Pathology Flashcards
What auto-antibodies are associated with RA and each of the connective tissue diseases?
Rheumatoid arthritis – Anti-CCP
Lupus – Anti-dsDNA
Sclerosis - Limited - Anti centromere
- Diffuse - Anti-Scl-70
Dermatomyositis – Anti Jo
Sjogrens – Anti Ro LaDescribe the difference in pathology of rheumatoid arthritis
Acute phases:
- Pannus formation – inflammatory granulation tissue
- Hyperplastic / reactive synovium
Chronic phase:
- Fibrosis
- deformity
Give examples of three metabolic conditions which have MSK consequences
Pagets
Osteomalacia
Crystal arthropathies
What processes allow the formation of uric acid crystals?
Uric acid is the end-product of purine synthesis
Adenine (A) and guanine (G) are purine based
=> urate is formed in DNA replication
What are the two main reasons for which hyperuricaemia would occur?
Increased production
Or
Reduced excretion
For what reasons would the body produce more uric acid than normal?
Idiopathic - unknown enzyme defect (90%)
Known enzyme defect - HGPRT deficiency
(Lysch Nyhan syndrome)
Increased cell turnover
- Psoriasis
- Cancer
What can be responsible for under excretion of uric acid?
Drug side effect
=> thiazide diuretics reduce urate excretion
In what joints do the uric acid crystals usually deposit?
joints at lower temperatures than core body temperature
What secondary degenerative changes can gout cause?
Deposition in soft tissues – gouty tophus
Renal disease – stones and direct deposition in tubules and interstitium
What features would be seen on histology of a sample with gout?
Amorphous eosinophilic debris and inflammation
(giant cells)
Crystals LOST during tissue processing
In what individuals does pseudogout usually present?
Usually older individuals in their large joints
What can cause pseudogout?
Usually idiopathic
known causes: hypercalcaemia (inc. hyperparathyroidism), haemachromatosis hypomagnesaemia ochronsis hypothyroidism
What shape do pseudogout crystals appear on microscopy?
Rhomboid shaped crystals
Thicker and bigger than needle shaped urate crystals
What is Paget’s disease of bone?
Abnormality of bone turn-over
=> Increased osteoclastic activity
more bone but not normally structured
What can predispose to Paget’s disease?
Genetic factors
Viruses:
- paramyxovirus
- measles
- Resp. Syncytial Virus
What are the three stages in Paget’s disease?
Osteolytic
mixed
burnt out
What is the end result in Paget’s disease?
thick excess bone
abnormal reversal lines – mosaic pattern
What bones does Paget’s disease affect?
Can affect ALL bones usually axial, small bones less commonly affected
What can cause pain in Paget’s disease?
microfracture or nerve compression
What secondary problems can Paget’s disease cause?
Increased metabolism
=> heat, warm skin,
AV shunt effectively high output heart failure
Secondary malignancy – osteosarcoma
What is osteomalacia?
Abnormal vitamin D metabolism
Sun exposure related
Causes:
- Rickets in young pts
- Bowed legs, square heads, pigeon chest, rickety rosary
Describe the simple pathogenesis of a fracture
Trauma
Bone breaks – pain from periosteum
Haemorrhage
Remember – rubor, calor, tumour and dolor
At what stage after a bone is fractured, does the callus reach its maximum girth
2-3 weeks
What can cause a pathological fracture
Osteoporosis is very common
Tumours
Benign - usually children and primary
Malignant – adults and metastatic
What cancers commonly metastasize to bone?
Breast Bronchus Lung Prostate Thyroid Renal
What conditions can cause bony lesions?
myeloma/plasmacytoma
Malignant proliferation of plasma cells. Causes bony lesions
What is avascular necrosis?
Bone infarction
What can cause avascular necrosis?
trauma (scaphoid) alcohol dysbarism Steroid injection sickle cell disease, infection
How do subchondral cysts form?
synovial fluid through bone forming small cysts
Why do osteophytes form in degenerative diseases such as osteoarthritis?
remodelling of bone to cope with stress
Remodelling = disorganised and produces abnormal outgrowths - osteophytes
Give examples of benign tumours of bone
Ganglion Cyst
Giant cell tumour
Fibromatosis
Fibrous dysplasia
Where does a ganglion cyst usually present?
peripheral lump
near a joint capsule or tendon sheath
Common around the wrist
Why is a ganglion cyst not a true cyst?
It has no epithelial lining
How do ganglion cysts appear histologically?
- space with myxoid material
- Secondary inflammatory changes
Give some examples of common superficial fibromatoses
Dupuytren’s
Knuckle pads
Plantar
Penile – Peyronie’s
How do deep fibromatoses differ from superficial fibromatoses?
- Mesenteric or pelvic
- Desmoid tumours
- Association with Gardner’s Syndrome
Where can giant cell tumours present?
Pigmented villonodular synovitis – present in large joints
Giant cell tumour of tendon sheath – present in small joints e.g. digits
Giant cell tumours in large joints are more easily excised than those in smaller joints. TRUE/FALSE?
FALSE
small nodules are easily excised (with occasional recurrence)
PVNS – more destructive and diffuse in a joint space. Difficult to excise and can often recur.
How do angiolipomas usually present?
multiple and peripheral
painful subcutaneous lesion
A leiomyoma is a tumour of what?
Smooth muscle
=> Can arise from large vessel walls (e.g. muscular veins)
What rare benign tumour can occur from skeletal muscle?
Rhabdomyomas
What is the name given to a benign tumour of cartilage?
Enchondroma
Where do simple osteomas usually present?
In the cranial bones
=> lumps often seen on forehead of patient
What name is given to the condition where a patient present with multiple osteomas?
Gardner’s syndrome
What age group are most commonly affected by Osteosarcoma?
paediatric age-group
occurs in Long bones
How is an osteosarcoma defined?
malignant tumour that produces osteoid is an osteosarcoma until proven otherwise
Who is most likely to be affected by Ewing’s sarcoma?
children and adolscents
Where do Ewing’s sarcomas commonly affect?
Any soft tissue or bony location
=> often long bones in adolescents
Ewing’s sarcomas are destructive, rapidly growing and highly malignant. TRUE/FALSE?
TRUE
What cells are thought to mutate and give rise to Ewing’s sarcomas?
primitive mesenchymal or neuroectodermal cell
How do Ewing’s sarcomas appear in clinic?
Small round blue cell tumours
What type of cancer do you always want to exclude?
Carcinoma group:
- Sarcomatoid carcinoma
- carcinosarcoma
- metaplastic carcinoma
What is a Pseudosarcoma?
Tissues undergoing repair often appear very atypical and the diagnosis can be very difficult
What reactive lesion appears histologically as a chaotic appearance with haemorrhage, pseudocystic spaces and large atypical cells?
Nodular Fasciitis
What is Myositis ossificans?
A reactive lesion which affects large muscles:
- quadriceps
- gluteus
- brachialis (occasionally)
Chondrosarcomas affect what parts of the body?
Axial skeleton (pelvis) Head and Neck
NOT common in peripheries
Where do rheumatoid nodules usually present, and what are they?
Elbow
Necrobiotic granulomatous inflammation
