Differential Diagnosis for Petrous Apex Lesion
Single Most Likely Diagnosis
- Cholesterol granuloma: This is the most likely diagnosis due to the characteristic imaging findings of iso-intensity on T1, hyper-intensity on T2, and homogenous enhancement with gadolinium. Cholesterol granulomas are known to occur in the petrous apex and have a typical appearance on MRI.
Other Likely Diagnoses
- Chondrosarcoma: This is a possible diagnosis, as chondrosarcomas can occur in the petrous apex and may show similar imaging characteristics, including hyper-intensity on T2 and enhancement with gadolinium. However, they often have a more heterogeneous appearance and may contain calcifications.
- Meningioma: Meningiomas can also occur in the petrous apex and may show homogenous enhancement with gadolinium. However, they are often iso- to hypo-intense on T2, which makes this diagnosis less likely given the hyper-intensity on T2 in this case.
- Cholesteatoma: This is a possible diagnosis, although it is less likely than cholesterol granuloma. Cholesteatomas can occur in the petrous apex and may show hyper-intensity on T2, but they often have a more heterogeneous appearance and may contain erosive changes in the surrounding bone.
Do Not Miss Diagnoses
- Malignant tumor (e.g. metastasis, lymphoma): Although less likely, it is essential to consider malignant tumors in the differential diagnosis, as they can have aggressive consequences if missed. These tumors may show similar imaging characteristics, including enhancement with gadolinium, and can be iso- to hyper-intense on T2.
Rare Diagnoses
- Petrous apex cyst: This is a rare diagnosis, but it can occur in the petrous apex and may show similar imaging characteristics, including hyper-intensity on T2 and enhancement with gadolinium.
- Lipoma: This is a rare diagnosis, but it can occur in the petrous apex and may show characteristic imaging findings, including hyper-intensity on T1 and T2, and minimal enhancement with gadolinium.
- Hemangioma: This is a rare diagnosis, but it can occur in the petrous apex and may show characteristic imaging findings, including a "honeycomb" appearance on T2 and enhancement with gadolinium.