Teratoma (Dermoid)
Etiology & Epidemiology:
- Immature teratoma:
- First three decades most frequently
- Mediastinum:
- Adolescents most frequently
- Females always are mature teratomas
- Immature teratomas:
- Males only
- Children and adolescents
- Malignant teratoma:
- Klinefelter
syndrome:
- Increased risk of developing germ cell tumours, particularly extragonadal
Common sites:
- Ovary
- Testis
- Midline:
- Anterior mediastinum / thymus
- Pineal gland
- Retroperitoneum
- sacrococcygeal
Gross features:
- Ovary:
- bilateral 10-15%
- usually unilocular
cyst
- cyst contains hair and cheesy sebaceous
material
- thin wall lined by opaque, gray-white, wrinkled
epidermis, frequently with hair growing from it
- commonly areas of calcification in wall
- immature (malignant) teratoma:
- almost always largely solid
- areas of necrosis and hemorrhage
- hair, cartilage, bone, calcification may be
present
- testis:
- large (5-10cm)
- heterogenous appearance
- solid, cartilagenous,
cystic areas
- hemorrhage & necrosis if mixed with
embryonal or choriocarcinoma
- mediastinum:
- mature teratoma:
- often cystic
- brown fluid or oily or grumous
materials with or without hair
- encapsulated
- variegated cut surface
- fatty tissue
- medullary soft tissue
- flecks of cartilaginous tissue
- immature teratoma:
- large (often over 1 kg)
- solid
- adhere to or invade adjacent structures and
organs
Histologic features:
- heterogeneous collection of differentiated cells
and organoid structures, such as:
- clusters of squamous epithelium
- brain substance
- intestinal wall
- neural tissue
- muscle bundles
- islands of cartilage
- thyroid gland structures
- bronchial or bronchiolar epithelium
- embedded in a fibrous or myxoid
stroma
- Rare microscopic foci of immature neural tissue
may occur
- immature areas:
- tissues in various stages of maturation from
embryonic to fetal
- organized tissues and stroma composed of small
blue cells
- immature mesenchyme – very cellular, spindle
cells
- immature teratoma
(malignant):
- contains variable amounts of immature
(typically primitive/embryonal neuroectodermal)
tissues
- neuroectodermal tubules and rosettes mostly
- overlapping, hyperchromatic cells lining
- numerous mitoses
- pigmented maybe
- cellular mitotically active glia maybe
- admixed with ectodermal and endodermal
elements with varying degrees of maturation
- immature cartilage, adipose tissue, bone, and
skeletal muscle often
- embryoid bodies maybe (most primitive component)
- yolk sac epithelium and germ disc whose
epithelium resembles that of embryonal carcinoma
- Grading:
- Low-grade (grade 1):
- Rare foci of immature neuroepithelial
tissue
- < 1 low power field (40X) in any slide
- High-grade (grade 2/3):
- Grade 2:
- 1-3 low power fields (40X) in any slide (immature
neuroepithelial tissue)
- Grade 3:
- > 3 low power fields (40X) in any slide (immature
neuroepithelial tissue)
- Mediastinum:
- Mature teratoma:
- Skin and appendages (constantly)
- Bronchial tissue
- Gastrointestinal mucosa
- Smooth muscle
- Fat
- Bone
- Cartilage
- Exocrine and endocrine pancreas
- (not seen in teratomas
of the gonads)
- Salivary gland
- CNS including ependyma
- Immature teratoma
- Occasionally microscopic foci fo nongerm cell malignant
tumours
- Malignant transformation of mature cystic teratoma:
- germ cell tumour
- Squamous cell carcinoma
- Adenocarcinoma
- Poorly-differentiated carcinoma
- Adenosquamous carcinoma
- Sarcoma
- Embryonal rhabdomyosarcoma
- Angiosarcoma
- Myxoid liposarcoma
- Chondrosarcoma
- Leiomyosarcoma
- GBM
- Neuroblastoma
- Nephroblastoma
- Often presence of embryonal, yolk sac, and choriocarcinoma
- Monodermal
teratoma:
- Struma ovarii:
- Mature teratoma
composed exclusively or predominantly of thyroid tissue
- Microfollicular architecture maybe
- Sertoliform tubules maybe
- Solid areas with abundant eosinophilic or
clear cytoplasm maybe
- Edematous or fibromatous stroma maybe
- Thyroglobulin and TTF1 positive
- Benign
- Carcinoma may arise within similar to thyroid
- Favourable outcome in
general
- carcinoid
- grossly uniformly solid, or a nodule/mass
within a dermoid cyst or struma ovarii or a mucinous cystic tumour
- insular carcinoid most common
- small acini and solid nests
- trabecular carcinoid is less common
- strumal carcinoid: associated with struma ovarii (25-45%)
- intestinal-type mucinous glands component
frequently
- TTF1- / CK7- in carcinoid component
- Mucinous (goblet cell) carcinoid is rare
- stroma may be striking and often fibromatous
- almost invariably benign
- mucinous carcinoid may have an aggressive behavior
particularly if associated with atypical features
-
Immunophenotype:
Marker:
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Sensitivity:
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Specificity:
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Molecular features:
Other features:
- behaviour
depends on age in males:
- benign in children
- malignant
post-puberty
- mature teratoma
- benign except if malignant transformation
occurs
- peritoneal implants composed entirely of mature
glial tissue may occasionally be observed in cases of mature solid teratoma, but do not adversely affect prognosis
- rarely immature teratoma
develops in residual ovary after excision of a dermoid cyst,
particularly if the latter was multiple or had ruptured
- immature teratoma
- chemotherapy has improved prognosis
- stage and grade of the primary tumour and metastases remain important predictive
factors
- prognosis remains favourable
even in presence of innumerable military nodules of mature glia in the
peritoneum and abdominal lymph nodes
References:
- Kumar V, Fausto N, Abbas A. Robbins & Cotran Pathologic Basis of Disease, Seventh Edition.
7th ed. Saunders; 2004:1552.
- Shimosato
YM, Mukai KM. Tumors of the Mediastinum. American Registry of Pathology;
1998.
- Kurman
RJ, Carcanjiu ML, Herrnington
CS, Young RH. WHO Classification
of Tumours of Female Reproductive Organs (2014)
- (monodermal teratoma and somatic-type tumours
and immature teratoma section)