Case 9
History:
An 18-month-old infant presented with a history of acute right-sided mastoiditis.
Findings:
Lateral view of the skull shows oteolytic area involving the right temporal bone. Axial CT images demonstrate an enhancing soft tissue mass with destruction of the inner and outer tables of the mastoid portion of the right temporal bone. Similar findings are depicted on the axial pre and post gadolinium T1 WI. Note that there is no involvement of the adjacent subcutaneous soft tissue, differentiating it from mastoiditis. The lesion is slightly hypointense in T2 WI.
Diagnosis:
Eosinophilic granuloma
Discussion:
Eosinophilic granuloma (EG) is predominantly seen in children and young adults. The skull is a common site of involvement. In the head and neck region, these lesions commonly involve the jaw or temporal bone. Temporal bone lesions can be bilateral in up to 30% of cases.
CT shows destruction of the temporal bone. The lesions have indistinct margins, and the smaller structures of the bony labyrinth and auditory ossicular chain may show erosion. Post-contrast images show associated soft tissue mass enhancement. On MR, these masses can hyperintense on T2WI and variable signal intensity on T1WI. Edema and inflammation around the lesion can also be seen. Enhancement is seen after administration of gost-gadolinium.
The differential diagnosis should include cholesteatoma, mastoiditis, rhabdomyosarcoma and metastatic lesions, among others.
References:
- Prayer D, Grois N, Prosch H, Gadner H, Barkovich AJ: MRI imaging presentation of intracranial disease associated with Langerhans cell histiocytosis. AJNR Am J Neuroradiol. 2004 May;25(5):880-89
- Koch BL: Langerhans histiocytosis of temporal bone: role of magnetic resonance imaging. Top Magn Reson Imaging 2000Feb; 11(1):66-74.
- Goldsmith AJ, Myssiorek D, Valderrama E, Patel M: Unifocal Langerhans’ cell histiocytosis (eosinophilic granuloma) of the temporal bone. Arch Otolaryngol Head Neck Surg 1993 Jan;119:113-116.
