A 25-year-old man with chest pain. No history of trauma or relevant prior medical history. Chest X-ray was performed. Chest X-ray 5 years before was completely normal.
Chest X-ray (Fig 1) showed an extrapleural density on lateral thoracic wall; rib X-ray (Fig 2) confirmed a lytic expansile lesion on a rib.
Chest MDCT (Fig 3, 4) was performed to define the rib lesion and showed a pathologic fracture associated. The lesion had a heterogeneous density inside but no calcified matrix nor fluid-fluid levels. There were no trabeculations, cortex was not interrupted and there was no soft-tissue mass associated.
At scintigraphy the rib lesion showed increased uptake of radionuclide with no other bone affected.
Surgical excision of the rib was performed because it was symptomatic and has grown over the years.Fibrous dysplasia with focus of aneurysmal bone cyst was histologically demostrated.
Primary bone tumours of the chest wall are uncommon, 95% of these primary tumours are located in the ribs [1].The most frequently benign chest wall lesions are fibrous dysplasia, ostechondroma and enchondroma [1].
Fibrous dysplasia [2] is a developmental bone disease in which there is a medullary replacement by fibrous tissue. There are two forms: monostotic and polyostotic. Monostotic disease can involve any bone and is usually asymptomatic. The most frequent bones affected are: femur, tibia, rib and mandible. Radiologically it appears as a well demarcated lytic lesion, diaphyseal, with a ground-glass inside appearance, endosteal scalloping and expansion are usually present. No treatment is necessary if a typical lesion is recognised. Lesions usually stabilise after puberty. Complications are rare; the most frequent is pathologic fracture.
Aneurysmal bone cyst (ABC) is an expanding lytic lesion that can appear with two forms [3] primary or secondary to other bone lesions: giant cell tumour (the most common), chondroblastoma, chondromyxoid fibroma and fibrous dysplasia. In one third of cases the preexisting lesion can be identified [3]. Over 50% affect long tubular bones and is usually symptomatic with pain and swelling. At imaging ABC are lytic expanding lesions, tend to be localised metaphyseal and eccentric; can be septated and fluid-fluid levels can be present. [2] Surgery is the treatment of choice.
Both fibrous dysplasia and aneurysmal bone cyst are lesions that appear in children and young adults.
TEACHING POINT: It is important to know the association of aneurysmal bone cyst to other bone lesions as fibrous dysplasia, as it can explain the rapid growth of a radiologically benign lesion.
Rib fibrous dysplasia associated with aneurysmal bone cyst
1. The chest X-ray shows a localized expansile lesion of the right (example) rib. The bone exhibits slight osteopenia and lucency, resembling a “ground-glass” appearance, with relatively clear margins.
2. CT scans reveal deformity and widening of the affected rib, with a localized protrusion. The internal density appears heterogeneous, and some areas show septation or cystic expansion.
3. No significant soft tissue mass extending markedly into the thoracic cavity or outward through the chest wall is observed, and there is no obvious sign of bone fracture.
4. Comparison with X-ray images from five years ago, which were normal, indicates that the lesion has increased in size, suggesting gradual growth over time.
Based on clinical presentation (young male, chest pain, no history of trauma) and radiological characteristics (solitary lesion, located in the rib, expansile bone lesion), the following differential diagnoses should be considered:
Considering the patient’s young age, gradual lesion growth, “ground-glass” changes on imaging, and pathological findings, the confirmed diagnosis is: Fibrous Dysplasia with an Aneurysmal Bone Cyst (ABC) focus.
Pathological examination supports this diagnosis and accounts for the recent accelerated growth of the lesion, as well as the onset of the patient’s symptoms.
1. Treatment Strategy:
- If the lesion causes persistent pain, significant deformity, or functional limitation, surgical resection or curettage may be performed. Bone grafting may be necessary if warranted.
- For asymptomatic or mildly symptomatic typical fibrous dysplasia, regular follow-up is advised to monitor further expansion or risk of pathological fracture.
- In cases with an aneurysmal bone cyst component and pronounced symptoms, surgical intervention remains the primary option.
2. Rehabilitation/Exercise Prescription (FITT-VP Principle):
- Frequency: Recommend rehabilitation exercises 3–4 times a week, progressing gradually under medical guidance post-surgery.
- Intensity: Begin with low to moderate intensity to avoid excessive stress on the affected rib. If surgery has been performed, increase intensity as bone healing allows.
- Time: Each session should last approximately 20–30 minutes; it may be divided into intervals and adjusted based on pain or subjective discomfort.
- Type: Focus on flexibility and low-impact exercises, such as gentle breathing exercises, shoulder girdle and chest wall muscle training, swimming, or light aerobic activities. Avoid high-impact sports that could directly stress the chest wall (e.g., high-intensity ball games).
- Progression: As recovery progresses and bone healing improves, gradually increase exercise intensity and include resistance training (e.g., using resistance bands or light weights) while continually monitoring pain and joint mobility.
- Precautions: If postoperative bone fragility remains or structural repair is incomplete, exercises should be supervised by a physician or rehabilitation specialist. If significant pain or discomfort arises, discontinue activity and seek medical advice.
This report is based on existing clinical and imaging information and is intended for reference only. It does not replace in-person consultations or professional medical advice. If the patient experiences any concerns or worsening symptoms, it is recommended to seek prompt medical attention for an individualized treatment plan.
Rib fibrous dysplasia associated with aneurysmal bone cyst
