Skeletal System Pathology Flashcards
MC bone type for osteomyelitis in children
Long bones
MC bones type for osteomyelitis in adults
Vertebrae, pelvis
MC organism isolated from osteomyelitis
Staph aureus
MC route of infx for osteomyelitis in children
Hematogenous
MC organism isolated from osteomyelitis in infants
Group B Strep
MC etiology of osteomyelitis in adults
Injury exposing bone to local infx
MC location for solitary bone cyst
Distal ends of long bones
MC population for solitary bone cyst
Boys
MC location for aneurysmal bone cyst
Metaphysis of longs bones
MC population for aneurysmal bone cyst
Young women
MC location for osteosarcoma
Distal femur/knee
MC joint disease
Osteoarthritis
MC cause of secondary OA
DM
Nail signs in psoriasis
Pitting
Onycholysis
MC & 2MC bug in septic arthritis in adults
Staph, Strep
MC type of muscular dystrophy
Duchenne’s
MC muscle groups affected in Duchenne’s MD
Large, proximal groups
MC presentation of rhabdomyoma
Round mass in the neck
MC soft tissue tumor in kids and location
Rhabdomyosarcoma
Orbit, face, scalp, neck
Which bug is each of these populations susceptible to in developing septic arthritis?
Sickle cell patients
Young adults
Elderly and IV drug users
Sickle cell – Salmonella
Young adults – Neisseria gonorrhea
Elderly, IV drug users – E. coli
Osteogenesis imperfecta
- Pathology
- Cause
Brittle bones
Type 1 collagen deficiency
Rickets
- Pathology
- Cause
- Population
- Bone softening
- Vit D deficiency dt severe malnutrition
- Children
Paget’s disease of bone
- Pathology
- Population
- Increased osteoblast & osteoclast activity –> increased calcification of bone
- Develops in 4th decade, Caucasian, M>F
Osteopetrosis
- Pathology
- Etiology
- Population
- Bones harden and become more dense (still brittle though)
- Genetic
- Bimodal: early childhood, adults
Osteoid osteoma
- Description
- Population
- Small area of neoplastic tissue surrounded by mature bone
- Children, young adults
Multiple myeloma–definition
Malignancy in one clone of plasma cells
Rheumatoid arthritis
- Description
- Etiology
- Population
- Progressive deforming polyarthritis with chronic systemic inflammatory dz
- Unknown
- Middle age, F>M
Rheumatoid arthritis
- Description
- Etiology
- Population
- Progressive deforming polyarthritis with chronic systemic inflammatory dz
- Unknown
- Middle age, F>M
Ankylosing spondylitis
- Definition
- HLA
- Population
- Chronic inflammatory dz of axial skeleton, especially SI joints
- HLA-B27
- M>F, onset in adolescence
Reactive arthritis
- Definition
- Population
- Autoimmune reaction following GI/GU infx
- Males in 20s and 30s
Gout
- Definition
- Etiology
- Presentation
- Pathognomonic finding
- Deposition of urate crystals in joint dt hyperuricemia
- Overproduction and/or underexcretion of uric acid
- Exquisitely painful distal monoarthritis (esp 1st MTP)
- Tophus
Pseudogout
- Definition
- Population
- Deposition of calcium pyrophosphate crystals in joints
- Older adults
Ganglion cyst vs Synovial cyst
Ganglion: no communication with joint space
Synovial: herniation of synovial fluid through joint capsule
Duchenne’s MD
- Protein
- Pathology
- Inheritance
- Course
- Dystrophin
- Absence of dystrophin –> excess Ca –> oxidative stress –> necrosis of muscle
- Sex linked
- Onset age 2-5, death by 20s
Myasthenia Gravis
- Pathology
- Linked to abnormalities in what organ?
- Populations
- Antagonistic antibodies to acetylcholine receptor, causes fluctuating weakness
- Thymus
- Women under 40, both sexes 50-70
Lambert-Eaton
- Description
- Strong association with…?
- Pathology
- Changes in weakness with exertion
- Progressive proximal muscle weakness
- Small cell lung cancer
- Antibodies to presynaptic Ca channel –> impaired acetylcholine release
- Greater strength with initial exertion/mild exercise, but weakness with prolonged exertion
What are the three most common idiopathic inflammatory myopathies?
Dermatomyositis, polymyositis, and inclusion body myositis
Dermatomyositis
- Systems affected
- Possible etiologies
- Mechanism
- Population
- Skeletal muscle and skin
- Post-viral, often paraneoplastic
- Complement-mediated damage to blood vessels
- Primarily adults, also children 5-14
Classic microscopic finding of dermatomyositis
Mixed B and T cell perivascular infiltrate with perifascicular muscle fiber atrophy
Clinical manifestations of dermatomyositis
- Periorbital heliotrope rash (summetric, purple-red maculopapular rash on eyelids)
- Gottron’s sign (red maculopapular rash over dorsal MCPs and IPs)
Polymyositis
- Presentation
- Population
- Mechanism
- Bilateral proximal muscle weakness including neck flexors; never ocular muscles
- Almost exclusively adults
- WBC infiltrate of muscle fibers
Histo findings of polymyositis
Muscle fibers pale and enlarged, with lymphocyte/macrophage infiltrate
Inclusion body myositis
- Clinical description
- Histo (muscle bx)
- Slowly progressive weakness and wasting of distal and proximal muscles, esp arms and legs
- Focal areas of WBCs, vacuoles, amyloid deposits, and inclusion bodies
Rhabdomyoma
Description and presentation
Benign striated muscle tumor
Round mass in region of the neck
MC soft tissue tumor in children and MC sites
Rhabdomyosarcoma
Within the orbit or face/scalp/neck/extremities
What cell line does rhabdomyosarcoma arise from?
What are histo findings?
Embryonal mesenchymal cells
Pleiomorphic cells w/ high variability; interweaving bundles of spindle-shaped cells
X-ray findings of osteoarthritis (4)
Joint-space narrowing
Osteophytes
Subchondral bone cysts
Greater density
Heberden’s nodes are at the _____
Bouchard’s nodes are at the ______
Heberden’s – DIPs
Bouchard’s – PIPs
Histo of osteomyelitis
Lytic center with ring of sclerosis
Eye finding in osteogenesis imperfecta
Robin’s egg eyes: sclera turn blue
With rickets, you see genu ____ in toddlers but genu ____ in older children.
Varum toddlers
Valgum older children
Finding on the chest in rickets
Rachitic rosary: prominent knobs of bone at the costochondral joints
Pathognomonic histo finding for Paget’s disease
Mosaic pattern of lamellar bone
Lab finding for Paget’s disease
Markedly elevated serum alk phos
X ray finding of Paget’s disease
Cotton ball skull with thickening of calvarium
X ray finding of solitary bone cyst
Smooth, thin cortex
Close to epiphysis
Symmetrical
X ray finding of aneurysmal bone cyst
Distortion of bone, less symmetry
Honeycomb appearance
X ray finding of an osteoid osteoma
Small, round, well-circumscribed lesion near the cortex
Characteristic finding of osteosarcoma
Skip lesions
Histo finding of fibrosarcoma
Sheets of spindle-shaped cells
X ray finding of giant cell tumor
Expanded bone contours with non-sclerotic borders
Histo and X ray findings of Ewing sarcoma
Uniform, densely packed cells
Moth-eaten bone
X ray finding of multiple myeloma
Clinical features
Lytic bone lesions
Bone pain, fractures
X ray finding of mets to bone
Ivory vertebra sign
Labs for RA
RF (anti-IgG) – more sensitive
anti-CCP – highly specific
HLA-DR4
Gene assoc w/ ankylosing spondylitis
HLA-B27
Classic clinical picture of reactive arthritis
Conjunctivitis, non-gonococcal urethritis, arthritis
Derm manifestation of lyme disease
Erythema chronicum migrans
Pathognomonic lesion of gout
Topus
Histo finding of myasthenia gravis
Lymphocytic accumulation in muscle, pale and atrophic muscle fibers
Gross finding of osteoid osteoma
Gritty, cherry red lesion