Keywords
Neuroepithelium - sacrococcygeal teratoma - Totipotential cell
Introduction
Teratomas are composed of tissues derived from ectoderm, mesoderm, and endoderm. Sacrococcygeal
teratomas are developed from the totipotential cells of primitive knot which is a
remnant of the primitive streak in the coccygeal region.[1] With the incidence of 1/35000–1/40000 live birth, sacrococcygeal teratoma is considered
as the most common germ cell tumor in the neonatal period and infancy.[2] Sacrococcygeal teratoma shows female preponderance with male to female ratio 1:4.[3]
Clinical presentation varies depending on the age of the patient and location of the
tumor. In the neonatal period, tumor presents as exophytic mass at the sacral region
with occasional surface ulceration and hemorrhage, but younger child presents with
mass effect due to its enormous size and proximity to intra-abdominal organs.[4] Fetal tumors are diagnosed by prenatal ultrasound. Association with other congenital
anomaly such as myelomeningocele and vertebral malformation were reported.[5]
As per as the histology is concerned, sacrococcygeal teratomas are classified into
mature, immature and malignant category.[6] Biological behaviors are affected by age and sex. Mature teratomas are common in
neonates.[7]
Clinical and pathological variables of cases of sacrococcygeal teratoma were evaluated
in our study.
Materials and Methods
A retrospective, observational study was conducted in the Department of Pathology
in collaboration with the Department of Pediatric Surgery from February 2009 to January
2014. A total 13 cases of sacrococcygeal teratoma were included in the study. The
records of these patients with pediatric sacrococcygeal teratoma were reviewed for
age, sex distribution, clinical presentation, preoperative investigation, mode of
treatment, and follow-up. Pre-operative hematological and radiological evaluation
were noted in all cases.
Depending on the radiological findings, the extent of the tumors was analyzed and
categorized according to the American Academy of Pediatrics' surgical section classification
which includes four categories:
-
Type I: Predominantly external with minimal presacral component;
-
Type II: Present externally but with significant intrapelvic extension
-
Type III: Apparent externally but predominantly a pelvic mass extending into the abdomen
-
Type IV: Presacral with no external presentation.[8]
Both size and appearance of the tumors were recorded thoroughly. Depending on the
size, tumors were classified into small (2–5 cm diameter); moderate (5–10 cm diameter)
and large (>10 cm diameter) tumors. Hematoxylin and eosin stained slides were reviewed
in each case, and additional sections were from taken from paraffin block if needed.
An average 12 slides were examined in each case. Depending on histological findings,
tumors were classified broadly into mature, immature, and malignant tumors. Tumor
showing differentiated tissues and tumor having immature neuroepithelium were considered
to be mature and immature teratoma accordingly. Malignant tumors showed yolk sac tumor,
choriocarcinoma, or embryonal carcinoma along with differentiated tissues.[9]
Histological grading was done:
-
Grade 0: Tumor shows only mature tissue
-
Grade 1: Tumor shows rare foci of immature tissue <1 lpf/slide
-
Grade 2: Tumor shows moderate quantities of immature tissues, 1–3 lpf/slide
-
Grade 3: Tumor shows large quantities of immature tissue. >3 lpf/slide; with or without
malignant yolk sac elements.
Result
In the present study, a total of 13 cases diagnosed as congenital sacrococcygeal teratoma
were evaluated. The tumors presenting to us were mainly in the age group> 2 months,
with 10 out of 13 cases presenting in that age group. There were 9 female and 4 male
children. Gender incidence showed female preponderance with male: female ratio of
1:2.
The most common clinical presentation of sacrococcygeal teratoma in our study was
sacrococcygeal mass. All the cases of mature teratoma presented with a prominent mass
at sacrococcyx. 2 cases showed associated malformations (anorectal malformations).
According to the American Academy of Pediatrics (Altman's) classification, 23% of
cases were Type I, 31% of cases patients Type II, 31% of cases Type III and 15% were
for Type IV. The significant presacral component was noted in all malignant tumors.
Majority of cases on histopathological evaluation were documented as mature teratoma,
about 53.4% (7/13) followed by immature teratoma with 30.8% (4/13). Grossly, mature
teratoma was predominantly cystic (75%), whereas the remaining 25% were solid and
cystic. The immature teratoma was predominantly solid. Immature teratoma showed immature
neuroepithelial tissue in the form of neuroepithelial rosette. Two cases of malignancy
were reported in our study. Malignant yolk sac component was noted in both cases [Table 1].
Table 1
Histopathological diagnosis and grades of sacrococcygeal teratomas
|
Tumor type
|
Tumor grade
|
Number of cases
|
|
Mature
|
0
|
7
|
|
Immature
|
1
|
1
|
|
2
|
3
|
|
Malignant
|
3
|
2
|
|
Total
|
|
13
|
Mature sacrococcygeal teratoma showed the components derived from all the three germ
cell layers with complete differentiation. Ectodermal and endoderm derived tissues
were seen in all the cases of mature teratoma. Neural elements, glial tissue, and
choroid plexus were seen in 69.2%. Mesodermal elements such as adipose tissue, cartilage,
smooth, and skeletal muscle were noted. Organoid elements such as pancreatic and salivary
gland tissue in 15.4% [Table 2].
Table 2
Components of sacrococcygeal teratomas
|
Component
|
Total cases it is present (%)
|
|
CNS – Central nervous system
|
|
Ectodermal elements
|
13 (100)
|
|
Endodermal elements
|
13 (100)
|
|
Neural and CNS elements
|
9 (69.2)
|
|
Mesodermal elements
|
8 (61.5)
|
|
Organoid elements
|
2 (15.4)
|
Discussion
Sacrococcygeal teratoma at birth usually presents as a visible mass in the sacrococcygeal
region. Most of the neonates do not have any symptoms. Some may have cardiac failure,
disseminated intravascular coagulation, and rupture or bleeding within the tumor.
Those neonates having lesions with an intrapelvic component may present with urinary
obstruction. Children present with constipation, urinary retention, an abdominal mass
or symptoms of malignancy, like failure to thrive.[2] The present study mainly had neonates who presented with a mass at sacrococcyx.
The older children presented with mass, pain, and constipation.
The grading of sacrococcygeal teratoma is done according to the presence of immature
tissues. Grading of sacrococcygeal teratoma is done similar to the grading of an ovarian
teratoma.[6] According to this grading, the cases are classified into Grade 0, 1, 2 and 3. Grading
of sacrococcygeal teratoma does not correlate directly with prognosis, unlike that
of ovarian teratoma where grading has direct correlation with prognosis.[6]
In our study, the most common age of presentation was above 2 months of age. The male:
female ratio was 1:2, indicating female preponderance, as in other studies.[6],[8],[10],[11],[12]
Clinical manifestations of sacrococcygeal teratoma in our series included sacrococcygeal
mass in the majority of cases. Immature teratoma presented with a visible to ill-defined
mass at sacrococcyx. Our findings were similar to other studies.[6],[8],[13] In ours study, mass with congenital anomalies seen in 15%. This was 25% in a study
by Billman et al. Children <2 month age have a better prognosis. Malignant risk rises with age (Herman
et al., 2002). Rescorla et al. and Gabra et al. reported that mostly, children> 1 year age had malignant tumors.[3] In our study, 16% were malignant and they all presented after 1 month. In our study,
the incidence of Altman's types II and III were maximum. Amel Hashish et al. studied (Type I >Type II) in their study.[14]
A study by Bilik et al. reported that grossly 40% of the sacrococcygeal teratoma were solid, 20% were cystic,
and 40% were mixed.[15] Another series by Khanna et al., reported that mature teratoma were predominantly cystic and immature teratoma was
partly solid and partly cystic.[13] According to a review, majority of benign sacrococcygeal teratoma were cystic in
nature.[15] In our study, majority of the mature teratoma were predominantly cystic while immature
teratoma was mostly solid.
On histopathology, the majority of sacrococcygeal teratoma are mature followed by
immature teratoma. In our study, Grade 0 or mature teratomas are most commonly seen
(53%).
Our findings confirm the results by other studies.[6],[11],[16],[17],[18],[19],[20] According to Valdiserri and Yunis, 51 cases of mature sacrococcygeal teratoma were
classified as Grade 0. Among 8 immature teratomas, 2 were Grade 2 and 6 were Grade
3.[6] In the study, the major components of mature teratoma were ectodermal and endodermal
tissues followed by mesodermal and organoid elements. All the immature teratomas in
our study were composed of neuroepithelial elements. Two cases of malignancy have
been reported in our study where, yolk sac tumor is the malignant component. Some
say size is independent of biological behavior [Table 3].
Table 3
Comparison of different studies with the present study
|
Parameter
|
William et al.
|
Valdiserri et al.
|
Khanna et al.
|
Ramani et al.
|
Our study
|
|
Total cases
|
103
|
68
|
41
|
25
|
13
|
|
Age incidence (<2 month), (%)
|
79 (76)
|
54 (79)
|
23 (56)
|
18 (72)
|
9 (69)
|
|
Male:female
|
1:4
|
1:4
|
2:1
|
1:4
|
1:2
|
|
Clinical presentation
|
Sacrococcygeal
|
Sacrococcygeal
|
Sacrococcygeal
|
Sacrococcygeal
|
Sacrococcygeal
|
|
mass
|
mass
|
mass
|
mass
|
mass
|
|
Tumour maturity (%)
|
Mature: 73 (70)
|
Mature: 51 (75)
|
Mature: 31 (76)
|
Mature: 20 (80)
|
Mature: 7 (53.4)
|
|
Immature: 30 (29)
|
Immature: 8 (12)
|
Immature: 5 (12)
|
Immature: 5 (20)
|
Immature: 4 (30.8)
|
|
|
Malignant: 9 (13)
|
Malignant: 5 (12)
|
|
Malignant: 2 (15.4)
|
However, larger tumors are more likely to have immature histology and may have greater
intraoperative complications.[16] Mature teratoma should not recur if complete surgical excision and coccygectomy
are done. Persistently, elevated alpha fetoprotein levels may indicate a residual
or recurrent tumor.
Conclusion
Sacrococcygeal teratoma is the most common congenital neoplasm presenting at birth.
Sacrococcygeal teratomas when diagnosed at birth usually reveal fully differentiated
tissues and are benign. Meticulous search for the immature or malignant component
should be instituted as it helps in therapeutic decisions. Immature tissue in sacrococcygeal
teratoma is predominantly neuroepithelial. Histopathological grading of immature tissue
in sacrococcygeal teratomas does not correlate directly with prognosis. Early diagnosis
influences clinical decision and management, providing a better outcome. Continued
follow-up (with alpha-fetoprotein and radiology) to rule out recurrence.
More effective antenatal screening, for early diagnosis and management, to reduce
the risk of malignant transformation, hence better prognosis.
