CLINICAL QUIZ Submandibular lymphadenopathy in a child post-renal transplant—BWhat lies beneath?!^: Answers Gurinder Kumar 1 & Mohammed Khair Al Ghabra 1 & Sadia Hafez Ilyas 1 & Vasudev Omprakash Sharma 2 & Naser Al Zein 3 & Eihab Al Khasawneh 1 Received: 23 November 2017 /Accepted: 24 November 2017 # IPNA 2018 Keywords Renal transplantation . Lymphadenopathy . Kaposi sarcoma Answers 1. The differential diagnosis to be considered for cervical/ submandibular lymphadenopathy in a child post-renal transplant is as follows: a) Post-transplant lymphoproliferative disorder: usually associated with an Epstein–Barr virus infection. It may be insidious, resembling infectious mononucle- osis, or it can present as an aggressive form of lymphoma. b) In an immunosuppressed child presenting with fever, pharyngitis, and cervical lymphadenopathy, the dif- ferential diagnosis may include streptococcal infec- tion and infectious mononucleosis. c) Tuberculosis. d) Kikuchi–Fujimoto disease: rare benign and self- limiting disease with a worldwide distribution and higher prevalence in the Asian population, character- ized by regional cervical lymphadenopathy accompa- nied by mild fever and night sweats. e) Viral lymphadenitis. f) Human immunodeficiency virus infection. g) Kaposi’ s sarcoma. 2. Histopathology demonstrated a lymph node that was completely replaced by a metastatic tumor. Fig. 1 shows metastatic Kaposi ’s sarcoma (KS) —H&E (×200) stain displays bland spindle cell proliferation with slit-like spaces in between that contain red blood cells. Lymphoid cells are seen at one end. Fig. 2 shows immunohistochemistry (×200) where the spindle cells are strongly and diffusely positive for human herpesvirus-8 (HHV8), confirming KS. Ancillary stud- ies (immunohistochemistry): CD34-positive, HHV8- positive, S100-positive in the dendritic cells. Smooth muscle actin/creatine kinase (CK) and AE1/AE3/CK5/ 6 were negative. Hence, the findings were consistent with metastatic KS. 3. Management of KS of the lymph node involves reduc- tion of immunosuppression, which is the initial man- agement strategy. Changing the immunosuppression from calcineurin inhibitors to an mTOR inhibitor such as sirolimus can be considered because of its dual ac- tion of inhibiting the progression of KS and as an anti- rejection medication. Discussion Post-renal transplantation exposes patients to chronic long- term immunosuppression and 10–30% of deaths are attributed to post-transplant malignancy [1]. KS is one of the most com- mon malignancies to occur in post-renal transplant recipients and reported worldwide after the first description in 1872. There are four epidemiological forms of KS, including classic, This refers to the article that can be found at https://doi.org/10.1007/ s00467-017-3859-1 * Gurinder Kumar kumargurinder@gmail.com 1 Division of Paediatric Nephrology, Sheikh Khalifa Medical City, Abu Dhabi, United Arab Emirates 2 Department of Pathology, Sheikh Khalifa Medical City, Abu Dhabi, United Arab Emirates 3 Division of Paediatric Hematology, Sheikh Khalifa Medical City, Abu Dhabi, United Arab Emirates Pediatric Nephrology https://doi.org/10.1007/s00467-017-3861-7