prostate cancer was incidentally found to have a lesion in his distal femur. Although initially concerning for metastatic prostate cancer, after biopsy by an orthopaedic oncology specialist, a diagnosis of liposclerosing myxofibrous tumor (LSMFT) was confirmed. The lesion was treated with curettage and demineralized bone matrix grafting with close follow-up.

CONCLUSIONS

This case report illustrates that LSMFT is not confined to the proximal femur and highlights the differences in radiographic appearance between LSMFT and more common metastatic bone lesions.

Liposclerosing Myxofibrous Tumor: A Review

Liposclerosing myxofibrous tumor is a benign fibro-osseous lesion, with distinct radiographic and clinical features and diverse histologic patterns. This lesion occurs in the fourth decade of life, with equal male and female incidence. Most lesions are discovered incidentally, but patients can present with bone pain or fracture. Liposclerosing myxofibrous tumor exhibits a very strong predilection for the proximal femur with characteristic radiographic findings, often providing an initial clue to diagnosis. Microscopically, this tumor is characterized by a variety of patterns, including myxofibrous tissue, fibrous dysplasia-like features, and ischemic ossification. It can be mistaken for many other fibro-osseous lesions; therefore, this unique lesion should be included in the differential diagnosis of fibro-osseous lesions, particularly in this location. Patients with this lesion are generally successfully treated by curettage and bone graft and have a favorable prognosis. A small risk of malignant transformation has been suggested to be associated with these lesions. This necessitates the need for follow-up monitoring of this entity. In this review, we discuss current knowledge of this lesion and its clinical relevance.

Expression and regulation of amphiregulin in Gsα-mutated human bone marrow stromal cells of fibrous dysplasia of mandible

OBJECTIVES

Fibrous dysplasia (FD) is a focal bone lesion composed primarily of immature bone marrow stromal cells along with spicules of immature woven bone. However, cellular differentiation and proliferation in mutant human bone marrow stromal cells (hBMSCs) of FD have not been fully elucidated. Therefore, the aim of this study was to investigate the occurrence of G(s)α mutation at the Arg(201) codon in hBMSCs and human trabecular bone cells (hTBCs, osteoblast-like cells). In addition, we evaluated the gene expression and protein secretion of amphiregulin from hBMSCs and hTBCs and assessed the biologic activity and possible mechanism of amphiregulin in our system.

STUDY DESIGN

Mutant hBMSCs from FD patients and hTBCs from disease-free bone specimens of the same patient were successfully cultured. We studied the G(s)α mutations at the Arg(201) codon by means of polymerase chain reaction (PCR)-restriction fragment length polymorphism. Gene expression and protein secretion of amphiregulin in hBMSCs and hTBCs was confirmed by reverse-transcription (RT) PCR and Western blotting analysis. The modulation proliferation and possible mechanism of the exogenous addition of amphiregulin and epidermal growth factor receptor tyrosine kinase inhibitor (AG-1478) were assessed by using Wst-1 assays.

RESULTS

The G(s)α mutations in clonal adherent mutant hBMSCs and hTBCs were successfully identified. We identified amphiregulin to be highly expressed in hBMSCs compared with hTBCs. The growth of hBMSCs was stimulated by the exogenous addition of amphiregulin and inhibited by AG-1478.

CONCLUSIONS

The G(s)α-mutant hBMSCs were successfully identified, and amphiregulin may play a significant role in the proliferation of hBMSCs.

Case report: two-step malignant transformation of a liposclerosing myxofibrous tumor of bone

We present the case of a patient with malignant transformation of a liposclerosing myxofibrous tumor. The patient had a histologically confirmed liposclerosing myxofibrous tumor that, during a course of 22 months, spontaneously transformed into a lesion appearing like a benign giant cell reactive lesion and subsequently into a high-grade bone sarcoma. Few such cases of spontaneous malignant transformation of liposclerosing myxofibrous tumor have been reported. We report what we believe to be the first case documenting spontaneous transformation of a liposclerosing myxofibrous tumor into an intermediate lesion with benign-appearing histologic features and then into a high-grade malignant tumor.

Monostotic fibrous dysplasia of the proximal femur and liposclerosing myxofibrous tumor: which one is which?

Clinical, histological, and genetic studies of two cases of isolated fibro-osseous lesions of the femur in adults show the overlap between monostotic fibrous dysplasia (MFD) of the proximal femur and the so-called liposclerosing myxofibrous tumor. The two cases highlight how the incomplete understanding of the natural history of MFD may result in diagnostic pitfalls or incorrect classification of individual lesions.

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.