A 36 year old woman previously diagnosed with Mc Cune-Albright's syndrome presented to our hospital complaining of right lower extremity pain while walking.
A 36 year old woman presented to our hospital complaining of right lower extremity pain while walking. She had been diagnosed with McCune-Albright's Syndrome at the age of 8 years. Her disease process had been characterized by early breast development at 5 years of age and menarche at the age of 8. She was quite disfigured with a very big head and external occipital protuberance. She had suffered a leg-length discrepancy with right leg shorter than left since she was 14 but this was the first time she complained of painful walking. She underwent an X-ray skeletal survey which was preceded by a bone scan. The bone scan revealed increased uptake of the radioisotope tracer technetium-99m methylene diphosphonate (99mTc MDP) occuring mainly in skull and facial bones as well as in right pelvis, femur and tibia. On plain radiographs findings of polyostotic fibrous dysplasia were once more recognized. There was an extension of existing lesions and the involved bones showed increasing deformity. New lesions appeared in areas that were previously normal. She also had a skull CT scan in order to estimate the degree of fibrous dysplasia locally.
Mc Cune-Albright syndrome in its classic form consists of at least 2 features of the triad of polyostotic fibrous dysplasia (PFD), café au lait skin pigmentation, and autonomous endocrine hyperfunction (causing precocious puberty and other abnormalities). This condition is similar to the Jaffe-Lichtenstein syndrome, but distinguished from that by the patchy skin pigmentation and sexual precocity. PFD has a broad spectrum of severity. The disease frequently involves the skull and facial bones, pelvis, spine and shoulder girdle. The sites of involvement are the femur (91%), tibia (81%), pelvis (78%), ribs, skull and facial bones (50%), upper extremities, lumbar spine, clavicle, and cervical spine, in decreasing order of frequency. The dysplasia may be unilateral or bilateral, and it may affect several bones of a single limb or both limbs with or without axial skeleton involvement. Two thirds of patients are symptomatic before they are 10 years of age. Often, the initial symptom is pain in the involved limb associated with a limp, spontaneous fracture, or both. Leg-length discrepancy of varying degrees occurs in about 70% of patients with limb involvement. The structural integrity of the bone is weakened, and the weight-bearing bones become bowed. The curvature of the femoral neck and proximal shaft of the femur markedly increase because a femoral lesion commonly causes a severe coxa vara abnormality, shepherd's-crook deformity, which is a characteristic sign of the disease. The usual appearance of fibrous dysplasia includes a lucent lesion in the diaphysis or metaphysis, with endosteal scalloping and with or without bone expansion and the absence of periosteal reaction. Usually, the matrix of the lucency is smooth and relatively homogeneous; classically, this finding is described as a ground-glass appearance. The craniofacial pattern of the disease occurs in 50% of patients with the polyostotic form of fibrous dysplasia. Sites of involvement most commonly include the frontal, sphenoid, maxillary, and ethmoidal bones. The occipital and temporal bones are less commonly affected. The frontal bone is involved more frequently than the sphenoid, with obliteration of the sphenoid and frontal sinuses. The skull base may be sclerotic. Single or multiple, symmetric or asymmetric, radiolucent or sclerotic lesions in the skull or facial bones may be present. Distortion of nasal cavities is also present. Plain radiographs are highly specific when characteristic features are present in a lesion. CT scan is extremely useful in evaluating the extent of disease in complex locations such as the facial bones, pelvis, chest wall, and spine. MRI is not often required for diagnosis. Polyostotic lesions occassionally undergo malignant transformation to osteosarcoma,fibrosarcoma or chondrosarcoma. Prevalence of malignant transformation is about 4 %. Rarely PFD is associated with intramuscular myxoma, the so called Mazabraud's syndrome. The relationship between fibrous dysplasia and myxoma remains unclear, but an underlying localized error in tissue metabolism has been proposed. Fibrous dysplasia is difficult to treat effectively. Current therapies focus on the treatment of complications , rather than prevention. Studies using bisphosphonates are promising, although it is unclear if bisphosphonates significantly reduce morbidity associated with these lesions.
Polyostotic Fibrous Dysplasia in Mc Cune-Albright's syndrome
Based on the provided whole-body bone scintigraphy and multiple X-ray and CT scans, the following key features are noted:
1. Multiple Bony Changes: Irregular, “ground-glass” or heterogeneous density changes are visible in the right lower limb (including the femur and tibia), pelvis, skull base, and hands, suggesting multiple fibrous bone lesions.
2. Deformation of Bone Structure: The right femur shows a bending deformity, possibly with a “Shepherd’s crook” appearance, indicating involvement of the femoral neck or proximal region with varying degrees of mechanical axis alteration. The pelvis also exhibits irregular morphology or localized thickening/deformation of the iliac bone.
3. Craniofacial Bone Involvement: CT of the skull base and facial bones reveals multifocal bone thickening or radiolucent lesions with local expansion. Deformations in the frontal bone, sphenoid bone, and maxilla can alter the normal configuration of some sinuses or bony cavities.
4. Heterogeneous Bone Density: Localized sclerotic or radiolucent lesions can be seen in long bones and flat bones, with boundaries showing varying degrees of endosteal sclerosis or irregular bony destruction. No prominent periosteal reaction is identified overall.
5. Subacute/Chronic Lesions: No clear acute fracture lines are observed, but there may be chronic micro-fractures or disrupted trabecular patterns. Awareness of pathological fractures and potential deformities is necessary.
Considering the patient’s history of McCune-Albright syndrome and the imaging features, the following differential diagnoses are suggested:
1. Multiple Fibrous Bone Lesions (Polyostotic Fibrous Dysplasia):
• Typically associated with McCune-Albright syndrome, characterized by the classic “ground-glass” appearance, multiple skeletal involvement, and bone deformities.
• Coexisting endocrine hyperfunction and “café-au-lait” skin pigmentation suggest McCune-Albright syndrome.
2. Jaffe-Lichtenstein Syndrome:
• Presents with multiple or solitary fibrous bone lesions but often lacks the endocrine abnormalities or skin pigmentation seen in McCune-Albright syndrome.
• Imaging findings may be similar to McCune-Albright syndrome, but the clinical manifestations differ.
3. Other Fibrous Dysplastic or Benign Bone Tumors:
• Such as giant cell tumor of bone or enchondroma, but these are typically not distributed so extensively or associated with endocrine findings, and the widespread “ground-glass” pattern is less common.
4. Potential Malignant Transformation (e.g., Fibrosarcoma, Osteosarcoma):
• Although rare, polyostotic fibrous dysplasia can undergo malignant change. Rapid progression, bone destruction, soft tissue mass, or periosteal reaction warrant heightened suspicion. No definite malignant signs are apparent on current imaging.
Based on the patient’s age, known diagnosis (McCune-Albright syndrome), typical imaging features of multiple fibrous bone lesions, and clinical symptoms (pain with ambulation in the right lower limb, bone deformity), the most likely diagnosis is: Polyostotic Fibrous Dysplasia, consistent with McCune-Albright syndrome.
If there are concerns about local malignant transformation or additional pathology, targeted biopsy or follow-up with enhanced CT/MRI can be considered.
1. Treatment Strategies:
• Conservative Management: For patients with mild symptoms and minimal deformity, maintain regular follow-ups to monitor bone metabolic markers and imaging changes. Avoid excessive weight-bearing or trauma.
• Pharmacotherapy: Bisphosphonates (e.g., zoledronic acid) could help alleviate bone pain, but the overall impact on disease progression is uncertain. The effects on bone mineral metabolism must be weighed.
• Surgical Intervention: In cases of severe deformity, recurrent pathological fractures, or uncontrolled pain, consider corrective osteotomy, internal fixation, or surgical decompression/repair if critical structures (e.g., cranial base) are compressed.
• Endocrine Management: Collaborate with endocrinology for hormonal regulation if hyperthyroidism, acromegaly, or other endocrine dysfunctions coexist.
2. Rehabilitation/Exercise Prescription:
• Principles: Gradual, individualized rehabilitation to avoid excessive loading or impact, especially for weight-bearing bones prone to deformity or fracture.
• Initial Phase (FITT-VP):
- Frequency: 3–4 sessions per week of low-impact activities such as swimming, aquatic therapy, or stationary cycling.
- Intensity: Low to moderate, avoiding significant pain.
- Time: About 20–30 minutes per session, potentially divided into shorter intervals.
- Type: Focus on reducing joint stress and bone strain, e.g., swimming, stationary cycling, or partial resistance exercises.
- Progression: Gradually increase training load or incorporate light resistance and core stability exercises as pain improves and bone strength stabilizes.
- Volume: Start from a total of 60–90 minutes per week, increasing slowly.
• Advanced Phase: If lower-limb stability improves and pain subsides, under professional guidance, introduce mild weight-bearing exercises such as slow treadmill walking or stance training, while monitoring for bone pain or progression of deformities.
• Precautions: Avoid high-impact or twisting movements. Ensure adequate calcium and vitamin D intake. Discontinue training and seek medical evaluation if pain worsens or new symptoms arise.
Disclaimer: This report is based solely on current examinations and clinical information for reference purposes and does not replace in-person consultation or professional medical advice. If you have any concerns or changes in your condition, please seek prompt medical attention or further diagnostic evaluation.
Polyostotic Fibrous Dysplasia in Mc Cune-Albright's syndrome
