Figure 1. The liver transplant is seen. The background metabolic activity of the liver is SUV_max 1.0. The spleen has moderately increased metabolic activity (SUV_max 2.0) and is slightly enlarged.

Figure 2. There is a markedly hypermetabolic (SUV_max 11.5) bulky soft tissue mass in the nasopharynx.

Figure 3. Bilateral hypermetabolic axillary lymph nodes are also present (SUV_max up to 2.7).

Figure 4. Bilateral moderately hypermetabolic inguinal lymph nodes are present (SUV_max up to 2.2).

Figure 5. In addition to the above, there is further hypermetabolic lymphadenopathy in the following regions: bilateral parapharyngeal, bilateral deep cervical, left supraclavicular fossa, mediastinum, para-aortic and mesentery. The right buccal mucosa has abnormal hypermetabolic activity. There is also mildly increased uptake in the bone marrow.

Post-transplant lymphoproliferative disease with lymphomatous infiltration of the nasopharynx, right upper buccal mucosa and spleen. There is lymphadenopathy involving the deep cervical, left supraclavicular, bilateral axillary, para-aortic, mesenteric and inguinal lymph nodes. The mild increase in bone marrow uptake may be reactive.

Post-transplant lymphoproliferative disease (PTLD) is the abnormal proliferation of lymphoid cells in immunocompromised organ transplant recipients, ranging from mild hyperplasia to malignant lymphoma. Approximately 85% is of B-cell origin, with a probable causal association with Epstein-Barr Virus (EBV) infection. FDG-PET/CT has been shown to be useful in both initial staging of the disease and in therapy monitoring for paediatric patients.