Part 2: PTLD

Diagnosis

Part 2: PTLD

History

Seventeen year old teenager (same patient than part 1).  Heart transplant one year before exam. Abdominal pain and fatigue. Rule out PTLD.

Findings

Large abdominal hypermetabolic mass located near sigmoid (SUV max 10). There is hypermetabolism in the periphery of the lesion; the center is hypometabolic. No FDG-avid lymph node.

There is a urinary stasis in the right kidney, especially in the cortex. The right kidney is mildly larger than the left. There is a pelvic dilation in comparison to the other side. This is likely related to an acute obstruction from the mass.

DDx

PTLD

GIST

Sarcoma

Abcess

Discussion

PTLD refers to a heterogeneous group of lymphoproliferative disease that develops as a consequence of immunosuppression in transplanted recipient, particularly  with solid organs. EBV seems to play an important role in this disorder. EBV infected B-cell are normally in a latency state in immunocompetent, because of the cytotoxic T-cell surveillance. With immunosuppression, this T-cell system is reduced and probability of uncontrolled proliferation of EBV infected B-cell increases.

PTLD in children occurs more frequently in the first two years after transplantation, during the most immunosuppressive period. There are three major risk factors associated with PTLD: EBV status at the time of transplant, age and organ transplant. An EBV-seronegative recipient receiving an EBV-positive allograft is the most significant risk factor. Young age is an independent risk factor. The heart-lung transplant has the highest risk while renal transplant has the least in solid transplant.

The 2008 WHO classifies PTLD in four groups:

-Early lesion

-Polymorphic PTLD

-Monomorphic PTLD (subdivided in lymphoma they resemble, most commonly diffuse large B cell and Burkitt lymphoma)

-Classical Hodgkin lymphoma type PTLD

Discrimination between types are made through pathological findings. Early lesions tend to regress with reduction of immune suppression. Polymorphic PTLD may also regress with reduction of immune suppression. A proportion of polymorphic PTLD and numerous monomorphic PTLD needsadditional therapy such as monoclonal antibody (anti CD-20) and chemotherapy.

In PTLD, there is more extra nodal involvement, especially in the abdomen than in lymphoma of immunocompetent patients. Early disease can be found in the tonsils and adenoids, making the diagnosis with PET-FDG difficult, due to physiological uptake in the ENT region.  

Roles of TEP-FDG are similar than in conventional lymphomas. It is useful for staging purposes and establishing response to therapy. It can also targets the easiest/best lesion to biopsy. Moreover, one report suggested that most aggressive subtypes (monomorphic PTLD) demonstrate higher metabolic activity.

References

Scarsbrook et al. : Post-transplantation lymphoproliferative disorder: the spectrum of imaging appearances. Clin Radiol. 2005 Jan;60(1):47-55

Thomas et al. : Epstein-Barr virus mimicking lymphoma on FDG-PET/CT. Clin Nucl Med. 2009 Dec;34(12):891-3

Glotz et al. : The Seville expert workshop for progress in posttransplant lymphoproliferative disorders. Transplantation. 2012 Oct 27;94(8):784-93

Wistinghausen et al. : Post-transplant lymphoproliferative disease in pediatric solid organ transplant recipients. Pediatr Hematol Oncol. 2013 Sep;30(6):520-31

Takehana et al. : (18)F-FDG PET/CT in the management of patients with post-transplant lymphoproliferative disorder. Nucl Med Commun. 2014 Mar;35(3):276-81

Panagiotidis et al. : (18)F-fluorodeoxyglucose positron emission tomography/computed tomography in diagnosis of post-transplant lymphoproliferative disorder. Leuk Lymphoma. 2014 Mar;55(3):515-9

Metser et al. : FDG-PET/CT in abdominal post-transplant lymphoproliferative disease. Br J Radiol. 2016 Jan;89(1057):20150844

Vali et al. : The value of (18) F-FDG PET in pediatric patients with post-transplant lymphoproliferative disorder at initial diagnosis. Pediatr Transplant. 2015 Dec;19(8):932-9

Yoon et al. : Posttransplant Lymphoproliferative Disorder of the Thorax: CT and FDG-PET Features in a Single Tertiary Referral Center. Medicine (Baltimore). 2015 Aug;94(31):e1274