A case of methotrexate-related lymphoproliferative disease showing multiple liver lesions in a patient with rheumatoid arthritis

A 66-year-old woman with rheumatoid arthritis (RA) who had been receiving methotrexate (MTX) for 2 years presented with tarry stools. Contrast-enhanced computed tomography (CT) of the abdomen revealed irregular wall thickening in the ileocecal region and multiple low-contrast masses in both lobes of the liver. Lower gastrointestinal endoscopy revealed a type 2 tumor in the ileocecal region with a semi-peripheral ulcer. Histological examination of liver and colon biopsies showed other iatrogenic immunodeficiency-associated lymphoproliferative disorder (Oi-LPD), diffuse large B-cell lymphoma type, with positivity for Epstein-Barr virus DNA. After withdrawal of MTX, the LPD lesions disappeared and the patient achieved remission. We considered this to be a sporadic case of Oi-LPD, diffuse large B-cell lymphoma type, in the liver and colon due to treatment with MTX. There has been no previous report of this condition with simultaneous hepatic and colonic lesions, and the present case is thought to be highly informative in relation to the pathogenesis.


Introduction
Lymphoproliferative disorders (LPDs) arise in patients who have been treated with immunosuppressants, and diffuse large B-cell lymphoma (DLBCL) is the most common type.One such immunosuppressant, methotrexate (MTX), is the first choice for patients with rheumatoid arthritis (RA) [1,2].EBV reactivation associated with reduced immunocompetence is known to be responsible for the development of MTX-LPD.As MTX administration for RA tends to be prolonged, development of MTX-LPD is known to be a severe complication [3].Here we report our experience with a RA patient who developed MTX-LPD, DLBCL type, in the liver and colon.

Case presentation
A 66 year-old woman was admitted to our hospital with a 3 day history of tarry stools.She had RA and had been treated with salazosulfapyridine, iguratimod and MTX for 2 years.Her RA symptoms were well controlled.Her abdomen was flat, soft, and not tender.Severe anemia (hemoglobin 7.6 g/dL) was evident, and the serum levels of C-reactive protein and soluble interleukin-2 receptor were 9.19 mg/dL and 2,630 U/mL, respectively.Epstein-Barr virus (EBV) DNA was detected in the peripheral blood at 3.60 log IU/ml (Table 1).Contrast-enhanced CT revealed a mass with enhancement in the ileocecal region (Fig. 1A), and multiple nodular masses without enhancement in the liver and para-aortic region (Fig. 1B and C).Contrastenhanced magnetic resonance imaging (MRI) with gadolinium-ethoxybenzyl diethylenetriamine-pentaacetic acid (Gd-EOB-DTPA) showed multiple tumors in the liver with central necrosis (Fig. 1D-G).Lower gastrointestinal endoscopy revealed a mass in the ileocecal region which was suspected malignant tumor (Fig. 2).Liver metastasis of ileocecal cancer or malignant lymphoma was suspected, and ultrasound-guided biopsy of the liver tumors was performed.Histological examination of the liver and colon specimens revealed proliferation of CD20-positive large lymphoid cells with necrosis and in situ hybridization (ISH) demonstrated Epstein-Barr encoding region (EBER)-1 positivity.Histological examination showed diffuse proliferation of mostly large lymphoid cells with necrosis in the liver (Fig. 3A and  B) and colon, although there was no atypia in the epithelium of the surface mucosa of colon.Immunohistochemically, these large lymphoid cells were CD20 ( +) (Fig. 3C), CD30 ( +) (Fig. 3D), CD10 ( +) (Fig. 3E), CD 23 (−) (Fig. 3F), BCL2 (−) (Fig. 3G), BCL6 (−) (Fig. 3H), and MUM1 (−) (Fig. 3I).The Ki-67 labeling index was 80% (Fig. 3J).EBER positivity was detected by ISH (Fig. 3K).Immunostaining of biopsies from the colon yielded similar findings (Fig. 3L and  M).The final diagnosis was Oi-DLBCL based on the WHO classification revised fourth edition, as the multiple tumors began to shrink after MTX withdrawal.
Observation was continued, and CT of the abdomen four months later revealed spontaneous shrinkage of most of the tumors (Fig. 4A).The serum level of sIL-2R improved spontaneously (312 IU/ml), and EBV DNA in the peripheral blood decreased to less than the standard value.After the  withdrawal of MTX, the patient experienced no deterioration in her joints.There has been no sign of recurrence for 8 months (Fig. 4B and 5).

Discussion
RA patients are known to have a 2-to 4-fold higher incidence of malignant lymphoma as a complication than the general population [4].Although MTX is used as a firstline treatment for patients with RA, it carries a risk of LPD [2].When LPD occurs, biologics are often used in the RA patients as an alternative to MTX [5].LPD, including malignant lymphoma, has been found to occur in RA patients receiving MTX, and this is termed MTX-LPD.The WHO classifies it as immunodeficiency-associated LPD.EBV infection is said to be a complication in about half of MTX-LPD cases, and EBV reactivation has been implicated [6][7][8].
It is thought that the EBV gene releases factors similar to growth factors, transcription factors, and apoptosis inhibitors, causing B lymphocytes to transform into lymphoblasts, exhibiting tumor-like growth [9].The most common sites of MTX-LPD are lymph nodes [10] and tonsils [11], but thyroid [12], lung [13], liver [14], and colon lesions [15] have also been reported.
Imaging modalities, such as US and CT, can aid the diagnosis of hepatic lymphoma/MTX-LPD.A previous report has indicated that penetrating vessels running through the tumor visualized by US was helpful for diagnosis of hepatic lymphoma [16].In the present case, penetrating vessels running through the tumor were detected by CT scan.The evidence suggests that MTX-LPD should be considered in RA patients who are receiving MTX medications when CT or US shows a hepatic mass with signs of penetrating vessels.
In the listed MTX-LPD, DLBCL type cases (n = 8), MTX was discontinued and three of the patients achieved complete remission.Three additional patients achieved complete remission with chemotherapy.Two patients were treated by partial hepatectomy and had no recurrence.Two patients with MTX-LPD, Hodgkin lymphoma type, also stopped using MTX.One of them suffered relapse even after withdrawal of MTX, and the other underwent partial hepatectomy and had no recurrence.Our present patient achieved complete remission after MTX had been withdrawn.These findings suggest that immediate withdrawal of MTX is recommended for patients with hepatic MTX-LPD, DLBCL type.Our patient had two lesions; these may have been concurrent, or one may have been due to metastasis from the colon to the liver.Because of the multiple lymph node metastases and the histological similarities of the lesions, the possibility that the colon lesion had metastasized to the liver could not be ruled out.To our knowledge, this is the first case of MTX-LPD involving both the liver and colon to have been reported in English.

Conclusion
We have experienced a case of MTX-LPD, DLBCL type, in which multiple liver masses and colon lesions were concurrent.Multiple systemic masses in RA patients receiving MTX are suggestive of MTX-LPD, and early discontinuation of MTX should be considered.

Fig. 1 Fig. 2 Fig. 3 Fig. 4
Fig. 2 Lower gastrointestinal endoscopy.Lower gastrointestinal endoscopy revealed a mass in the ileocecal region which was suspected malignant tumor

Fig. 5
Fig. 5 Lower gastrointestinal endoscopy after methotrexate withdrawal.The tumor in the ileocecal region disappeared 8 months later

Table 1
Laboratory data of the present case at the time of hospitalization PIVKA-II protein induced by Vitamin K absence or antagonist, sIL-2R soluble interleukin-2 receptor

Table 2
Reported cases of rheumatoid arthritis patients with methotrexate-related lymphoproliferative disease in the liver