A sacrococcygeal teratoma is an extragonadal germ cell tumor arising in the sacrococcygeal region, composed of tissues foreign to the site of origin. It typically contains elements from all three embryonic germ layers, although monodermal variants can occur.
• Epidemiology: It is the most common tumor presenting in the newborn period. The incidence is estimated at 1 in 35,000 to 40,000 live births, rising to 1 in 10,000 to 14,000 when fetal cases are included.
• Age/Gender Predilection: There is a marked female predominance with a female-to-male ratio of 3:1 in isolated cases, which decreases to 1.5:1 in syndromic cases.
• Etiology / Types: The biological behavior ranges from mature benign lesions containing fully differentiated tissues to immature or frankly malignant tumors. Fetal and neonatal presentations are predominantly benign, while the risk of malignancy increases significantly with age at diagnosis. Morphologically, lesions may be purely cystic in 10–15% of cases, solid, or mixed cystic and solid.