Epstein-Barr virus-positive iris diffuse large B-cell lymphoma detected by metagenomic next-generation sequencing

Ocular EBV infections have various clinical manifestations, including scleritis, posterior uveitis, retinal vasculopathy, retinitis, acute retinal necrosis, and intraocular lymphoma [2]. Although rare, the incidence of intraocular lymphoma has increased in recent years, but its etiology remains unknown. Herein, we report a case of a patient with EBV-positive DLBCL in the iris after undergoing penetrating keratoplasty. Through analysis of this special case, we were able to identify the cause of intraocular lymphoma.

First, the incidence of EBV-induced lymphoid or epithelial malignancies is well recognized [3]. Transmission of the virus occurs mainly through exposure to oral secretions, but EBV infection through organ transplantation has also been reported. The two main physiological targets of EBV are the epithelial cells and B lymphocytes. EBV replication occurs primarily in the epithelial cells and establishes a latent infection in the B lymphocytes, where it expresses limited sets of proteins called EBV transcription programs to efficiently transform B cells into lymphoblastic cells. In immunocompetent individuals, the levels of viral titers are determined by measuring the amount of EBV-specific cytotoxic T cells [4]. In normal histological structures, the iris possesses several epithelial cells and lymphocytes; therefore, it is prone to developing EBV-related lymphoma.

PIOL is considered to be a part of PCNSL. 15–20% of all PCNSL patients have PIOL at presentation; 50–90% of patients with PIOL develop a CNS and/or spinal cord disease after 16–24 months [5]. In 2011, the International PCNSL Collaborative Group published therapeutic principles for VRL. According to the group, systemic therapy is required if lymphoma lesions occur in the CNS and local therapy may be used if the disease is limited to the eye [6]. There is currently no standardized treatment plan for Epstein-Barr virus positive iris lymphoma in the literature [7, 8]. Because the lesion in our patient was relatively limited without systemic metastasis, the visual acuity of the left eye improved, and the white dense opacity in the vitreous cavity and retinal surface nodules completely disappeared after performing vitrectomy combined with long-term antiviral therapy and two intravitreal injections of MTX. In the subsequent treatment process, the patient was unwilling to cooperate with the examination and treatment due to personal reasons, and ultimately lost follow-up.

In addition, the patient received long-term ocular immunosuppressive therapy, including steroids and tacrolimus eye drops, after undergoing penetrating keratoplasty. Steroid eye drops can compromise the ocular immunity. Additionally, tacrolimus eye drops comprehensively inhibit the T-cell function in the eye. Collectively, these factors predisposed our patient to EBV infection in the ocular region.

Aside from ocular immune depression, aging-related systemic immunological deterioration is also one of the causes of EBV-positive DLBCL. The median age of patients with EBV-positive DLBCL was 71 years (range: 50–91 years) [9]. Age-related decline in cellular immunity is caused by several factors, including thymic atrophy, reduced output of new T lymphocytes, accumulation of anergic memory cells, deficiency in cytokine production, and uncertain antigen presentation [9]. Therefore, a decline in age-related immune function may also play a role in the occurrence and development of this disease.

To our knowledge, this case report is the first to document a case of a patient with an EBV-positive iris DLBCL; the diagnosis was established not only through pathological and immunohistochemical analyses, but also through metagenomic tests. In recent years, with the emerging of pathogen detection technology, mNGS has been increasingly used for the detection of various infections, such as bloodstream infection, [10] central infection, [11] and respiratory infection [12]. In eye infections, metagenomics also has some valuable applications, facilitating the prompt initiation of treatment with an optimal antimicrobial regimen [13, 14]. Metagenomic data do not only contain microorganism reads. Human sequences accounted for more than 95% of the mNGS data. Gu et al. [15, 16] reported that the homo reads in mNGS data could be used to identify tumor clues in body fluid and cerebrospinal fluid samples by conducting a copy number variation analysis. Based on the dual-analysis pipeline, mNGS can simultaneously analyze clues of infection and tumors. In this study, we identified a large number of EBV viruses using a metagenomic microbial analysis pipeline. Meanwhile, obvious chromosomal abnormalities, such as monosomy 6, were also identified in this sample, and the pathological results confirmed that the patient had EBV-positive iris DLBCL.

Although the patient’s diagnosis was confirmed, there was a need to differentiate it from other disorders. Post-transplant lymphoproliferative disorder (PTLD) is a malignancy with life-threatening complications occurring in recipients of both solid organ and hematopoietic stem cell allografts [17]. Lymphoma occurs as a result of B-cell proliferation after transplantation and is mostly caused by EBV infection [18]. The use of immunosuppressants leads to the depletion of EBV-specific T cells and disruption of the immune system balance, which eventually causes PTLD in transplant recipients [19]. Chen reported a case of a young patient who developed an iris tumor with mutton-fat keratic precipitates after undergoing a liver transplantation surgery; anterior uveitis and iris nodules were the most common ocular manifestations of PTLDs [20, 21] No study has reported a case of post-keratoplasty lymphoproliferative disorders; the clinical manifestations in our patient were not consistent with those of PTLD. Although the diagnosis of PTLD can be excluded, the negative effects of ocular immunosuppressants on the activation of intraocular viruses and the disruption of intraocular immune balance should be considered.

There are still some limitations in this case report, such as the short follow-up time in patients who have been treated and not been treated regularly in the hematology department. In this case, EBV infection, drug immunosuppression, and age-related immune deterioration may have played a role in the pathogenesis of EBV-positive iris DLBCL. EBV infection and the existence of chromosomal abnormalities in tumor cells were confirmed for the first time through metagenomic sequencing. This is a novel method for the diagnosis of intraocular tumors.