What could cause severe musculoskeletal (musculoskeletal system) asymmetry, particularly in the hips, torso, and ribcage, in a patient without a history of sports or dancing, and with an unknown age, gender, and medical history?

Severe Musculoskeletal Asymmetry Without Sports/Dance History

The most likely causes of severe musculoskeletal asymmetry affecting the hips, torso, and ribcage in a patient without sports or dance history are idiopathic scoliosis (which accounts for 75-80% of childhood scoliosis), congenital vertebral anomalies, connective tissue disorders (particularly Marfan syndrome and related conditions), and neuromuscular conditions. 1

Primary Structural Causes

Scoliosis (Most Common)

• Idiopathic scoliosis is the leading cause of spinal asymmetry, representing at least 75-80% of cases, with adolescent-onset (ages 10-18) comprising about 90% of idiopathic cases 1
• Scoliosis commonly presents with asymmetric waistline, trunk shift, and rib cage deformity 2
• Prevalence in the pediatric population is approximately 2%, making this the most statistically likely diagnosis 1
• Routine screening should include physical examination with scoliometer, and radiography when clinically indicated 1

Congenital Vertebral Anomalies

• Anomalies of vertebral formation or segmentation account for up to 10% of surgical scoliosis patients 1
• These patients have more than 20% incidence of neural axis abnormalities including hydrosyringomyelia, Chiari malformation, and cord tethering 1
• MRI evaluation is necessary to rule out intraspinal abnormalities, especially in atypical presentations 2

Connective Tissue Disorders

Marfan Syndrome and Related Conditions

• Marfan syndrome presents with marfanoid habitus, skeletal asymmetry including scoliosis, pectus deformities, and joint hypermobility 1
• Congenital contractural arachnodactyly (CCA) presents with marfanoid habitus, flexion contractures of multiple joints including elbows, hips, and knees, plus kyphoscoliosis 1
• Annual physical examination for scoliosis is recommended until adult height is reached in patients with suspected connective tissue disorders 1
• Echocardiography should be performed every 2 years until adult height is reached to monitor for aortic root dilation 1

Other Genetic Syndromes

• 22q11.2 deletion syndrome commonly presents with scoliosis (usually adolescent idiopathic type) that may require bracing or surgical intervention 1
• Routine scoliosis screening is recommended in 22q11.2DS, with some centers performing radiography at 2-year intervals from age 6 until skeletal maturity 1

Neuromuscular and Neurological Causes

Spinal Cord Abnormalities

• Up to 2-4% of adolescent idiopathic scoliosis patients have neural axis abnormalities including Chiari I malformation, cord syrinx, cord tethering, or intrinsic spinal cord tumor 1
• Tethered cord syndrome can present with leg pain and gait abnormalities that may contribute to compensatory postural changes 3, 4
• Red flags requiring MRI include: left thoracic curve, short segment curve, absence of apical segment lordosis/kyphosis, rapid curve progression (>1° per month), functionally disruptive pain, focal neurologic findings, and male sex 1

Inflammatory Myopathies

• Dermatomyositis presents with symmetric proximal muscle weakness developing over weeks to months, though asymmetric involvement can occur 1
• Muscle weakness can lead to compensatory postural changes and secondary skeletal asymmetry 1

Diagnostic Approach

Initial Evaluation

• Posteroanterior (PA) standing radiography is the primary imaging modality for diagnosing and classifying scoliosis 1
• Physical examination should assess for cutaneous stigmata (hemangioma, hairy patches, nevi) suggesting spinal dysraphism 1
• Evaluate for marfanoid features: arm span-to-height ratio, thumb and wrist signs, pectus deformities, joint hypermobility 1

Advanced Imaging Indications

• MRI is indicated when risk factors for neural axis abnormalities are present, particularly absence of apical segment lordosis/kyphosis (the most consistent risk factor) 1
• One-time cervical spine screening with radiography including atlas-dens measurements in flexion and extension is recommended around age 4 years in patients with genetic syndromes 1
• CT or magnetic resonance angiography of thorax and abdomen should be considered if familial arterial tortuosity syndrome is suspected 1

Laboratory Evaluation

• Muscle enzyme levels (creatine kinase) if inflammatory myopathy is suspected 1
• Genetic testing for FBN1 mutations if Marfan syndrome features are present 1
• Myositis-specific autoantibodies may define subgroups and suggest extramuscular organ involvement 1

Critical Pitfalls to Avoid

• Do not assume idiopathic scoliosis without excluding congenital vertebral anomalies, which require different management and have higher rates of neural axis abnormalities 1
• Avoid missing connective tissue disorders by failing to examine for systemic features beyond the musculoskeletal system, particularly cardiovascular involvement 1
• Do not overlook the possibility of underlying neuromuscular disease, as conditions like cerebral palsy and muscular dystrophy commonly present with scoliosis 1
• Failure to obtain MRI when red flags are present may miss treatable intraspinal pathology 1
• Severe curves (>50 degrees) may continue to progress at approximately 1 degree per year even after skeletal maturity, requiring ongoing monitoring 2