A 48-year-old female patient was admitted to our hospital with left thigh and hip pain. The patient presented for the first time 26 years ago with similar complaints and was followed up by orthopaedics. The patient didn’t undergo any surgical operation and has no known malignancy and other diseases.
Plain X-ray, MRI, and sonographic images of lesions obtained for further evaluation. In plain X-Ray images at the left iliac bone and proximal femur, there were regions of increased radiolucency, with ground glass appearances, expansive features, with well-demarcated contours, endosteal remodelling, but no bone destruction, and no periosteal reaction (figure 1a and 1b). Also, there was a lesion in the left iliac bone which is surrounded by a layer of thick, sclerotic reactive bone ("rind sign").
MRI images of bone and soft tissue lesions were shown in Figures 2 and 3 respectively. MRI images showed heterogeneous masses with sharply demarcated borders and cystic degenerations in medullary regions of the iliac bone and proximal femur with minimal enhancement. Bone lesions remained the same in size and there was a gradual but little increase in the size of cystic mass (5.5 cm to 7.3 cm in four years). Also, there was a complex cystic soft tissue mass with peripheral enhancement within proximal fibres of the rectus femoris muscle. In figure 4, sonographic images of myxoma are demonstrated. Ultrasound-guided biopsy was taken from the soft tissue lesion and histologically confirmed that the lesion was a myxoma.
Mazabraud’s Syndrome is a rare syndrome with a prevalence of 1/1.000.000 [1]. The disease has a predilection of females (68-84%) [2]. The syndrome is characterized by cystic soft tissue masses (myxoma) accompanied by fibrous dysplasia and cystic lesions are usually located near the bony component. Fibrous dysplasia usually appears in the polyostotic form, but monostotic forms could also be encountered [3]. It may present with pain, skeletal deformity and, pathological bone fractures. The syndrome was reported to be associated with postzygotic GNAS1 gene mutations involved in cell proliferation [4].
Because of increasing size at later ages, myxomas may present as painful or painless palpable masses. Ultrasound provides important information for lesions that are superficial enough for sonographic imaging. On sonography, myxomas are seen as septated cystic lesions with a thick wall and dense content in the deep subcutaneous fat tissue and between muscle fibres. On MRI, myxomas demonstrate hypointense T1WI, homogeneous hyperintense T2WI signal, and poor wall enhancement after contrast administration can be seen. In these patients, fibrous dysplasia is usually detected incidentally on imaging. Fibrous dysplasia can develop in different localizations within the axial and appendicular skeleton such as femur, humerus, ribs, and skull [5]. Expansile masses with a ground-glass appearance on direct radiography are typical findings for fibrous dysplasia. At the bone lesions, MRI can demonstrate hyperintense cystic, hemorrhagic, or fatty areas on T2WI and hypointense signal changes in all sequences due to fibrocartilage tissues and calcifications. Heterogeneous or peripheral rim enhancement is generally expected in contrast-enhanced sequences [4]. Fibrous dysplasias are benign tumours that are classified as "Don't touch" bone tumours and pose a risk of pathological fracture, therefore, in addition to other radiological findings, FDG/PET imaging and biopsy findings (focused on the confirmation of myxomas) could be helpful for proving the diagnosis.
Lesions should be followed up radiologically and clinically. Pathological fractures, development of new myxoma, and (although rare) sarcomatous transformation in bony lesions can be seen during follow-up. In the case of sarcomatous transformation in fibrous dysplasia, the patient may present with symptoms such as pain and swelling [6]. In this case, the diagnosis should be confirmed by biopsy and the patient should be referred for appropriate surgical intervention (curettage or excision).
In summary, Mazabraud Syndrome should be suspected if cystic soft tissue lesions are found in combination with fibrous dysplasia. It should be known that the lesions that develop due to this syndrome are benign and should be followed clinically and radiologically. Radiologists should be aware that pathological fractures, newly developing or enlarging myxomas may be seen during follow-up, and sarcomatous transformation may develop in bony lesions.
Mazabraud’s Syndrome
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Based on the provided X-ray and MRI images, the following main features can be observed:
• Bone changes: A “ground-glass” density is observed in the left femur and pelvis, with some areas showing expansile changes and irregular morphology, suggesting fibrous dysplasia (fibrous abnormal proliferation).
• Soft tissue lesions: In the left iliopsoas region and the intermuscular spaces of the thigh, there are septated, cystic signals or hypoechoic lesions (visible on MRI and ultrasound). Some areas may appear septated or have slightly thick walls with denser internal content. On MRI, T1 appears low signal, T2 appears high signal, and enhancement mainly shows mild or marginal enhancement, consistent with common features of myxoma.
• No clear fracture lines or obvious discontinuity of the cortical bone are seen (based on current images, although there is a need to be vigilant about potential pathological fractures in the regions with fibrous dysplasia).
• No significant erosive features are noted in nearby joints and soft tissues, and no obvious signs of malignancy are noted at this time.
Taking into account the patient's history (long-term recurrent discomfort in the left thigh and hip, no previous surgeries, and no other known malignancies) and the imaging findings, the following potential or differential diagnoses are considered:
Based on the patient’s history (previous occurrences of similar symptoms, middle-aged female), imaging findings (multiple fibrous dysplasia-like changes and adjacent intramuscular myxoma-like lesions), and the pathogenesis described in the literature, the most likely diagnosis is Mazabraud syndrome.
There is currently no direct imaging evidence suggestive of malignant transformation; however, close follow-up is necessary to rule out any rare sarcomatous change. If new suspicious findings emerge (e.g., a rapid increase in lesion size or significantly worsened pain), biopsy or further imaging (such as PET/CT) should be considered to clarify the diagnosis.
Treatment Strategy:
• Clinical Follow-up: For stable fibrous dysplasia and myxoma lesions, regular follow-up (X-ray or MRI) and symptom management are recommended.
• Surgical Indications: If persistent or significant pain appears, if there is rapid lesion growth, or if the risk of pathological fracture increases, surgical intervention should be considered, including curettage of the lesion, bone grafting, or internal fixation. Myxoma can be surgically excised.
• Conservative/Supportive Therapy: Pain can be managed with analgesics, physical therapy, etc., and additional physiotherapeutic treatments can be used if necessary.
Rehabilitation and Exercise Prescription:
• Basic Principles:
Disclaimer: This report is a reference analysis based on available imaging and medical history and should not replace in-person consultation or professional medical advice. If you experience any discomfort or have questions, please seek medical attention and further examination promptly.
Mazabraud’s Syndrome
