Bilateral simultaneous primary orbital lymphoma presenting with unilateral enophthalmos

A 73-year-old woman was examined for palpable orbital masses behind the right upper eyelid and left lower eyelid leading to entropion. Hertel exophthalmometry readings were 6.0 mm in the right eye and 11.0 mm in the left eye with a base of 102 mm. MRI revealed bilateral hypointense orbital soft-tissue masses. Pathologic evaluation of incisional biopsy specimens revealed malignant tissue composed of diffuse, mitotically active, atypical large lymphoid cells positive for CD-20 with immunohistochemical staining, confirming the diagnosis of malignant diffuse large B-cell lymphoma. Systemic survey was negative for extraorbital involvement. After R-CHOP chemotherapy (Rituximab 375 mg/m2 intravenously, Cyclophosphamide 750 mg/m2 intravenously, Doxorubicin 50 mg/m2 intravenously, Vincristine 1.4 mg/m2 intravenously, Prednisolone 100 mg orally), Hertel measurements were 9.0 mm in the right eye and 11.0 mm in the left eye. The mass lesions were totally regressed in follow-up MRI. Although rare, non-Hodgkin lymphoma may present bilaterally as primary orbital lesions and can unexpectedly cause enophthalmos instead of proptosis.