May Be Caused by

 Common

Cholesteatoma

Cholesterol granuloma

Chronic otitis media

Mastoiditis

Temporal bone fracture

 Uncommon

Bone neoplasm

Carcinoma of external auditory meatus

Carcinoma of mastoid

Carcinoma of middle ear

Ceruminous gland tumor

Dermoid cyst

Embryonal rhabdomyosarcoma

Epidural mastoid cyst

Epidural mastoid pneumatocele

Glomus jugulare tumor

Glomus tympanicum tumor

Granuloma

Hemangioma

Keratosis obturans

Langerhans cell histiocytosis

Lymphoma

Malignant external otitis

Meningioma

Metastasis

Nasopharyngeal neoplasm

Postmastoidectomy meningocele

Postmastoidectomy meningoencephalocele

Sarcoidosis

Schwannoma

Syphilis

Tuberculosis

Venous malformation