Porta hepatis lymphoproliferative disorder post liver transplantation

A 62-year-old man came to our institution because of jaundice, dark urine, light-coloured stool and itchiness. He had a history of liver transplantation 4 months prior due to cirrhosis complicated by hepatocellular carcinoma previously treated by transarterial chemoembolisation.

Ultrasounds examination (not shown) revealed intra and extrahepatic biliary dilatation. Portal vein, hepatic artery and hepatic veins were patent.

Magnetic resonance (MR) imaging confirmed the dilatation of the biliary tree above a long stenosis of the common bile duct (Fig. 1) caused by extrinsic compression from an hilar solid mass of approximately 40 mm, surrounding hilar vessels (Fig. 2). The mass showed unequivocal restricted diffusion (Fig. 3). It appeared slightly hypointense compared to liver parenchyma on T1-weighted images and showed irregular peripheral enhancement after Gadolinium injection, with no enhancement of the central portion (Figs. 4a-b).  Hepatic artery and portal vein were patents.

FDG PET CT revealed avid accumulation of the radiotracer at the periphery of the lesion (Fig. 5). The examination was performed 4 days after endoscopic biliary drainage by plastic stents.

The diagnosis was confirmed by biopsy.

Background

Post-transplant lymphoproliferative disorder (PTLD) is heterogeneous lymphoid disorder ranging from relative benign lymphoid hyperplasia to poorly differentiated lymphoma [1]). PTLD is the second most common tumour in adult transplant recipients and the first most common in childhood [2]. It may occur after any solid organ transplantation and its frequency ranges from 1-2 % after kidney transplantation up to 10% following thoracic organ transplantation,  depending on the type of allograft used and immunosuppressive regimen [3]. PTLD occurs in 1%-3% of liver transplant recipients [4].  PTLD has a bimodal manifestation, with most cases occurring within the first year after transplantation and a second peak occurring 4-5 years after transplantation [1]. The Epstein-Barr virus (EBV) genome is found in the majority (>90%) of B-cell PTLD occurring early after solid organ transplantation [5].

Clinical Perspective

Clinical presentation is variable and it depends on disease location. Patients are often asymptomatic or they present nonspecific symptoms, especially weight loss, fever or night sweats, abdominal pain, anorexia, nausea or vomiting. A mass visible at imaging may be the first clue to diagnosis [1,5]. Fulminant presentation with a systemic disease is life-threatening.

Imaging Perspective

PTLD can have a varied appearance at imaging. It may be nodal or extra-nodal. The nodal category is defined by lymphadenopathy. The extra-nodal category is defined by disease located in gastrointestinal tract, solid organ or central nervous system. In general, PTLD most commonly involves the allograft itself or the graft region for non-renal allografts.  There are four patterns for solid organ category: obstructive, hilar or solitary mass, parenchymal and infiltrative. At MR imaging, PTLD usually has low signal intensity on T1-weighted and T2-weighted imaging. At contrast-enhanced CT or MR imaging, tumours related to PTLD are typically hypoenhancing.

PET normally depicts increased FDG uptake. The diagnosis of PTLD requires tissue examination [1].

Outcome

Treatment options include reducing immunosuppression, chemotherapy, radiation therapy, rituximab therapy or surgical resection, depending on the subtype, distribution and the type of transplanted organ [6].

Take-Home Message/Teaching Points

PTLD is an uncommon complication of transplantation that can lead to significative morbidity and mortality.  It may involve any of the organ system with disease manifestation depending on the type of transplantation. Its clinical presentation and appearance at imaging can vary. The final diagnosis requires tissue sampling because knowledge of the PTLD subtype is needed for appropriate treatment. The radiologist plays a pivotal role in making an early diagnosis and in targeting biopsy [7]