The patient, an 80-year-old woman, presented to the emergency department for respiratory distress. A chest X-ray and a CT were performed. The patient had clinical history of osteoarthritis.
The chest X-ray (Fig. 1) showed an undulating irregular hyperostotic cortical pattern along the long axis of multiple left ribs and the first right rib, resembling melting wax dripping down the side of a candle - the "dripping candle wax sign". Also note the heterogeneous amorphous calcifications around the shoulder joint and scapula.
Axial CT images of the chest revealed undulating irregular sclerotic changes affecting mostly the left ribs (Fig. 2a-f) but also the first right rib (Fig. 2a), a spinous process (Fig. 2c), the left scapula (Fig. 2a-c) and a costovertebral joint (Fig. 2g).
Melorheostosis (also known as Leri disease) is a rare sclerosing bone dysplasia [1]. Men and women are equally affected and the prevalence of the disease is 0.9 per million. The age of presentation ranges from 2 to 64 years, with approximately half the cases being diagnosed before 20 years of age [2].
Clinical manifestations of melorheostosis are variable, ranging from chronic pain, joint stiffness, deformity, contractures and muscle wasting. Patients may be asymptomatic and the disease can present as an incidental finding on imaging [3].
There are several radiological patterns described, including osteoma-like, candle-wax appearance (the classic pattern), osteopathia striata-like, soft tissue calcifications and a mixed pattern.
The dripping candle wax appearance consists of irregular thickening of cortical bone, with thick undulating ridges of bone, reminiscent of molten wax [4]. This sign was described initially on conventional radiographs, although the findings are similar on computed tomography (CT) [3 - 5].
The differential diagnosis includes osteophatia striata, osteopoikilosis, osteosarcoma and myositis ossificans. There are some imaging findings that may allow differentiation from melorheostosis, although the correct diagnosis is not always easy due to imaging features overlap and the existence of overlap syndromes, in which features of two or more sclerosing dysplasias are combined, a combination of melorheostosis, osteopoikilosis and osteopathia striata being the most frequent. The presence of longitudinal dense striations in osteopathia striata, punctate, rounded bone islands surrounding joints in osteopoikilosis, bone destruction in osteosarcoma, and soft tissue ossification in myositis ossificans may help differentiate from melorheostosis, although some of them are present in melorheostosis as well [6].
Most cases are benign and do not require operative intervention, with only conservative measures such as manipulation, analgesia, physical therapy, bisphosphonates and casting being used. More invasive therapies for severely symptomatic cases consist of surgical soft-tissue procedures and even, in very severe cases, amputation [7].
Polyostotic melorheostosis
1. On the patient’s chest X-ray and chest CT images, localized bony thickening is observed, showing an irregular sclerotic appearance primarily involving the upper thoracic skeletal structures.
2. CT images reveal the typical “dripping wax” sign, characterized by irregular, undulating proliferative sclerosis on the outer cortex of the bone, with increased density of the trabeculae.
3. The overall lesion margin is relatively well-defined, with no significant soft tissue swelling or marked bone destruction in the surrounding area.
4. No acute fractures or soft tissue injuries caused by trauma are observed. There are no obvious new shadows in the lung fields, but clinical symptoms relating to the respiratory system should be monitored accordingly.
Based on the patient’s advanced age (80 years old) and the findings of sclerotic bone lesions on imaging, potential diagnoses/differential diagnoses include:
1. Melorheostosis (Leri disease): A rare sclerosing bone developmental disorder. A common feature is the “wax-drop” / “dripping wax” pattern of bone thickening. Patients may present with local pain, limited joint mobility, or may be asymptomatic.
2. Osteopathia striata: Characterized by linear bony sclerosis, usually presented as vertical striations. While part of the differential, these linear patterns differ from “dripping wax” morphology.
3. Osteopoikilosis: Multiple focal sclerotic areas, often round or ovoid “bone islands” scattered throughout the skeleton, typically uniform in shape.
4. Osteosarcoma: A malignant bone tumor that can show either sclerotic or destructive features, usually with periosteal reaction and soft tissue mass, and an ill-defined lesion boundary.
5. Myositis ossificans: More often characterized by heterotopic ossification within soft tissue. Early stages can resemble a sclerotic lesion, but usually there is a history of trauma or signs of inflammation in the adjacent soft tissue.
Considering the patient’s advanced age, history of bone and joint issues, and the imaging findings of a characteristic “dripping wax” sclerosis with relatively well-demarcated margins and no obvious soft tissue swelling, the most likely diagnosis is Melorheostosis (Leri disease).
If further confirmation is needed, bone scan or molecular assessments may be considered. However, based on the current imaging and clinical history, the likelihood of Melorheostosis is high.
1. Conservative Treatment:
- Most cases of Melorheostosis progress slowly and remain largely benign, allowing for conservative management.
- Use appropriate analgesics (e.g., NSAIDs) when necessary to alleviate any potential pain caused by the lesion.
- Physical therapy (physical agent therapy, joint mobilization) and gentle stretching to prevent or reduce joint contractures.
- Avoid excessive weight-bearing or high-impact activities that could risk fractures, especially when the sclerotic bone region may not be sufficiently robust.
2. Surgical Intervention:
- In very rare instances where severe pain, deformity, or significant functional limitations occur, soft tissue release or surgical resection of affected bone may be considered.
- In extreme cases of severe involvement with lost function, amputation might be indicated, though this is extraordinarily rare.
3. Rehabilitation & Exercise Prescription (FITT-VP Principle):
- Frequency: Depending on the patient’s cardiopulmonary status and joint condition, engage in low-intensity exercise 2-3 times per week (e.g., gentle stretching, mild joint mobilization).
- Intensity: Begin with light to moderate intensity; start with simple range-of-motion exercises or seated low-resistance upper/lower limb workouts. Avoid high-impact activities.
- Time: 15-30 minutes per session, gradually increasing as tolerated. If respiratory issues exist, monitor oxygen saturation, heart rate, and breathing status during exercise.
- Type: Choose safer forms of exercise such as seated cycling, slow walking, or aquatic exercise (if cardiopulmonary function allows and no other contraindications exist).
- Progression: Once the current intensity is tolerated, extend the exercise duration or slightly increase resistance. Avoid abrupt increases; reevaluate bone and joint status with professional guidance every few weeks before adjusting.
- Volume: Gradually increase total exercise volume according to individual tolerance; maintain a focus on improving joint flexibility and muscle strength.
- Maintain balance and use assistive devices (e.g., walkers, canes) if needed to ensure safety.
- For those with reduced cardiopulmonary function, incorporate breathing exercises (e.g., diaphragmatic breathing, pursed-lip breathing) under medical or rehabilitative supervision. Closely monitor subjective symptoms and vital signs during activity.
Disclaimer: This report is based on the patient’s basic information and imaging data for academic and clinical reference purposes. It does not replace an in-person consultation or professional medical advice. In case of any discomfort or concerns, please seek medical attention promptly and undergo further check-ups and personalized treatment recommendations.
Polyostotic melorheostosis
