Mucous Retention Cyst of Mastoid Bone Mimicking Cholesteatoma

Primary mucocele of the mastoid: An incidental finding

“…Differential diagnosis of lesions causing erosion of the temporal bone includes inflammatory lesions such as cholesterol granuloma or cholesteatoma, extracranial cysts like epidermoid or dermoid cysts, intracranial lesions such as epidermoids or subarachnoidal cysts, histiocytosis, lymphoproliferative disorders, and solid tumors like schwannomas, tympanic‐jugular paragangliomas, meningiomas, gliomas, giant cell tumors, osteomas, ossifying fibromas chordomas, and primary or metastatic carcinomas …”

“…In case of mastoid mucoceles, surgical treatment is indicated because of their expansive tendency causing bone erosion and invasion of surrounding structures with the risk of developing infections and intra‐extracranial complications . Appropriate surgical treatment is complete removal of the lesion through mastoidectomy to reduce the risk of recurrence without increasing the risk of morbidity …”

“…12 Differential diagnosis of lesions causing erosion of the temporal bone includes inflammatory lesions such as cholesterol granuloma or cholesteatoma, extracranial cysts like epidermoid or dermoid cysts, intracranial lesions such as epidermoids or subarachnoidal cysts, histiocytosis, lymphoproliferative disorders, and solid tumors like schwannomas, tympanic-jugular paragangliomas, meningiomas, gliomas, giant cell tumors, osteomas, ossifying fibromas chordomas, and primary or metastatic carcinomas. 2,11,13 Adequate radiological assessment is based on CT and MR. Complete opacification, an enlarged cavity with bony defects, and sometimes peripheral calcifications and possible peripheral enhancement, if a contrast agent is administered, are the features seen by CT. 2,11 The MR signal is variable according to the proportions of water, mucus, and protein: A low signal in water-rich content and high signal in protein-rich content is evident in T1-weighted images, a high signal in water-rich content, and a low signal in protein-rich content in T2-weighted images.…”

“…Mucoceles can be primary or secondary to chronic inflammation, trauma, scarring from previous surgery, or radiotherapy and more rarely neoplasms. The obstruction of a natural drainage pathway is considered the pathogenetic basis of a mucocele, although a mucous retention cyst that gradually enlarges has been suggested as an alternative hypothesis in temporal bone . Within temporal bone, primary or secondary mucoceles have been only rarely observed with few descriptions prevalently in the mastoid .…”

“…The obstruction of a natural drainage pathway is considered the pathogenetic basis of a mucocele, although a mucous retention cyst that gradually enlarges has been suggested as an alternative hypothesis in temporal bone. 1,2 Within temporal bone, primary or secondary mucoceles have been only rarely observed with few descriptions prevalently in the mastoid. [1][2][3][4][5][6][7][8][9][10][11] We present a new case of primary mastoid mucocele that was an incidental finding during work-up for progressive sensorineural hearing loss.…”