The Irish Experience with Sacrococcygeal Teratomas: Are Type IV Lesions More Common than We Think?

Introduction Sacrococcygeal teratomas (SCTs) are rare tumors occurring in approximately 1 in 35,000 to 40,000 live births. The Altman classification is used to describe SCTs. There are four types, with type 1 predominantly external through to type IV which is a presacral, completely internal mass. As far as the authors are aware, this is the first study to focus on type IV SCT lesions. Materials and Methods Using ICD-10-AM (The International Statistical Classification of Diseases and Related Health Problems, Tenth Revision, Australian Modification) codes, we identified all patients in the Republic of Ireland with a diagnosis of SCT from 2004 to 2020. The following information was obtained for each patient: gender, time of diagnosis, clinical presentation, method of diagnosis, Altman classification, biomarkers, age at operation, surgical technique, pathology, recurrence, and age at most recent follow-up. Results There were 29 patients in total; 23 females (79%) and 6 males (21%). In total, 16 (55%) were diagnosed antenatally, 4 (14%) at less than 1 month, 4 (14%) less than 1 year, 3 (10%) age 2 to 4 years, and 2 (7%) were aged 5 to 12 years. In addition, 22 (76%) were mature teratomas, 2 (7%) immature teratomas, and 5 (17%) were malignant tumors. There were 6 (21%) type I lesions, 9 (30%) type II, 6 (21%) type III, and 8 (28%) type IV lesions. Conclusion In Altman's original 1974 study, type IV lesions were present in 10% of cases. As a result, this is the most frequently quoted figure. Type IV lesions were present in 28% of cases in our study. We propose that type IV lesions may be more common than the current literature suggests and consequently a higher index of suspicion of their presence should be entertained.