Petrous Bone Eosinophilic Granuloma

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Eosinophilic granuloma is a lytic lesion, driving from histiocyte proliferation of the bone. The lesions mostly occur in long bones, rib or skull, but the involvement of temporal bones is rare. We report the case of a 4-year-old girl with isolated eosinophilic granuloma of petrous apex, presenting with fever and right abducens paralysis. Eosinophilic granuloma is a lytic lesion, driving from histiocyte proliferation of the bone and is a form of Langerhans Cell Histiocytosis (LCH) that is classified into three spectrums of diseases: Letterer Siwe disease, Hand schuller Christian syndrome and Eosinophilic granuloma. These three patterns of disease have specific clinical manifestation.

Eosinophilic granuloma might be confused with chronic otitis media, external otitis and chronic mastoiditis. It usually occurs before the age of ten years and has been reported in skull, spine, ribs, femur and pelvis.Treatment includes curettage, radiation, radiosurgery and injection of steroid in lesions.In this report we present a 4 year old girl with petrous apex Eosinophilic granuloma. A 4-year-old girl was referred to the infectious ward of Children Medical Center, the referral pediatric center in Tehran, Iran from ENT ward with diagnosis of mastoiditis. She had a history of fever and headache for one month and right eye internal deviation for fifteen days before admission to ENT department. Her CT scan which was done in ENT ward revealed a destructive lesion on the tip of petrous bone due to petrositis (Figures 1 & 2). Brain MRI revealed the increase of signal in air cells of mastoid and right petrous apex in T2 that suggested right mastoiditis and AOM (Figures 3 & 4).

On admission in our department she had fever without headache and vomiting. A complete examination showed that her ears were normal but she had abducens paralysis in right side and other exam was normal. The results of initial laboratory tests were as follows: WBC=8040/mm3, neutrophils=47/8%, lymphocytes=42/2%, hemoglobin=10/6g/dl, Platelet=456000/mm3.