Antral sign is seen in
Anterior bowing of the posterior wall of maxillary sinus often called antral sign or Holman-Miller sign, which is pathognomic of angiofibroma. (Ref: Diseases of ear, nose and throat, PL Dhingra, 7th edition, page 281)
Juvenile angiofibroma
Otosclerosis
CSOM
Sinusitis
Pharynx