Term 3 case studies

Question 1

A previously healthy 30 year old female, who has a history of frequent travel to remote areas of the developing world, presents with a history of respiratory complaints, mild fever and increased white blood cells. She now has back pain which is causing immobility.

You are requested to x ray her lungs and lumbar spine.

You suspect an infection by a mycobacterium which may have spread to the spine.

Describe the pathology of the spondylitis (disco-vertebral) this mycobacterium might cause

Answer 1

1. The basic pathological process is vascular seeding of bacillus into the vertebral bodies, particularly L1
   (1. 0 mark for this concept)
2. Proliferation of the bacillus causes destruction of bone, replacement with tuberculous granulomatous tubercle (caseous necrosis)
   (1. 5 marks for these concepts)
3. Vertebra weakens, then collapses, leading to herniation of disc material and contamination via direct extension

Question 2

Describe the pathology of the extremities and soft tissue in spondylitis (disco-vertebral)

Answer 2

Caseous necrosis with abscess formation is common.
Spread into adjacent tissues from the lumbar spine particularly
spreading beneath the psoas muscular sheath distally,
presenting as a tumour (necrotic tissue filled lump) in the groin
(1 mark for the concept on each line)

Question 3

Name and describe the five stages of an infectious disease (disease course)

Answer 3

1. Incubation period
    Pathogen begins active replication without symptoms.
2. Prodromal stage
    Appearance of initial symptoms, e.g. vague malaise, mod fever, myalgia (muscle pain), headache, etc.
3. Acute stage
    Maximum impact due to proliferation and dissemination of the pathogen.
    Symptoms are pronounced and specific.
4. Convalescent stage
    Containment of infection, elimination of pathogen, repair of damaged tissue.
5. Resolution
    Total elimination of pathogen.
    Could develop in chronic disease.
   (0.5 mark for the name of each stage, and 0.5 mark for any appropriate description of the stage)

Question 4

A 65 year old male presents complaining of constant dull back pain. He has a history of prostate cancer.

List six behavioural characteristics of malignant cancer cells (3 marks)

Answer 4

Loss of contact inhibition
Decreased cell-to-cell adhesions
Increased motility 
Immortality
Produce specific tumor antigens
Produce cancer degrading enzymes
Can produce ectopic hormones.
Metastasize
(0.5 mark for any 6 characteristics)

Question 5

Describe the haematological spread of metastatic cancer cells.

Answer 5

To metastasize to an unrelated distant site a cell must
1. break loose from primary tumor → 2. Secrete enzymes (breakdown matrix) to invade surrounding tissue → 3. gain access to a blood vessel → 4. survive its passage in the blood stream by avoiding host immune response by combining with blood components → 5. emerge from the blood stream at a favorable location by express specific surface attachment factors to recognize and attach to specific secondary site → 6. grow at secondary site by triggering growth of cell and stimulate new blood vessels to grow.
(1 mark for the description of each concept numbered)

Question 6

You are requested to x ray his lumbar spine.

Name and describe the distinctive radiographic features of metastatic bone disease from this type of cancer.

Answer 6

OSTEOBLASTIC (15%)
(0.5 mark for the name)
easier to identify, though their margins are usually ill defined
diffuse scattered pattern resembling “snowballs”
not detectable on plain film until 30% destruction of bone
(0.5 mark for each point)