Teratoma



Teratoma


Steven S. Shen, MD, PhD

Jae Y. Ro, MD, PhD










This mature teratoma shows squamous image and respiratory epithelium image, seromucinous glands image, and cartilage image. Virtually all somatic tissue types may be seen in a teratoma.






Immature teratoma shows neuroectodermal cells and neural tube-like structures image. Focal necrosis image and cellular spindle immature mesenchymal tissue image are also present.


TERMINOLOGY


Synonyms



  • Mature teratoma, immature teratoma


Definitions



  • Tumors with > 1 somatic tissue of different germinal layers (ectoderm, mesoderm, or endoderm)


ETIOLOGY/PATHOGENESIS


Genetics



  • Pediatric teratomas are diploid


  • Adult teratomas are often aneuploid (hypotriploid)


CLINICAL ISSUES


Epidemiology



  • Incidence



    • Pure form constitutes 4-9% of all testicular tumors



      • 2nd most common childhood germ cell tumor after yolk sac tumor in infants and young children


      • Pure teratoma in adults is extremely rare


    • Frequently mixed with other germ cell tumor types (approximately 50%)


  • Age



    • Occurs in 2 distinct age groups: Pediatric (< 4 years of age) and adults (2nd to 4th decades)


Presentation



  • Painless firm testicular mass


Treatment



  • For teratoma in prepubertal children, orchiectomy without lymph node dissection


  • For teratoma in adults, regardless of maturation, at least orchiectomy with close follow-up


Prognosis



  • Prepubertal teratomas are almost always benign


  • Adult teratomas are considered malignant because of relatively high recurrence or metastasis (22-37%)


IMAGE FINDINGS


General Features



  • Solid and cystic testicular mass by ultrasound


MACROSCOPIC FEATURES


General Features



  • Often well-circumscribed, nodular and firm mass with heterogeneous cut surface with solid and cystic areas


  • Cysts filled with clear, white, flaky, gelatinous or mucoid material


  • Mature tissue with hair, cartilage, bone, or teeth may be seen


Size



  • Variable


MICROSCOPIC PATHOLOGY


Histologic Features



  • Mature teratoma



    • Composed of mixture of elements of ectoderm, endoderm, and mesoderm



      • Ectoderm: Epidermis, neuronal tissue


      • Endoderm: Gastrointestinal or respiratory mucosa, other seromucous glands


      • Mesoderm: Bone, cartilage, muscle


    • Most common components are different types of epithelia, cartilage, or nerve


    • Respiratory and gastrointestinal epithelium, muscle, and cartilage are more commonly seen in testis than in ovary



    • Pancreatic, dental, renal, and thyroid tissue are less commonly seen in testis than in ovary


  • Immature teratoma



    • Primitive mesoderm: Undifferentiated spindle cell component (most common immature element in testis)


    • Primitive endoderm and primitive neuroectoderm (resembling neural tube and embryonic nervous system)


    • Blastomatous tissue (resembling blastema and embryonic tubules of developing lung or kidney), embryonic rhabdomyoblastic tissue


    • Teratoma with secondary malignant (somatic type) transformation



      • Sarcomatous transformation of teratoma: Foci of embryonal rhabdomyosarcoma, Wilms tumor-like element, or angiosarcoma


      • Carcinomatous elements in teratoma (such as squamous cell carcinoma, adenocarcinoma) with invasive growth


      • When histology of malignant component forms pure nodule of substantial size (> 1 field of 4x objective)


Cytologic Features



  • Highly variable and depends on tissue type and maturity


Predominant Pattern/Injury Type



  • Neoplastic


Predominant Cell/Compartment Type



  • Variable tumor cells from > 1 germ cell layer


ANCILLARY TESTS


Immunohistochemistry



  • Highly variable and depends on component of teratoma (rarely necessary in clinical practice)



    • Cytokeratin, CEA, and EMA/MUC1: Positive in epithelial tissue or carcinoma of teratomatous type


    • Vimentin: Positive in mesenchymal tissue


    • Germ cell markers: HCG (syncytiotrophoblastic cells), AFP (enteric and hepatoid tissue), PLAP (may be glandular tissue)


    • Other tissue specific markers for different type of tissues


DIFFERENTIAL DIAGNOSIS


Primary or Metastatic Sarcoma

Jul 7, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Teratoma
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