Botryoid Wilms tumor: a non-existent “entity” causing diagnostic and staging difficulties
Wilms tumors growing in a botryoid fashion into the renal pelvis have been reported since the 1960s as a rare tumor type usually associated with stromal histology and a good prognosis. However, the true frequency, association with Wilms tumor subtypes, and stage have never been comprehensively studied. We analyzed all Wilms tumors enrolled into the International Society of Paediatric Oncology (SIOP) United Kingdom 2001 Trial (2001–2011), which showed botryoid growth. In addition, we reviewed published series reporting papers on botryoid Wilms tumors. 77/739 patients (10.4%) showed at least one Wilms tumor with a botryoid pattern, and they were sub-classified according to the SIOP criteria as follows: 28 stromal, 21 mixed, 7 regressive, 3 completely necrotic, 4 blastemal, 2 epithelial, 3 diffuse anaplasia, 1 focal anaplasia, and 10 non-anaplastic type (treated with primary surgery). Stage was as follows: 25 stage I, 21 stage II, 12 stage III, 11 stage IV, and 8 stage V. In six cases, local pathologists incorrectly upstaged the tumor from stage I to stage II based on botryoid growth. The event-free and overall survivals were 90 and 96%, respectively. We concluded that botryoid growth pattern is a common finding in Wilms tumor and that all histological types and stages can share this feature. The botryoid growth itself is not a criterion for stage II. Botryoid Wilms tumor is not an entity but merely represents a pattern of tumor growth; such tumors should be sub-classified according to their overall histological features, which will determine treatment and prognosis.
KeywordsWilms tumor Botryoid growth Non-existent subtype
The authors thank the pediatric cancer teams from the UKCCLG cooperative centers who contributed case material and made this study possible as follows: Royal Aberdeen Children’s Hospital, Aberdeen, The Children’s Hospital, Birmingham, Addenbrooke’s Hospital, Cambridge, Royal Hospital for Sick Children, Edinburgh, Royal Hospital for Sick Children, Glasgow, Great Ormond Street Hospital for Sick Children, London, Royal Manchester Children’s Hospital, Manchester, Queen’s Medical Centre, Nottingham, John Radcliffe Hospital, Oxford, Southampton General Hospital, Southampton, Royal Hospital for Sick Children, Belfast, Royal Hospital for Sick Children, Bristol, Our Lady’s Hospital for Sick Children, Dublin, University Hospital of Wales Hospital, Cardiff, St. James’s University Hospital, Leeds, Royal Liverpool Children’s Hospital Alder Hey, Liverpool, Royal Victoria Infirmary, Newcastle, Sheffield Children’s Hospital, Sheffield, and Royal Marsden/St. George’s Hospital, London.
G.M. Vujanic and N.J. Sebire reviewed all renal tumor cases originally, as part of their Panel’s work. G.M. Vujanic then re-reviewed the cases included in the study together with M. Shiavo Lena, who identified the cases from the whole archive.
M. Schiavo Lena did the search of the literature, found and read the papers, and extracted the data we needed for the review.
G.M. Vujanic and M. Schiavo Lena prepared a first draft of the manuscript. It was then further discussed and improved in collaboration with N.J. Sebire. The final draft was approved by all three authors.
Compliance with ethical standards
All cases included in the present study were identified from the SIOP UK 2001 Trial and Study, which recruited patients in the UK, and for whose inclusion a full, informed consent has been obtained.
Conflict of interest
The authors declare that there is no conflict of interest.
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