Large Subtentorial Extraaxial Intracranial Mass: our Case of the Month April, 2024

 COMPUTED TOMOGRAPHIC FINDINGS

 The CT study reveals an extraaxial intracranial mass within the caudal cranial fossa. The mass is in a subtentorial position and measures 16mm in length, 13mm in height, and 15mm in width. Moderate nonuniform contrast enhancement is seen. The exhibits hyperattenuating areas on the plain scan. Mild hyperostosis of the osseous tentorium of the cerebellum is noted. 

Both tympanic bullae contain a moderate amount of fluid attenuating material, L>R. Thickening of the mucosal lining of the right and left tympanic bullae is seen. The osseous lining is smooth and thin. A moderate amount of hypoattenuating contrast negative material is seen within the medial aspect of the left external auditory meatus. The right external auditory meatus presents within normal limits at this time. 

The regional lymph nodes in the retropharyngeal space present mild symmetric enlargement. 

Multiple metal opaque bullet fragments are seen within the left nasal cavity and circumferential to the left maxilla and temporomandibular joint. No evidence of osseous injury is noted; however, there is moderate atrophy of the left masseter muscle. 

COMPUTED TOMOGRAPHIC DIAGNOSIS

• Large extraaxial intracranial subtentorial mass with significant mass effect onto the cerebellum and cerebellar herniation. 
• Chronic bilateral otitis media. 
• Chronic left-hand sided otitis externa. 
• Mild bilateral retropharyngeal lymphadenomegaly compatible with reactive lymphadenitis. 
• Old air gun injury with left masticatory muscle atrophy. 

INTERPRETATION OF THE FINDINGS AND FURTHER RECOMMENDATIONS

 The CT study reveals a large subtentorial extraaxial intracranial mass. The findings are compatible with subtentorial meningioma. Round cell neoplasia is a potential but less likely differential diagnosis. Increased intracranial pressure and foraminal herniation of the cerebellum have to be assumed. 

The CT study furthermore confirms presence of bilateral otitis media and left-hand sided otitis externa with reactive regional lymphadenitis and chronic traumatic injury secondary to multiple air gun bullet fragments in the region of the left mandible and left temporomandibular joint as well as within the left nasal cavity. The isolated masseter muscle atrophy indicates potential injury of one of the peripheral branches of the mandibular nerve and/or chronic disuse.