Epstein-Barr virus-associated smooth muscle tumours after transplantation, infection with human immunodeficiency virus and congenital immunodeficiency syndromes.

Smooth muscle tumours (SMT) after transplantation (PTSMT) or associated with congenital immunodeficiency syndromes (CI-SMT) and human immunodeficiency virus (HIV-SMT) are rare. The majority of PTSMT and CI-SMT are associated with Epstein-Barr virus (EBV), while some HIV-SMT can be EBV-negative. SMT in immunodeficient states may present with unspecific symptoms which are mainly related to tumour localisation. In PTSMT, >50% of tumours manifest in the liver/transplant liver, but in general PTSMT, HIV-SMT and CI-SMT can occur at any site as single or multiple tumours. Multiple tumour manifestations do not define metastatic disease as PTSMT can occur synchronously and/or metachronously. PTSMT can originate from the recipient as well as from the donor. Morphologically, most tumours, in particular PTSMT, lack marked histological atypia or tumour necrosis, while some HIV-SMT and CI-SMT can present as sarcoma-like variants, but histomorphology does not predict clinical aggressiveness or tumourbiological behaviour. In PTSMT, surgery and reduced immunosuppression show comparable overall survival rates, while poor prognosis is mainly associated with intracranial manifestation and non-resectable tumours. In HIV-SMT and CI-SMT, surgery should be performed. In all 3 tumour types, adverse prognosis is mainly related to comorbidities associated with immunosuppression but not with the extent of histological atypia or tumour size.