Sacrococcygeal teratoma
Encyclopedia
Sacrococcygeal teratoma (SCT) is a teratoma
(a kind of tumor) located at the base of the coccyx
(tailbone). It is thought to be a derivative of the primitive streak
.
in newborn humans. Most SCTs are found in babies and children, but SCTs have been reported in adults and the increasingly routine use of prenatal ultrasound exams has dramatically increased the number of diagnosed SCTs presenting in fetuses. Like other teratomas, an SCT can grow very large. Unlike other teratomas, an SCT sometimes grows larger than the rest of the fetus.
Sacrococcygeal teratomas are the most common type of germ cell tumor
s (both benign
and malignant
) diagnosed in neonates, infants, and children younger than 4 years. SCTs occur more often in girls than in boys; ratios of 3:1 to 4:1 have been reported.
Historically, sacrococcygeal teratomas present in 2 clinical patterns related to the child’s age, tumor location, and likelihood of tumor malignancy. With the advent of routine prenatal ultrasound examinations, a third clinical pattern is emerging.
At birth
, the usual presentation is a visible lump or mass under the skin at the top of the buttocks crease. If not visible, it can sometimes be felt; gently prodded, it feels somewhat like a hardboiled egg. A small SCT, if it is entirely inside the body, may not present for years, until it grows large enough to cause pain, constipation and other symptoms of a large mass inside the pelvis
, or until it begins to extend out of the pelvis. Even a relatively large SCT may be missed, if it is internal, because the bony pelvis
conceals and protects it. Mediastinal tumors, including teratomas, are similarly concealed and protected by the rib cage
.
Some SCTs are discovered when a child begins to talk at about age 2 years and complains of their bottom hurting or feeling "poopy" when they ride in a car seat.
Other tumors can occur in the sacrococcygeal and/or presacral regions and hence must be ruled out to obtain a differential diagnosis
. These include extraspinal ependymoma
, ependymoblastoma, neuroblastoma
and rhabdomyosarcoma
.
Smaller SCTs with an external component, seen in prenatal ultrasounds or at birth, often are mistaken for spina bifida
. Cystic SCT and terminal myelocystocele are especially difficult to distinguish; for more accurate diagnosis, MRI has been recommended.
; a large SCT may require an additional approach through the abdomen
. Resection should include the coccyx and may also include portions of the sacrum
. The surgery should include reattachment of the small muscles and ligaments formerly attached to the coccyx, in effect reconstructing the posterior perineum. If not, there is an increased risk of perineal hernia
later in life.
SCTs are classified morphologically according to their relative extent outside and inside the body:
The Altman type is significant in the contexts of management of labor and delivery, surgical approach, and complications of SCT. Serial ultrasound and MRI monitoring of SCTs in fetuses in utero
has demonstrated that the Altman type can change over time. As the tumor grows, it can push between other organs and through the perineum to the body surface where the tumor appears as a bulge covered only by skin. Sometimes, the tumor bulge later slips back inside the perineum.
Like all teratoma
s, a sacrococcygeal teratoma has the potential to be malignant
, and the standard of care requires long-term followup by an oncologist. For a detailed account of SCT diagnosis and treatment along with over 100 notes from family members of children diagnosed with SCT, consult the following site: www.sctsurvivor.com.
The charity www.sctcharity.org.uk was formed to raise awareness of Saccroccygeal Teratoma, providing a support network to ensure parents have access to relevant information and contacts pre and post birth.
prior to any treatment. An often used decision tree
is as follows:
Emergent problems include maternal mirror syndrome
, polyhydramnios
, and preterm labor. Poor management decisions, including interventions that are either premature or delayed, can have dire consequences. A very small retrospective study of 9 babies with SCTs greater than 10 cm diameter reported slightly higher survivorship in babies remaining in utero slightly longer.
In many cases, a fetus with a small SCT (under 5 or 10 cm) may be delivered vaginally. Prior to the advent of prenatal detection and hence scheduled C-section, 90% of babies diagnosed with SCT were born full term.
, some surgeons prefer not to remove the coccyx of adult survivors of SCT. There are case reports of good outcomes.
. Maternal complications of delivery may include a Cesarean section or, alternatively, a vaginal delivery with mechanical dystocia
.
Complications of the mass effect of a teratoma in general are addressed on the teratoma
page. Complications of the mass effect of a large SCT may include hip dysplasia
, bowel obstruction
, urinary obstruction, hydronephrosis
and hydrops fetalis
. Even a small SCT can produce complications of mass effect, if it is presacral (Altman Type IV). In the fetus, severe hydronephrosis may contribute to inadequate lung development. Also in the fetus and newborn, the anus
may be imperforate
.
Later complications of the mass effect and/or surgery may include neurogenic bladder
, other forms of urinary incontinence
, fecal incontinence
, and other chronic problems resulting from accidental damage to or sacrifice of nerves and muscles within the pelvis. Removal of the coccyx
may include additional complications. In one review of 25 patients, however, the most frequent complication was an unsatisfactory appearance of the surgical scar.
Complications of not removing the coccyx may include both recurrence of the teratoma and metastatic cancer
. Late malignancies usually involve incomplete excision of the coccyx and are adenocarcinoma
.
Although functional disability in survivors is common, a small comparative study found a nonsignificant difference between SCT survivors and a matched control group.
In rare cases, pelvic scarring may necessitate that a pregnant woman
who is a SCT survivor deliver her baby by Cesarean section.
Teratoma
A teratoma is an encapsulated tumor with tissue or organ components resembling normal derivatives of all three germ layers. There are rare occasions when not all three germ layers are identifiable...
(a kind of tumor) located at the base of the coccyx
Coccyx
The coccyx , commonly referred to as the tailbone, is the final segment of the vertebral column. Comprising three to five separate or fused vertebrae below the sacrum, it is attached to the sacrum by a fibrocartilaginous joint, the sacrococcygeal symphysis, which permits limited movement between...
(tailbone). It is thought to be a derivative of the primitive streak
Primitive streak
The primitive streak is a structure that forms during the early stages of avian, reptilian and mammalian embryonic development.-Introduction:...
.
Natural history
SCT is seen in 1 in every 35,000 live births, and is the most common tumor presentingPresenting
In medicine, the term presenting means not only present, but seen. For example, at birth most babies present head first and their presenting part is their head....
in newborn humans. Most SCTs are found in babies and children, but SCTs have been reported in adults and the increasingly routine use of prenatal ultrasound exams has dramatically increased the number of diagnosed SCTs presenting in fetuses. Like other teratomas, an SCT can grow very large. Unlike other teratomas, an SCT sometimes grows larger than the rest of the fetus.
Sacrococcygeal teratomas are the most common type of germ cell tumor
Germ cell tumor
A germ cell tumor is a neoplasm derived from germ cells. Germ cell tumors can be cancerous or non-cancerous tumors. Germ cells normally occur inside the gonads...
s (both benign
Benign
A benign tumor is a tumor that lacks the ability to metastasize. Common examples of benign tumors include moles and uterine fibroids.The term "benign" implies a mild and nonprogressive disease. Indeed, many kinds of benign tumors are harmless to human health...
and malignant
Malignant
Malignancy is the tendency of a medical condition, especially tumors, to become progressively worse and to potentially result in death. Malignancy in cancers is characterized by anaplasia, invasiveness, and metastasis...
) diagnosed in neonates, infants, and children younger than 4 years. SCTs occur more often in girls than in boys; ratios of 3:1 to 4:1 have been reported.
Historically, sacrococcygeal teratomas present in 2 clinical patterns related to the child’s age, tumor location, and likelihood of tumor malignancy. With the advent of routine prenatal ultrasound examinations, a third clinical pattern is emerging.
- Fetal tumors present during prenatal ultrasound exams, with or without maternal symptoms. SCTs found during routine exams tend to be small and partly or entirely external. The internal SCTs are not easily seen via ultrasound, unless they are large enough to reveal their presence by the abnormal position of the fetal urinary bladderUrinary bladderThe urinary bladder is the organ that collects urine excreted by the kidneys before disposal by urination. A hollow muscular, and distensible organ, the bladder sits on the pelvic floor...
and other organs, but large fetal SCTs frequently produce maternal complications which necessitate non-routine, investigative ultrasounds.
- Neonatal tumors present at birth protruding from the sacral site and are usually mature or immature teratomas.
- Among infants and young children, the tumor presents as a palpable mass in the sacropelvic region compressing the bladder or rectum. These pelvic tumors have a greater likelihood of being malignant. An early survey found that the rate of tumor malignancy was 48% for girls and 67% for boys older than 2 months at the time of sacrococcygeal tumor diagnosis, compared with a malignant tumorCancerCancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
incidence of 7% for girls and 10% for boys younger than 2 months at the time of diagnosis. The pelvic site of the primary tumorPrimary tumorA primary tumor is a tumor growing at the anatomical site where tumor progression began and proceeded to yield a cancerous mass....
has been reported to be an adverse prognostic factor, most likely caused by a higher rate of incomplete resection.
- In older children and adults, the tumor may be mistaken for a pilonidal sinus, or it may be found during a rectal exam or other evaluation.
Diagnosis
During prenatal ultrasound, an SCT having an external component may appear as a fluid-filled cyst or a solid mass sticking out from the fetus' body. Fetal SCTs that are entirely internal may be undetected if they are small; detection (or at least suspicion) is possible when the fetal bladder is seen in an abnormal position, due to the SCT pushing other organs out of place.At birth
Birth
Birth is the act or process of bearing or bringing forth offspring. The offspring is brought forth from the mother. The time of human birth is defined as the time at which the fetus comes out of the mother's womb into the world...
, the usual presentation is a visible lump or mass under the skin at the top of the buttocks crease. If not visible, it can sometimes be felt; gently prodded, it feels somewhat like a hardboiled egg. A small SCT, if it is entirely inside the body, may not present for years, until it grows large enough to cause pain, constipation and other symptoms of a large mass inside the pelvis
Pelvis
In human anatomy, the pelvis is the lower part of the trunk, between the abdomen and the lower limbs .The pelvis includes several structures:...
, or until it begins to extend out of the pelvis. Even a relatively large SCT may be missed, if it is internal, because the bony pelvis
Pelvis
In human anatomy, the pelvis is the lower part of the trunk, between the abdomen and the lower limbs .The pelvis includes several structures:...
conceals and protects it. Mediastinal tumors, including teratomas, are similarly concealed and protected by the rib cage
Rib cage
The rib cage is an arrangement of bones in the thorax of animals. It is formed by the vertebral column, ribs and sternum and encloses the heart and lungs....
.
Some SCTs are discovered when a child begins to talk at about age 2 years and complains of their bottom hurting or feeling "poopy" when they ride in a car seat.
Other tumors can occur in the sacrococcygeal and/or presacral regions and hence must be ruled out to obtain a differential diagnosis
Differential diagnosis
A differential diagnosis is a systematic diagnostic method used to identify the presence of an entity where multiple alternatives are possible , and may also refer to any of the included candidate alternatives A differential diagnosis (sometimes abbreviated DDx, ddx, DD, D/Dx, or ΔΔ) is a...
. These include extraspinal ependymoma
Ependymoma
Ependymoma is a tumor that arises from the ependyma, a tissue of the central nervous system. Usually, in pediatric cases the location is intracranial, while in adults it is spinal. The common location of intracranial ependymoma is the fourth ventricle...
, ependymoblastoma, neuroblastoma
Neuroblastoma
Neuroblastoma is the most common extracranial solid cancer in childhood and the most common cancer in infancy, with an annual incidence of about 650 cases per year in the US , and 100 cases per year in the UK . Close to 50 percent of neuroblastoma cases occur in children younger than two years old...
and rhabdomyosarcoma
Rhabdomyosarcoma
A rhabdomyosarcoma is a type of cancer, specifically a sarcoma , in which the cancer cells are thought to arise from skeletal muscle progenitors. It can also be found attached to muscle tissue, wrapped around intestines, or in any anatomic location...
.
Smaller SCTs with an external component, seen in prenatal ultrasounds or at birth, often are mistaken for spina bifida
Spina bifida
Spina bifida is a developmental congenital disorder caused by the incomplete closing of the embryonic neural tube. Some vertebrae overlying the spinal cord are not fully formed and remain unfused and open. If the opening is large enough, this allows a portion of the spinal cord to protrude through...
. Cystic SCT and terminal myelocystocele are especially difficult to distinguish; for more accurate diagnosis, MRI has been recommended.
Treatment
The preferred first treatment for SCT is complete surgical removal (i.e., complete resection). The preferred approach to a small SCT is through the perineumPerineum
In human anatomy, the perineum is a region of the body including the perineal body and surrounding structures...
; a large SCT may require an additional approach through the abdomen
Abdomen
In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity...
. Resection should include the coccyx and may also include portions of the sacrum
Sacrum
In vertebrate anatomy the sacrum is a large, triangular bone at the base of the spine and at the upper and back part of the pelvic cavity, where it is inserted like a wedge between the two hip bones. Its upper part connects with the last lumbar vertebra, and bottom part with the coccyx...
. The surgery should include reattachment of the small muscles and ligaments formerly attached to the coccyx, in effect reconstructing the posterior perineum. If not, there is an increased risk of perineal hernia
Perineal hernia
Perineal hernia is a hernia involving the perineum . The hernia may contain fluid, fat, any part of the intestine, the rectum, or the bladder. It is known to occur in humans, dogs, and other mammals, and often appears as a sudden swelling to one side of the anus.A common cause of perineal hernia...
later in life.
SCTs are classified morphologically according to their relative extent outside and inside the body:
- Altman type I — entirely outside, sometimes attached to the body only by a narrow stalk
- Altman type II — mostly outside
- Altman type III — mostly inside
- Altman type IV — entirely inside; this is also known as a presacral teratoma or retrorectal teratoma
The Altman type is significant in the contexts of management of labor and delivery, surgical approach, and complications of SCT. Serial ultrasound and MRI monitoring of SCTs in fetuses in utero
In utero
In utero is a Latin term literally meaning "in the womb". In biology, the phrase describes the state of an embryo or fetus. In legal contexts, the phrase is used to refer to unborn children. Under common law, unborn children are still considered to exist for property transfer purposes.-See also:*...
has demonstrated that the Altman type can change over time. As the tumor grows, it can push between other organs and through the perineum to the body surface where the tumor appears as a bulge covered only by skin. Sometimes, the tumor bulge later slips back inside the perineum.
Like all teratoma
Teratoma
A teratoma is an encapsulated tumor with tissue or organ components resembling normal derivatives of all three germ layers. There are rare occasions when not all three germ layers are identifiable...
s, a sacrococcygeal teratoma has the potential to be malignant
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
, and the standard of care requires long-term followup by an oncologist. For a detailed account of SCT diagnosis and treatment along with over 100 notes from family members of children diagnosed with SCT, consult the following site: www.sctsurvivor.com.
The charity www.sctcharity.org.uk was formed to raise awareness of Saccroccygeal Teratoma, providing a support network to ensure parents have access to relevant information and contacts pre and post birth.
Management of fetal SCTs
Management of most fetal SCTs involves watchful waitingWatchful waiting
Watchful waiting is an approach to a medical problem in which time is allowed to pass before medical intervention or therapy is used. During this time, repeated testing may be performed....
prior to any treatment. An often used decision tree
Decision tree
A decision tree is a decision support tool that uses a tree-like graph or model of decisions and their possible consequences, including chance event outcomes, resource costs, and utility. It is one way to display an algorithm. Decision trees are commonly used in operations research, specifically...
is as follows:
- Perform detailed ultrasound exam including fetal echocardiogram and Doppler flow analysisData-flow analysisData-flow analysis is a technique for gathering information about the possible set of values calculated at various points in a computer program. A program's control flow graph is used to determine those parts of a program to which a particular value assigned to a variable might propagate. The...
- If fetal high output failure, placentomegaly, or hydropsHydrops-Medicine:* In general, hydrops is another name for edema.** Endolymphatic hydrops - a pathological feature present in Ménière's disease.** Hydrops fetalis is edema in a fetus.-Zoology:* Hydrops, a colubrid snake genus....
- If fetus not mature, perform pregnancy termination or fetal interventionFetal interventionFetal intervention involves in utero surgical treatment of a fetus. Procedures include open fetal surgery, the most invasive, and the less invasive fetendo and fetal image-guided surgery.Fetal intervention is relatively new...
- Else fetus mature, perform emergency Cesarean section
- If fetus not mature, perform pregnancy termination or fetal intervention
- Else no emergent problems, perform serial non-stress tests and ultrasound biophysical profileBiophysical profileA biophysical profile is a prenatal ultrasound evaluation of fetal well-being, involving a scoring system. It is often done when a non-stress test is non reactive, or for other obstetrical indications.-The test:...
s and plan delivery, as follows- If emergent problems develop, return to top of decision tree
- Else if SCT over 5–10 cm or polyhydramniosPolyhydramniosPolyhydramnios is a medical condition describing an excess of amniotic fluid in the amniotic sac. It is seen in 0.2 to 1.6% of pregnancies,,...
, perform early (37 weeks gestation) elective CesareanCaesarean delivery on maternal requestCaesarean delivery on maternal request is a medically unnecessary caesarean section, where the conduct of a childbirth via a caesarean section is requested by the pregnant patient...
section - Else SCT small and no complications, permit term spontaneous vaginal deliverySpontaneous vaginal deliveryA vaginal delivery is the birth of offspring in mammals through the vagina. It is the natural method of birth for all mammals except monotremes, which lay eggs into the external environment...
- If fetal high output failure, placentomegaly, or hydrops
Emergent problems include maternal mirror syndrome
Mirror syndrome
Mirror syndrome or triple oedema or Ballantyne syndrome is a rare disorder affecting pregnant women. It describes the unusual association of fetaland placental hydrops with maternal preeclampsia....
, polyhydramnios
Polyhydramnios
Polyhydramnios is a medical condition describing an excess of amniotic fluid in the amniotic sac. It is seen in 0.2 to 1.6% of pregnancies,,...
, and preterm labor. Poor management decisions, including interventions that are either premature or delayed, can have dire consequences. A very small retrospective study of 9 babies with SCTs greater than 10 cm diameter reported slightly higher survivorship in babies remaining in utero slightly longer.
In many cases, a fetus with a small SCT (under 5 or 10 cm) may be delivered vaginally. Prior to the advent of prenatal detection and hence scheduled C-section, 90% of babies diagnosed with SCT were born full term.
Management of adult SCTs
SCTs are very rare in adults, and as a rule these tumors are benign and have extremely low potential for malignancy. This estimation of potential is based on the idea that because the tumor existed for decades prior to diagnosis, without becoming malignant, it has little or no potential to ever become malignant. For this reason, and because coccygectomy in adults has greater risks than in babiesCoccygectomy
Coccygectomy is a surgical procedure during which the coccyx, is removed. It can be performed for many reasons for instance in patients with coccyx pain , however it is typically reserved for patients with malignant cancer or for patients whose tailbone pain has failed to respond to nonsurgical...
, some surgeons prefer not to remove the coccyx of adult survivors of SCT. There are case reports of good outcomes.
Complications
Maternal complications of pregnancy may include mirror syndromeMirror syndrome
Mirror syndrome or triple oedema or Ballantyne syndrome is a rare disorder affecting pregnant women. It describes the unusual association of fetaland placental hydrops with maternal preeclampsia....
. Maternal complications of delivery may include a Cesarean section or, alternatively, a vaginal delivery with mechanical dystocia
Dystocia
Dystocia is an abnormal or difficult childbirth or labour. Approximately one fifth of human labours have dystocia.Dystocia may arise due to incoordinate uterine activity, abnormal fetal lie or presentation, absolute or relative cephalopelvic disproportion, or a massive fetal tumor such as a...
.
Complications of the mass effect of a teratoma in general are addressed on the teratoma
Teratoma
A teratoma is an encapsulated tumor with tissue or organ components resembling normal derivatives of all three germ layers. There are rare occasions when not all three germ layers are identifiable...
page. Complications of the mass effect of a large SCT may include hip dysplasia
Hip dysplasia (human)
Hip dysplasia, developmental dysplasia of the hip or congenital dysplasia of the hip is a congenital or acquired deformation or misalignment of the hip joint.-Terminology:...
, bowel obstruction
Bowel obstruction
Bowel obstruction is a mechanical or functional obstruction of the intestines, preventing the normal transit of the products of digestion. It can occur at any level distal to the duodenum of the small intestine and is a medical emergency...
, urinary obstruction, hydronephrosis
Hydronephrosis
Hydronephrosis is distension and dilation of the renal pelvis calyces, usually caused by obstruction of the free flow of urine from the kidney, leading to progressive atrophy of the kidney...
and hydrops fetalis
Hydrops fetalis
Hydrops fetalis is a condition in the fetus characterized by an accumulation of fluid, or edema, in at least two fetal compartments. By comparison, hydrops allantois or hydrops amnion are an accumulation of excessive fluid in the allantoic or amniotic space respectively.-Presentation:Locations can...
. Even a small SCT can produce complications of mass effect, if it is presacral (Altman Type IV). In the fetus, severe hydronephrosis may contribute to inadequate lung development. Also in the fetus and newborn, the anus
Anus
The anus is an opening at the opposite end of an animal's digestive tract from the mouth. Its function is to control the expulsion of feces, unwanted semi-solid matter produced during digestion, which, depending on the type of animal, may be one or more of: matter which the animal cannot digest,...
may be imperforate
Imperforate anus
An imperforate anus or anal atresia is a birth defect in which the rectum is malformed. Its cause is unknown.-Features:There are several forms of imperforate anus:* A low lesion, in which the colon remains close to the skin...
.
Later complications of the mass effect and/or surgery may include neurogenic bladder
Neurogenic bladder
Neurogenic bladder refers to dysfunction of the urinary bladder due to disease of the central nervous system or peripheral nerves involved in the control of micturition .-Causes:...
, other forms of urinary incontinence
Urinary incontinence
Urinary incontinence is any involuntary leakage of urine. It is a common and distressing problem, which may have a profound impact on quality of life. Urinary incontinence almost always results from an underlying treatable medical condition but is under-reported to medical practitioners...
, fecal incontinence
Fecal incontinence
Fecal incontinence is the loss of regular control of the bowels. Involuntary excretion and leaking are common occurrences for those affected. Subjects relating to defecation are often socially unacceptable, thus those affected may be beset by feelings of shame and humiliation...
, and other chronic problems resulting from accidental damage to or sacrifice of nerves and muscles within the pelvis. Removal of the coccyx
Coccygectomy
Coccygectomy is a surgical procedure during which the coccyx, is removed. It can be performed for many reasons for instance in patients with coccyx pain , however it is typically reserved for patients with malignant cancer or for patients whose tailbone pain has failed to respond to nonsurgical...
may include additional complications. In one review of 25 patients, however, the most frequent complication was an unsatisfactory appearance of the surgical scar.
Late effects
Late effects are of two kinds: consequences of the tumor itself, and consequences of surgery and other treatments for the tumor.Complications of not removing the coccyx may include both recurrence of the teratoma and metastatic cancer
Metastasis
Metastasis, or metastatic disease , is the spread of a disease from one organ or part to another non-adjacent organ or part. It was previously thought that only malignant tumor cells and infections have the capacity to metastasize; however, this is being reconsidered due to new research...
. Late malignancies usually involve incomplete excision of the coccyx and are adenocarcinoma
Adenocarcinoma
Adenocarcinoma is a cancer of an epithelium that originates in glandular tissue. Epithelial tissue includes, but is not limited to, the surface layer of skin, glands and a variety of other tissue that lines the cavities and organs of the body. Epithelium can be derived embryologically from...
.
Although functional disability in survivors is common, a small comparative study found a nonsignificant difference between SCT survivors and a matched control group.
In rare cases, pelvic scarring may necessitate that a pregnant woman
Pregnancy
Pregnancy refers to the fertilization and development of one or more offspring, known as a fetus or embryo, in a woman's uterus. In a pregnancy, there can be multiple gestations, as in the case of twins or triplets...
who is a SCT survivor deliver her baby by Cesarean section.