Presence of viable germ cells in testicular regression syndrome remnants: Is routine excision indicated? A systematic review

There is no consensus in the literature about the necessity for excision of testicular remnants in the context of surgery for an impalpable testis and testicular regression syndrome (TRS). The incidence of germ cells (GCs) within these nubbins varies between 0 and 16% in previously published series. There is a hypothetical potential future malignancy risk, although there has been only one previously described isolated report of intratubular germ-cell neoplasia. Our aim was to ascertain an accurate incidence of GCs and seminiferous tubules (SNTs) within excised nubbins and hence guide evidence-based practice. The systematic review protocol was designed according to the PRISMA guidelines, and subsequently published by the PROSPERO database after review (CRD42013006034). The primary outcome measure was the incidence of GCs and the secondary outcome was the incidence of SNTs. The comprehensive systematic review included articles published between 1980 and 2016 in all the relevant databases using specific search parameters and terms. Strict inclusion and exclusion criteria were ultilised to identify articles relevant to the review questions. Twenty-nine paediatric studies with a total of 1455 specimens were included in the systematic review. The mean age of the patients undergoing nubbin resection was 33 months and the TRS specimen was more commonly excised from the left (68%). The incidence of SNTs was 10.7% (156/1455) and the incidence of GCs, 5.3% (77/1455). Histological analysis excluding the presence of either SNTs or GCs was consistent with TRS, fibrosis, calcification or haemosiderin deposits. There is limited evidence on subset analysis that GCs and SNTs may persist with increasing patient age. This systematic review has identified that 1 in 20 of resected testicular remnants has viable GCs and 1 in 10 has SNTs present. There is insufficiently strong evidence for the persistence of GCs and SNTs with time or future malignant potential. Intra-abdominal TRS specimens may contain more elements and, therefore, require excision, although this is based on limited evidence. However, there is no available strong evidence to determine that a TRS specimen requires routine excision in an inguinal or scrotal position.