Primary vitreoretinal natural killer/T-cell lymphoma with breast involvement: A case report and review of the literature.

A 50-year-old woman developed recurrent vitreous opacities in her left eye. The first diagnostic vitrectomy revealed no significant abnormality. Optical coherence tomography showed multiple high-density reflective nodules. The ratio of interleukin-6 to interleukin-10 was over 1 in her aqueous humor, and Epstein-Barr virus was present. A conventional immunohistochemistry examination of vitrectomy specimens was diffusely positive for CD2, CD3, and Ki-67. Highly metabolic nodules were found in her right breast on positron emission tomography-computed tomography scan. Immunohistochemistry of the breast biopsy was suggestive of natural killer/T-cell lymphoma. Considering the homology between the two lesions, combined with ancillary cytokine, cytology, and flow cytometry findings, the final diagnosis was primary vitreoretinal natural killer/T-cell lymphoma with involvement of the breast. The lymphoma resolved with chemotherapy, intravitreal injection of methotrexate, and ocular radiotherapy. This case shows that primary vitreoretinal natural killer/T-cell lymphoma can present with concomitant systemic involvement. We reviewed relevant published literature and summarized some new approaches that make the diagnosis easier and faster; however, the cytopathologic analysis of intraocular fluid is irreplaceable. An effective treatment strategy is still a matter of speculation.