Pediatric Musculoskeletal, Immunologic/Autoimmune, & Rheumatologic Disorders: Structured Study Guide

Pediatric Musculoskeletal, Immunologic/Autoimmune, & Rheumatologic Disorders

Overview

This study guide summarizes key pediatric acute care topics related to musculoskeletal, immunologic/autoimmune, and rheumatologic disorders. Each topic is organized by pathophysiology, epidemiology/etiology, clinical presentation, differential diagnosis, plan of care, diagnosis/discharge, and clinical pearls.

Musculoskeletal Disorders

Pediatric Acute Compartment Syndrome

• Pathophysiology: Increased pressure within a muscle compartment leads to decreased blood flow and tissue ischemia.

• Etiology: Trauma, fractures, burns, vascular injuries.

• Presentation: Pain out of proportion, pallor, paresthesia, paralysis, pulselessness (the "5 P's").

• Differential Diagnosis: Cellulitis, deep vein thrombosis, neuropathy.

• Plan of Care: Observation for symptoms, emergent fasciotomy if compartment syndrome is suspected.

• Diagnosis & Discharge: Clinical diagnosis, monitor for neurovascular compromise.

• Pearls: Early recognition is critical to prevent permanent damage.

Hip Dysplasia

• Pathophysiology: Abnormal development of the hip joint, leading to instability or dislocation.

• Etiology: Family history, oligohydramnios, breech presentation.

• Presentation: Asymmetric thigh/gluteal folds, limited abduction, positive Ortolani/Barlow tests.

• Differential Diagnosis: Neuromuscular disorders, trauma.

• Plan of Care: Pavlik harness for infants, open reduction and pelvic osteotomy for older children.

• Diagnosis & Discharge: Imaging (ultrasound, X-ray), monitor for hip development.

• Pearls: Early intervention improves outcomes.

Diskitis

• Pathophysiology: Inflammation/infection of the intervertebral disc, often bacterial.

• Etiology: Most common in children under 5, often hematogenous spread.

• Presentation: Refusal to walk, back pain, fever, lumbar lordosis, fatigue.

• Differential Diagnosis: Spinal tumor, trauma.

• Plan of Care: Laboratory and imaging (ESR, CRP, MRI), antibiotics.

• Diagnosis & Discharge: Long-term antibiotics, monitor for resolution.

• Pearls: Duration of treatment is based on laboratory values.

Legg-Calvé-Perthes Disease

• Pathophysiology: Idiopathic avascular necrosis of the femoral head.

• Etiology: Most common in boys aged 4-8 years.

• Presentation: Persistent pain, limp, limited hip motion.

• Differential Diagnosis: Septic hip, trauma.

• Plan of Care: Activity restriction, physical therapy, possible surgery.

• Diagnosis & Discharge: Imaging (X-ray, MRI), monitor for femoral head healing.

• Pearls: Early diagnosis and management improve outcomes.

Slipped Capital Femoral Epiphysis (SCFE)

• Pathophysiology: Displacement of the femoral head at the growth plate.

• Etiology: Obesity, rapid growth, endocrine disorders.

• Presentation: Hip/knee pain, limp, limited internal rotation.

• Differential Diagnosis: Trauma, cyst, tumor.

• Plan of Care: Non-weight bearing, surgical fixation.

• Diagnosis & Discharge: Imaging, monitor for avascular necrosis.

• Pearls: Early intervention prevents complications.

Toxic Synovitis

• Pathophysiology: Transient inflammation of the synovium, usually post-viral.

• Etiology: Ages 3-10, often follows upper respiratory infection.

• Presentation: Hip pain, limp, afebrile or low-grade fever.

• Differential Diagnosis: Septic arthritis, trauma.

• Plan of Care: Supportive care, NSAIDs.

• Diagnosis & Discharge: Diagnosis of exclusion, monitor for improvement.

• Pearls: Symptoms resolve within 1-2 weeks.

Osteomyelitis

• Pathophysiology: Infection of the bone, often bacterial.

• Etiology: Hematogenous spread, trauma, surgery.

• Presentation: Fever, localized pain, swelling, decreased movement.

• Differential Diagnosis: Fracture, tumor, septic arthritis.

• Plan of Care: IV antibiotics, possible surgical drainage.

• Diagnosis & Discharge: Imaging (MRI, bone scan), monitor for resolution.

• Pearls: Early treatment prevents chronic complications.

Rhabdomyolysis

• Pathophysiology: Muscle breakdown releases myoglobin, leading to renal injury.

• Etiology: Trauma, infection, metabolic/genetic disorders.

• Presentation: Muscle pain, weakness, dark urine.

• Differential Diagnosis: Muscular dystrophy, Guillain-Barré syndrome.

• Plan of Care: IV fluids, monitor renal function, correct electrolyte imbalances.

• Diagnosis & Discharge: CK > 1,000 U/L, monitor for renal failure.

• Pearls: Check CK levels and renal function regularly.

Immunologic/Autoimmune Disorders

Primary Immunodeficiencies

• Pathophysiology: Genetic defects in immune system components (e.g., B cells, T cells).

• Etiology: Family history, consanguinity, recurrent infections.

• Presentation: Recurrent, severe, or unusual infections; poor response to vaccines.

• Differential Diagnosis: Chronic infections, malignancy.

• Plan of Care: Immunoglobulin replacement, prophylactic antibiotics, advanced testing.

• Diagnosis & Discharge: Monitor for infection, educate family.

• Pearls: Early diagnosis improves prognosis.

Secondary Immunodeficiencies

• Pathophysiology: Acquired defects due to HIV, malnutrition, chemotherapy.

• Etiology: Poor nutrition, chronic disease, medications.

• Presentation: Recurrent infections, poor growth.

• Differential Diagnosis: Primary immunodeficiency, chronic illness.

• Plan of Care: Treat underlying cause, optimize nutrition.

• Diagnosis & Discharge: Monitor for infection, adherence to therapy.

• Pearls: Adherence to therapy is critical.

Juvenile Idiopathic Arthritis (JIA)

• Pathophysiology: Chronic autoimmune inflammation of joints.

• Etiology: Genetic predisposition, environmental triggers.

• Presentation: Joint pain, swelling, morning stiffness, limited range of motion.

• Differential Diagnosis: Malignancy, mechanical trauma.

• Plan of Care: NSAIDs, DMARDs, physical therapy.

• Diagnosis & Discharge: Imaging, laboratory tests (ESR, CRP), monitor for growth and development.

• Pearls: Early aggressive therapy improves outcomes.

Systemic Lupus Erythematosus (SLE)

• Pathophysiology: Autoimmune disease affecting multiple organ systems.

• Etiology: Genetic predisposition, environmental triggers.

• Presentation: Malar rash, arthritis, renal involvement, serositis.

• Differential Diagnosis: Infection, other autoimmune diseases.

• Plan of Care: Immunosuppressive therapy, corticosteroids, hydroxychloroquine.

• Diagnosis & Discharge: Laboratory studies (ANA, anti-dsDNA), monitor for organ involvement.

• Pearls: Multidisciplinary care is essential.

Vasculitis

• Definition: Inflammation of blood vessels, can affect any organ system.

• Etiology: Autoimmune, infection, drug reaction.

• Presentation: Rash, fever, organ dysfunction.

• Differential Diagnosis: Sepsis, other autoimmune diseases.

• Plan of Care: Immunosuppressive therapy, supportive care.

• Diagnosis & Discharge: Comprehensive team approach, monitor for relapse.

• Pearls: Early diagnosis and treatment improve prognosis.

Allergic and Autoimmune Conditions

Allergic Rhinitis

• Pathophysiology: IgE-mediated inflammation of nasal mucosa.

• Etiology: Environmental allergens, family history.

• Presentation: Sneezing, rhinorrhea, nasal congestion, itchy eyes.

• Differential Diagnosis: Vasomotor rhinitis, sinusitis.

• Plan of Care: Avoid triggers, antihistamines, nasal steroids.

• Diagnosis & Discharge: Clinical diagnosis, monitor for symptom control.

• Pearls: Combination therapy may be needed.

Food Allergy

• Pathophysiology: IgE-mediated immune response to food proteins.

• Etiology: Genetic predisposition, early exposure.

• Presentation: Anaphylaxis, urticaria, GI symptoms.

• Differential Diagnosis: Lactose intolerance, celiac disease.

• Plan of Care: Avoidance of trigger foods, emergency epinephrine.

• Diagnosis & Discharge: Allergy testing, education on avoidance.

• Pearls: Hx and recognition of symptoms are key to diagnosis.

Comparative Table: Key Pediatric Musculoskeletal and Immunologic Disorders

Disorder	Pathophysiology	Presentation	Diagnosis	Management
Compartment Syndrome	Increased pressure in muscle compartment	Pain, pallor, paresthesia, paralysis, pulselessness	Clinical, neurovascular assessment	Emergent fasciotomy
Hip Dysplasia	Abnormal hip joint development	Asymmetric folds, limited abduction	Imaging, Ortolani/Barlow tests	Pavlik harness, surgery
JIA	Autoimmune joint inflammation	Joint pain, swelling, stiffness	Imaging, labs (ESR, CRP)	NSAIDs, DMARDs
SLE	Autoimmune, multi-organ	Malar rash, arthritis, renal	ANA, anti-dsDNA	Immunosuppressives
Osteomyelitis	Bacterial bone infection	Pain, fever, swelling	MRI, bone scan	IV antibiotics, surgery

Additional info:

• Topics such as pathophysiology, clinical presentation, and management are expanded for clarity and academic completeness.

• Comparisons between similar diagnoses (e.g., JIA vs. SLE, primary vs. secondary immunodeficiencies) are important for clinical reasoning.

• Early recognition and intervention are emphasized throughout for optimal patient outcomes.