Pathology II Notes
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Musculoskeletal System Overview
- Essential for movement, posture, and physical function.
- Skeletal Muscles: Key for voluntary motion, force generation, and metabolic regulation.
- Bones: Support, protection, movement, mineral storage, blood cell production, and energy storage.
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Soft Tissues and Joints
- Soft Tissues: Provide structural support, flexibility, and metabolic functions.
- Joints: Important for mobility, stability, shock absorption, and weight distribution.
- Susceptible to diseases that impact mobility and quality of life.
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Overview of Disease Exploration
- Focus on skeletal muscle diseases, bone diseases, and soft tissue tumors:
- Types, etiology, pathophysiology, clinical manifestations, investigations, complications, and prognosis.
- Early diagnosis and management crucial.
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Skeletal Muscle Diseases (Myopathies)
- Result from genetic, metabolic, inflammatory, infectious, or toxic factors.
- Classification:
A. Hereditary Myopathies
B. Inflammatory Myopathies
C. Toxic Myopathies
D. Metabolic Myopathies
E. Endocrine Myopathies
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A. Hereditary Myopathies
- Genetic mutations leading to muscle weakness.
- Includes various forms: Muscular Dystrophies, Channelopathies, etc.
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Muscular Dystrophies Overview
- Genetically inherited disorders with progressive muscle weakness.
- Key forms: DMD, BMD, Myotonic Dystrophy, etc.
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Duchenne Muscular Dystrophy (DMD)
- Severe X-linked recessive disorder causing muscle degeneration due to dystrophin absence.
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Pathogenesis of DMD
- Loss of dystrophin leads to muscle fiber damage and necrosis.
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DMD Clinical Manifestations
- Delayed walking, Gower’s sign, cardiomyopathy.
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DMD Complications and Prognosis
- Cardiomyopathy, respiratory failure.
- Typically fatal by early 20s.
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Becker Muscular Dystrophy (BMD)
- Milder variant of DMD with some dystrophin function retained.
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Myotonic Dystrophy
- Autosomal dominant disorder; characterized by progressive weakness and myotonia.
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Facioscapulohumeral Dystrophy
- Autodominant affecting facial and shoulder muscles.
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Oculopharyngeal Muscular Dystrophy
- Progressive weakness in eyelid and throat muscles, leading to ptosis and dysphagia.
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Congenital Myasthenia
- Genetic neuromuscular disorder causing muscle weakness due to impaired transmission.
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B. Inflammatory Myopathies
- Autoimmune conditions with muscle inflammation.
- Includes Polymyositis & Dermatomyositis.
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Infective Myositis
- Muscle inflammation due to infections (bacterial, viral, fungal).
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C. Toxic Myopathies
- Muscle disorders from toxic exposures.
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- Disorders with impaired energy production due to enzymatic defects.
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E. Endocrine Myopathies
- Disorders affecting neuromuscular transmission such as Myasthenia Gravis.
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Diseases of Bone: Osteoporosis
- Characterized by decreased bone mass and increased fragility.
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Von Recklinghausen Disease
- Severe hyperparathyroidism causing cystic bone changes.
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Osteomalacia and Rickets
- Defective mineralization due to vitamin D deficiency.
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Paget Disease
- Disorganized remodeling leading to structurally weak bone.
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Non-neoplastic Bone Diseases
1. Scurvy
- Vitamin C deficiency affecting collagen synthesis.
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2. Achondroplasia
- Genetic cartilage disorder leading to dwarfism.
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4. Osteogenesis Imperfecta
- Genetic disorder resulting in fragile bones due to collagen defects.
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5. Pyogenic Osteomyelitis
- Bacterial bone infection typically caused by Staphylococcus aureus.
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6. Tuberculous Osteomyelitis
- Bone infection by Mycobacterium tuberculosis, often affecting the spine.
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Benign Bone Tumors: Osteochondroma
- Common benign tumor at growth plate.
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Malignant Bone Tumors: Osteosarcoma
- Most common primary malignant bone tumor; responds well to treatment.
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Ewing Sarcoma
- Highly aggressive malignant tumor of bone.
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Chondrosarcoma
- Malignant tumor from cartilage-producing cells; prognosis depends on grade.