A woman of 45, a known cause of pemphigus vulgaris on a regular treatment with controlled primary disease presented with pain in the right hip and knee. Examination revealed no limb length discrepancy but the patient has tenderness in the scarpa's triangle and limitation of abduction and internal rotation of the right hip joints as compared to the other side. The most probable diagnosis is -: (A) Stress fracture of neck of femur, (B) Avascular necrosis of femoral head, (C) Perthe's disease, (D) Transient synovitis of hip
Answer is B. This patient has


Pemphigus vulgaris taking treatment (steroid is the DOC).
Pain in hip and knee (Pain of hip can refer to hip).
Limitation of abduction & internal rotation.


Diagnosis is AVN of hip.