2012 Radiology Exam - Musculoskeletal Case 2

History: 13 year old American Paint Horse gelding presented for left front lameness and recurrent hoof abscess

Images: 4 films, left front foot

Smooth, well marginated focal radiolucent defect in palmar medial aspect of P3 solar margin best seen on DMPaLO, Mild flattening on DPA on medial aspect of P3.  
Keratoma is most likely differential. Focal osteomyelitis less acceptable as the smooth defect is more consistent with pressure atrophy.  
In general, candidates did well with this case. Full credit was given if keratoma was the first (or only) differential. Candidates lost points if focal osteomyelitis/pedal osteitis was listed as the first differential, and lost more points if keratoma was not mentioned.