histopathology :part 3

Question 1

Describe the classification of bone as cortical and cancellous(Differennt macroscopic bone structure)

Answer 1

Cortical bulk of Long bones  80% of skeleton  Appendicular skeleton 80-90% calcified  Mainly mechanical and protective role

Cancellous bulk of complex bones like Vertebrae and pelvis  20% of skeleton  Axial 15-25% calcified  Mainly metabolic  Large surface

Question 2

What are the two types of bone biopsy?

Answer 2

Closed – needle – core biopsy with Jamshidi needle . Open – for sclerotic or inaccessible lesions

Question 3

What is metabolic bone disease?

Answer 3

it’s a group of diseases that in general cause reduced bone mass and strength due to an imbalance of various chemicals in the body be they vitamins, hormones, minerals, or whatever.•Cause altered bone cell activity, rate of mineralisation, or changes in bone structure

Question 4

What is used to investigate mineralisation?

Answer 4

Fluorescent tetracycline labelling

Question 5

List the four organs that are directly or indirectly affected by parathyroid hormone to control calcium metabolism.

Answer 5

Parathyroid glands Bones Kidneys Proximal small intestine

Question 6

State some causes of secondary hyperparathyroidism.

Answer 6

Chronic renal insufficiency Vitamin D deficiency

Question 7

Describe the histology of Paget’s disease.

Answer 7

Prominent reversal lines Masses of osteoclasts in the same site as osteoblasts

Question 8

Microsopic stucture of cortical bone

Answer 8

This is lamellar bone.. Cortical bone is made up of parallel osteons. Each circular structure shown here is an individual osteon of about 0.2mm diameter,surrounding a central canal called the haversian canal which contains the blood vessels.

At the periosteum there are circumfrential lamellae that go around the whole bone, there are interstillial lamellae between the osteons, and there is trabecular lamellae which do not surround a central channel but are organized into layers. You can see these dendritic structures found in lacunae in the lamellae. Those are bone cells called osteocytes and the processes from them are the osteocyte canalicular network that spans throughout the bone and is thought to form a mechanosensory network allowing the repair of damaged bone or remodeling of structure to respond to new stresses being place on a bone.

Question 9

What does this image show, what specific group of people is this for

Answer 9

Osteomalacia (rickets)

In children the inability to properly mineralise bone results in rickets with the characteristic widening of the growth plate and bowing of the long bones shown in this x-ray.

Question 12

What do mature osteoblasts produce that blocks the RANK/RANKL binding?

Answer 12

Osteoprotegrin

Question 13

How are bones classified anatomically?

Answer 13

Flat Long Cuboid/sohrt, irregular and ssamoid

Question 14

What are the clinical consequences of osteomalacia?

Answer 14

Bone pain/tenderness, Fracture (horizontal fractures at Looser’s zone at the neck of the femur are commonly seen) ,Proximal weakness ,Bone deformity

Question 15

What are the symptoms of hyperparathyroidism?

Answer 15

Stones, Bones, Abdominal Groans and Psychic Moans. Stones – calcium oxalate renal stones .Bones – osteitis fibrosa cystica .Abdominal Groans – acute pancreatitis. Psychic Moans – psychosis and depression.

Question 16

What is the most important investigation for hyperparathyroidism and what will it show in someone with hyperparathyroidism?

Answer 16

X-ray of the hand .Subperiosteal bone erosions. Brown cell tumours – small areas of resorption in the long bones of the fingers that are filled with osteoclasts

Question 17

List some clinical features of Paget’s disease.

Answer 17

Pain Microfractures, Nerve compression ,Skull changes, Deafness ,Haemodynamic changes, Cardiac failure, Hypercalcaemias, Development of sarcoma in the area of involvement

Question 19

Explain Renal Osteodystrophy

Answer 19

This is because of a failure to excrete phosphate and produce vitamin D. Secondary hyperparathyroidism may result to attempt to compensate leading to the signs of osteitis fibrosa cystica. Osteomalacia may be observed due to hypocalcemia, and there may also be osteoscelerosis, growth retardation or osteopososis apparent.