Congenital Conditions

Question 1

Activation mutation of FGFR3

Answer 1

Achondroplasia (no problem with intramembranous bone formation)

Question 2

Osteogenesis Imperfecta

Answer 2

Commonly from Au Dom defect in collagen type I synthesis

Question 3

Osteopetrosis

Answer 3

Abnormally thick bone that fractures easily, due to poor osteoclast fxn, CA II mutation high yield (loss of acidic environment necessary for bone resorption). Anemia, bone fx, thrombocytopenia, leukopenia, vision and hearing impairment, hydrocephalus, RTA with CA II mut. Tx with BM transplant

Question 4

HOXD13

Answer 4

brachydactyly - short, broad, terminal phalanges of thumb and 1st toe

Question 5

SOX9

Answer 5

campomelic dysplasia - short bowing long bones, small chest cavity, respiratory failure, sex reversal

Question 6

RUNX2

Answer 6

cleidocranial dysplasia - loss of fxn mutation - patent fontanelle, wormian bones, short stature, delayed secondary teeth, primitive clavicle

Question 7

TBX5

Answer 7

Holt-Oram Syndrome- cardiac atrial septal defect, thumb wrist and forearm hypoplasia

Question 8

LMX1B

Answer 8

Nail and Patella Syndrome - hypoplastic nails and patella, dislocated radial head, progressive nephropathy

Question 9

PAX3

Answer 9

Waardenburg Syndrome- different eye colors, partial albinism, hearing loss, white streak hair, constipation

Question 10

COL2A1

Answer 10

Achondrogenesis type 2 - short trunk (type 2 collagen)

Question 11

COL10A1

Answer 11

Metaphyseal Dysplasia Schmid Type - short stature (type 10 collagen)

Question 12

Mazabraud Syndrome

Answer 12

Fibrous dysplasia and soft tissue myxomas

Question 13

McCune-Albright Syndrome

Answer 13

polyostotic fibrous dysplasia, cafe au lait spots, endocrine issues including precocious puberty GNAS1

Question 14

Gain of Fxn mut in GNAS1

Answer 14

Fibrous dysplasia

Question 15

“Chinese Letters”

Answer 15

Fibrous dysplasia - poorly formed islets and trabeculae of woven bone, curvilinear shapes with no rim of osteoblasts

Question 16

HFGFR3 Receptor

Answer 16

thanatophoric dysplasia - severe limb shortening and bowing, small chest cavity, respiratory failure

Question 17

Fibrous Cortical Defect

Answer 17

eccentric, sharply delineated, developmental metaphyseal lesion in long bones. AKA benign fibrous histiocytoma if mass involves medulla. Non-ossifying fibroma if >5cm.

Question 18

storiform - woven mat pattern

Answer 18

fibrous cortical defect - macrophages and fibroblasts, macros with foamy cytoplasm, may be clustered or multinucleated.

Question 19

sharply demarcated radiolucency with a long axis parallel to the cortex surrounded by a thin rim of sclerosis

Answer 19

radiograph to diagnose fibrous cortical defect