DrSreelekshmy
DrJayasree (Aims Neo)DrC Jayakumar
Twenty day old ba, term first child of NCM, born LSCS to a primi mother at term cried immediately after birth.
Ba was antenatally detected to have a heterogenous mass in the sacral region. Postnatal MRI showed a Heterogenous complex mass (3.6×3.2×4.2cm) sized involving coccyx and lower sacrum in midline and entering in left paramedian gluteal region containing fat, fluid, low signal intensity calcification and soft tissue components. Imaging possibility of sacro-coccygeal teratoma with possible intradural extension at this level and small presacral extension.
At admission Ba is active with stable vitals. Local examination revealed a 5x5cm hard mass in the left gluteal region, medially extending till midline, nontender, no erythema.
Systemic examination was within normal limits.
Excision of teratoma was under GA and noted to have a hard, lobulated 4x4cm irregular shaped lesion in the sacral region extending to the left of natal cleft extending deep just below coccyx.
No obvious intraspinal extension noted.
Lesion was dissected off the rectum, excised in whole and sent for histopathological examination. Post operative period was uneventful.
Histopathology showed skin and lobules of cartilage in the deep part, there is a cystic and solid lesion comprising epidermis lined cysts with appendages, intestinal epithelium lined cysts, ciliated respiratory epithelium lined cysts with smooth muscle in the wall. Seromucinous glands, lobules with Paneth cells along with nerve bundles, ganglion cells, brown and white fat and bony trabeculae enclosing marrow. Foci resembling gonadal tissue, Glomus coccygeum are seen. No immature or neuroectodermal elements seen. Morphologic features are suggestive of Mature cystic teratoma.
Discussion:
Sacrococcygeal teratoma (SCT) is a rare, often congenital tumor that arises from the area of the sacrum or coccyx, typically at the base of the spine. It is one of the most common congenital tumors found in neonates.
Incidence: higher in females (approximately 80-90% of cases are female). The reasons for this difference are not fully understood, but hormonal factors or sex-linked genetic factors may play a role in the increased risk in females.
Prevalance: approximately 1 in 35,000 to 40,000 live births.
Development of SCT involve a combination of embryological processes and genetic factors.
1. Embryological Origin and Teratogenesis
SCT is thought to arise from abnormal development during the embryonic period, specifically involving the primitive streak and the primitive notochord. The primitive streak is the structure in the embryo from which the mesoderm, ectoderm, and endoderm derive. The teratoma is believed to form when pluripotent cells (cells capable of developing into a variety of tissues) from the primitive streak are retained in the area of the coccyx. These cells then undergo abnormal differentiation into tissues of various origins, such as muscle, bone, hair, and even neural tissue.
The teratoma’s composition often includes tissues from all three germ layers—ectoderm, mesoderm, and endoderm—resulting in a mixed tumor that may include features such as hair, teeth, muscle, and even glandular tissue.
2. Clonal Growth and Genetic Factors
Several theories suggest that SCT may arise from clonal growth of these pluripotent cells, which continue to proliferate abnormally after embryonic development. Some genetic factors, such as mutations or changes in the expression of genes involved in cell differentiation and proliferation, may contribute to the formation and growth of the tumor. However, the exact molecular mechanisms and genetic mutations responsible for SCT are still under investigation.
There is some evidence that chromosomal abnormalities may play a role. For example, studies have shown that some SCTs are associated with chromosomal anomalies like trisomy 13, trisomy 18, or monosomy X. Additionally, abnormal gene expression related to cell cycle regulation, such as the overexpression of growth factors, may lead to tumor development.
3. Molecular Pathogenesis
Specific molecular markers such as TERT (telomerase reverse transcriptase) and KRAS mutations have been implicated in the growth of certain types of SCTs.
4. Immunological and Environmental Factors
These may include maternal infections, exposures to toxins, or conditions like diabetes during pregnancy, though these factors have not been conclusively proven to directly cause SCT.
Growth Patterns
External: The tumor is largely visible outside the body and is often detected prenatally via ultrasound.
Internal: The tumor grows internally into the pelvic or abdominal cavity, often making diagnosis more challenging until later in pregnancy or after birth.
Clinical Features
At Birth:
Visible mass: In the majority of cases, SCT presents as a visible mass near the coccyx or sacrum, which may be covered skin or ulcerated (which can lead to infection).
Complications:
Larger tumors can lead to:
Hydrops fetalis (fluid buildup around the fetus), which can cause fetal distress or preterm labor.
Distended abdomen or large mass visible at birth.
Heart failure due to large tumors causing increased venous return or compression of the inferior vena cava.
Postnatal Symptoms:
Failure to thrive or poor feeding.
Abdominal distension or a palpable mass in the sacral area.
If the tumor is large and extends into the abdomen, it can displace organs and cause issues like intestinal obstruction or urinary tract compression.
Associated Anomalies:
Spinal anomalies (such as sacral dysgenesis), although rare, can be associated with SCT.
Chromosomal abnormalities, including trisomy 13, trisomy 18, or monosomy X, may also occur, particularly in more severe cases.
Diagnosis:
Antenatal diagnosis is important for planning the management of both the pregnancy and delivery, as well as addressing potential complications associated with SCT.
Treatment:
largely depends on the size, location, and type of the tumor, as well as whether it has caused any complications in the fetus or neonate.
1. Antenatal Management:
Monitoring: Regular ultrasounds and fetal monitoring are conducted to assess the size of the tumor, fetal well-being, and any signs of complications such as hydrops fetalis or heart failure.
Steroids: In some cases, steroids may be given to the mother to help mature the fetus’ lungs, especially if there is concern about preterm delivery or if the tumor is causing significant fetal distress.
Fetal Surgery: In rare cases, fetal surgery may be performed to drain fluid or remove part of the tumor in order to improve the outcome. This is usually considered when the fetus is at risk of severe complications that cannot be managed with other interventions.
2. Postnatal Management:
Surgical Removal:
The mainstay of treatment for SCT is surgical resection. The tumor is typically removed soon after birth to avoid complications such as infection, bleeding, or compression of surrounding structures.
The timing of surgery depends on the size and extent of the tumor. In cases where the tumor is large, surgery may be delayed to allow the infant to stabilize.
For smaller tumors, surgery may be done within the first few days or weeks of life.
Surgical Approach:
Excision is typically performed through a posterior approach, where the tumor is carefully dissected from surrounding tissue.
3. Long-Term Follow-Up:
After the tumor is removed, regular follow-up is required to monitor for potential recurrence, as SCT can recur in rare cases.
Long-term follow-up may also be necessary for evaluating any associated neurological or musculoskeletal complications that could result from a large tumor or surgical intervention.
Prognosis:
largely depends on the size of the tumor, its location, and whether it has caused any complications, such as fetal hydrops or neurological impairment.
Benign tumors typically have an excellent prognosis if completely resected, with survival rates close to 100%.
Prognosis can be more guarded in cases where the tumor is malignant, large, or associated with severe complications (e.g., fetal hydrops or heart failure).
The presence of associated anomalies, such as chromosomal abnormalities or spinal defects, can affect long-term outcomes and may require additional interventions.