Sacrococcygeal teratoma

Sacrococcygeal teratoma (SCT) is the most common congenital tumor in newborns, arising from the coccyx (tailbone) region at the base of the spine. It is a germ cell tumor composed of tissues derived from all three embryonic germ layers (ectoderm, mesoderm, and endoderm), meaning it can contain a variety of tissue types including skin, hair, teeth, bone, muscle, and neural tissue. SCT can range from predominantly external masses protruding from the sacrococcygeal area to predominantly internal (presacral) tumors, and is classified into four types (Altman classification) based on the ratio of external to internal components. The majority of cases are diagnosed prenatally by ultrasound or at birth. Most sacrococcygeal teratomas are benign (mature teratomas), particularly when diagnosed in the neonatal period. However, a proportion may be malignant (immature teratomas or contain yolk sac tumor elements), with the risk of malignancy increasing with age at diagnosis and with delayed surgical treatment. Key clinical features include a visible mass at the base of the spine, which can vary greatly in size. Large tumors diagnosed prenatally may cause complications including polyhydramnios, fetal hydrops due to high-output cardiac failure from tumor vascularity, and preterm delivery. Postnatally, symptoms may include constipation, urinary obstruction, and lower extremity weakness depending on the tumor's size and internal extent. The primary treatment for sacrococcygeal teratoma is complete surgical resection, including removal of the coccyx to reduce the risk of recurrence. For prenatally diagnosed cases with life-threatening complications such as fetal hydrops, fetal intervention may be considered, including tumor debulking or vascular ablation procedures. Malignant SCTs are treated with a combination of surgery and platinum-based chemotherapy. Long-term follow-up is essential, as recurrence can occur even after complete resection, and survivors may experience functional sequelae including bowel and bladder dysfunction. Serum alpha-fetoprotein (AFP) levels are monitored as a tumor marker for recurrence or malignant transformation. Overall prognosis is excellent for mature teratomas diagnosed and treated early, with survival rates exceeding 90% in neonates.

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