Bone Pathology

Question 1

• Hematogenous spread by bacteremia from trivial causes
• Causes worm eaten lytic lesions showing necrotic resorbing bone masses used as a scaffold by osteoblasts to form new bone
  
  • Marrow spaces replaced by pus

Answer 1

Osteomyelitis

Question 2

• Type 1 collagen is defective with inadequate bone formation resulting in thin cortices and trabeculae
• Mistaken for child abuse
• Autosomal Dominant
• Feature: dentinogenesis imperfecta and blue sclera

Answer 2

Osteogenesis Imperfecta

Question 3

• Osteoclasts lack the ability to remodel bone, causing obliteration of marrow space
• Marrow crowded out, causing myelophthisic anemia and extramedullary hematopoiesis with hepatosplenomegaly
• Deafness and Blindness due to constricted nerve ostea
• Dense bone easily infected causing osteomyelitis
• Autosomal Dominant most common and compatible with survival
• Autosomal Recessive causes death by anemia

Answer 3

Osteopetrosis - Marble Bone Ds

Question 4

Explain how Estrogen is protective in Osteoporosis of Post-Menopausal Women.

Answer 4

• Counter acts cytokines (IL-1, 6, TNF) by monocytes that cause resorption by:
  
  • Augmenting RANK receptor
  • Recruiting osteoclasts
• Stimulates OPG (inhibits osteoclasts)

Question 5

• Spontaneous wedge shaped infact of medullary subchondral bone mostly in the head of femur

Answer 5

Aseptic (Avascular) Necrosis

Question 6

• Increased remodleing not in response to physiological demands
• Increased thickness of architecturally weak bone
• ​Disease of Elderly
• Cause - paramyxovirus
• Cotton wool appearance in skull
• Increase in skull (hat) size
• Maxillary expansion
• Complication of High CO Failure
• Dx - elevated alkaline phosphatase

Answer 6

Paget Disease - Osteitis Deformans

Question 7

• Develpmental bone disease of continued production of immature bone matrix
• A switch for bone growth is turned on
  
  • Non-heritable somatic mutation
  • Continual production of cAMP (causes bone matrix formation)
• Severity depends on how early in embryogenesis the mutation occurs
• Begins in childhood, stopping after growth spurt
• Chinese Character Lettering - trabeculae form without regard to physiologic demands
• Woven bone matrix forms metaplastically from stroma, without osteoblastic rimming

Answer 7

Fibrous Dysplasia

Question 8

What is the worst form of Fibrous Dysplasia?

Answer 8

Albright Sx - severe polyostotic (many bones affected) fibrous dysplasia + precocious puberty in females; mutation occurs in the embryo

Question 9

• X-linked Dominant
• Kidney can’t resorb phosphate (it is excreted in urine)
• Short stature
• Elongated pulp horns stretch all the way to the DEJ, resulting in exposure upon tx

Answer 9

Vitamin D Resistant Rickets - Hypophosphatemia

Question 10

• Deficiency of tissue alkaline phosphatase
• Hammared copper skull appearance
• Wide pulp canals
• Early deciduous tooth loss due to lack of cementum
• Dx Tests:
  
  • urinary phosphoethanolamine
  • Low serum alkaline phosphatase

Answer 10

Hypophosphatasia

Question 11

• Adenoma secreting PTH, causing hypercalcemia
• Ca is leached out of the bone into the blood, leaving rarefied bone or giant cell lesions composed of osteoclasts (brown tumor)
• High serum Ca –> Metastic calcification with:
  
  • depostion in kidneys, pancreatic ducts
  • causes gastrin secretion (peptic ulcers)

Answer 11

Primary Hyperparathyroidism

Question 12

• Compensatory PTH release triggered by low serum Ca, usually due to phosphate retention seen in kidney failure

Answer 12

Secondary Hyperparathyroidism

Question 13

• Benign neoplasm of bone
• Tumor composed of mature bone
• Projects as a slow growing bony mass
• Multiple osteomas of facial and jaw bones signal Gardner Sx

Answer 13

Osteoma

Question 14

• Small tumor, not clinically noted
• Long bones, rarely jaws
• Sever pain at night - relieved by aspirn
  
  • Pain produced by prostaglandin E produced by osteoblasts
• Men age 10-20
• Histology shows osteoblasts producing bone

Answer 14

Osteoid Osteoma

Question 15

• Large tumor
• Most cases in spine; some in jaws
• Dull Pain - not relieved by aspirin
• Men age 10-20
• Histology shows osteoblasts producing bone

Answer 15

Osteoblastoma

Question 16

• Malignant neoplasm of bone
• 2nd decade
• Genetic mutation of RB gene
• Knee most common site
• Sunburst appearance on x-ray due to reactive periosteal bone formation
• Spreads through blood to lungs

Answer 16

Osteosarcoma

Question 17

• Men > 40
• Central portion of the body; axial skeleton
• Mesenchymal Variant - occurs in JAWS in YOUNG people and is very aggressive

Answer 17

Chondrosarcoma

Question 18

• Malignant neoplasm of plasma
• Most common primary tumor of bone

Answer 18

Multiple Myeloma

Question 19

• Malignant neoplasm of precursors of neuroblasts
• Chromosomal translocations produce oncoproteins that stimulate cell growth
• Small round cell tumor of medullary portion of bone, particularly in white male chlidren
• Most in leg bones and pelvis
• Grow rapidly
• X-ray - lytic lesion; cortex shows onion skinning of bone due to periosteal attempt to keep up with tumor growth

Answer 19

Ewing Sarcoma

Question 20

• Neoplasm of macrophages and osteoclasts
• Around knee joint; young to midle aged adults; NEVER IN JAWS
• Composed of sheets of mononuclear round cells (MACs) and Giant cells (osteoclasts)
  
  • Resemles brown tumor

Answer 20

Giant Cell Tumor

Question 21

Metastic cancers show up on X-rays as moth eaten lytic radiolucencys except prostate, which causes …

Answer 21

osteoblastic radiopaque metastases

Question 22

What is Osteoarthritis of the distal phalanges of women known as?

Answer 22

Heberden nodes

Question 23

Most common sarcoma of childhood, most in HandN, and GU system

Answer 23

Rhabdomyosarcoma (SKM)

Question 24

More common in women (uterus), skin, retroperitoneum

Answer 24

Leiomyosarcoma (SM)

Question 25

Most common sarcoma in adults, most in retroperitoneum

Answer 25

Liposarcoma (fat)