B Cell Lymphoma, Orbit
Findings:
Multiple MR images demonstrate a multilobulated heterogeneously enhancing mass along the right medial canthus with no definite invasion of ethmoid air cells. There is associated inflammatory signal within the ethmoid air cells which is of a different signal compared to the mass.
Discussion:
The differential diagnosis for this lesion includes lymphoma, metastasis, orbital pseudotumor, lacrimal sac neoplasm, or a soft tissue sarcoma. The imaging appearance of B-cell lymphoma is a nonspecific cellular lesion which typically has intermediate T2 signal, homogenous moderate enhancement, and is often extraconal. A lymphoma will typically mold to orbital structures without bone destruction or remodeling, which helps distinguish from a sarcoma. There is an overlapping appearance with other causes such as pseudotumor, sarcoidosis, Grave’s disease, and optic nerve tumors. The staging of lymphoma is based on the number of sites involved, whether it involves above or below the diaphragm, and/or is associated with disseminated disease. Up to 50% of these patients typically develop systemic disease, but less than 15% for stage one lesions. Site correlates with the risk of systemic disease, with two thirds of eyelid lesions eventually resulting in systemic disease. Low-grade lesions often respond to radiotherapy alone.