This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Skeletal System, Subject name: Radiology
"Looser's zone" are seen in: 
Select and explain. 
A. Osteogenesis imperfecta, B. Osteopetrosis, C. Osteomalacia, D. Hypoparathyroidism
C: Osteomalacia
Answer: C: Osteomalacia 
Explanation: Ans. c (Osteomalacia). (Ref. Grainger, Diagnostic Radiology, 4th/ pg. l933, 1949).MBKMAN'S FRACTURE/ LOOSER'S ZONE/ UMBAU ZONE/ PSEUDO FRACTURE# Focal accumulations of osteoid are seen in compact bone at right angles to long axis; radiographically, these are known as Looser's zones or pseudofractures or umbau zones# Exact cause of looser's zones is unclear, although they probably represent partial insufficiency fractures.# It is a distinguishing sign of osteomalacia, although they may occur rarely also in:- Paget's disease- Fibrous dysplasia- Osteoporosis (rarely)- Hyperphosphatasia- Osteogenesis imperfecta# They are symmetrically distributed & occur principally in:- Pubic rami,- femoral necks,- scapulae,- ribs,- long bones,- metatarsals.# Other key imaging features of osteomalacia is:- Osteopenia,- intracortical resorption (cortical tunneling),- coarsened, indistinct trabecular pattern,- bowing of bones,- true fractures, especially at the femoral neck.