Sacrococcygeal teratoma

Sacro-coccygeal teratoma (SCT) refers to a teratoma arising in the sacro-coccygeal region. The coccyx is almost always involved 6.

Demographics and clinical presentation

It is the commonest congenital tumour in the fetus 11 and neonate 3. The incidence is estimated at ~1:35000-40000. There is recognised female predilection with a  M:F ratio of 1:4. Sacrococcygeal region is the commonest location for non CNS teratomas.


They are thought to arise from totipotent cells from the node of Hensen 1,3 at the anterior aspect of the coccyx by about the 2nd to 3rd weeks of gestation. There are most often mixed solid/cystic, although purely cystic types can occur in ~15% of cases.

The tumour is composed of the all three germ cells (i.e. ectoderm, mesoderm and endoderm)

  • most cases tend to be sporadic 12

Can have elevated levels of:

  • alpha feto protein (AFP)
  • beta HCG

A pathology-based classification is as:

  • benign (mature): much more common, comprising ≈60-70%
  • malignant (immature)

A location based classification system according to the American Academy of Pediatric Surgery Section Survey is:

  • type I: developing only outside the fetus (can have small pre-sacral component) ; accounts for the majority of cases, 47% 12
  • type II: extra-fetal with intra-pelvic pre-sacral extension
  • type III: extra-fetal with abdomino-pelvic extension
  • type IV: tumour developing completely in the fetal pelvis

Radiographic features

Plain film
  • may show a large mass projecting from the lower pelvic region or within the abdominopelvic cavity
  • may show calcification

Not part of routine investigation. Identifies bone, fat and cystic components. Calcification may again be seen.


Mature types tend to be more cystic which show as anechoic components. Solid types (which are much rarer) often show an echogenic mass within the pelvis.

The correlation between sonographic appearances and malignant components are thought to be poor 7.

Colour Doppler interrogation in some tumours may show marked hypervascularity with arterio-venous (AV) shunting.


Superior to ultrasound especially in assessment of the following areas 2:

  • colonic displacement
  • ureteric dilatation
  • associated hip dislocation
  • intraspinal extension
  • vaginal dilatation
  • metastatic assessment in malignant lesions

Signal characteristics can significantly vary depending on the constituent of the teratoma 1.

  • T1: fat components appear high signal, calcific/bony components low signal
  • T2: fluid (cystic) components appear high signal, calcific bony components low signal
  • T2* GRE: magnetic susceptibility artifact because of calcifications
  • T1 C+ (Gd): enhancing solid components


Treatment and prognosis

An SCT can be benign or malignant depending on whether mature or immature. The majority however tend to be benign (~80% 11). Those presenting in older infants tend to have a higher malignant potential which those presenting in utero have poor prognosis due to complications. Malignant change may be also commoner in males. Treatment is with surgical excision inclusive of coccygectomy with additional chemotherapy for malignant tumours 5.

Differential diagnosis

General imaging differential considerations include:

For type IV lesions also consider:

Share Article

Article Information

rID: 8307
Synonyms or Alternate Spellings:
  • Sacro-coccygeal teratoma
  • Sacro-coccygeal teratoma (SCT)
  • Sacro-coccygeal teratoma (SCGT)
  • SCGT
  • Sacrococcygeal teratomas
  • Sacro-coccygeal teratomas

Support Radiopaedia to see fewer ads

  • Drag
    Figure 1: gross pathology
    Drag here to reorder.
  • Drag
    Sacrococcygeal te...
    Case 1: probable type III
    Drag here to reorder.
  • Drag
    Tertatoma AXR
    Case 2: probable type IV
    Drag here to reorder.
  • Drag
    Multicystic mass ...
    Case 3
    Drag here to reorder.
  • Drag
    Case 4
    Drag here to reorder.
  • Drag
    Case 5
    Drag here to reorder.
  • Drag
    Case 6
    Drag here to reorder.
  • Updating… Please wait.

    Alert accept

    Error Unable to process the form. Check for errors and try again.

    Alert accept Thank you for updating your details.