Yolk Sac Tumor

Yolk Sac Tumor

Steven S. Shen, MD, PhD

Mahul B. Amin, MD

Jae Y. Ro, MD, PhD

H&E shows microcystic and reticular YST patterns in which tumor cells contain vacuolated cytoplasm, intercellular eosinophilic globules image, & extracellular pink basement membrane-like material image.

This image shows a Schiller-Duval body in YST, which is characterized by a central vessel surrounded by a layer of tumor cells, a hollow space, and another layer of similar or more flattened cells.



  • Yolk sac tumor (YST)


  • Endodermal sinus tumor (EST)


  • Germ cell tumor characterized by variety of growth patterns that recapitulate yolk sac, allantois, and extraembryonic mesenchyme



  • Incidence

    • Pure YST is most common testicular tumor of infants and young children

      • Accounts for 75% of all childhood testicular neoplasms

      • No association with cryptorchidism or other germ cell tumor components

    • Pure YST is extremely rare in adult testes

      • At extragonadal sites, especially mediastinum, pure YST may be seen

    • YST is frequent component of mixed germ cell tumors (in ~ 40%) in adults

  • Age

    • Mean age: 16-18 months for pure YST

    • Mean age: 25-35 years for adult YST

      • 10 years younger than patients with seminoma


  • Nonsymptomatic, rapid testicular enlargement

  • Approximately 90% of patients with childhood YST have clinical stage I disease

  • Presence of YST in adult patients with mixed germ cell tumor is frequently associated with lower stage presentation

Laboratory Tests

  • More than 95% patients have elevated serum α-fetoprotein (AFP)

  • Test for serum AFP is valuable tool in diagnosis and monitoring effectiveness of therapy


  • For infants and children with pure YST

    • Radical inguinal orchiectomy for stage I tumor with close follow-up protocol (surveillance)

    • Cisplatin-based therapy for relapse on surveillance, advanced stage disease, or metastasis

  • For adult YST (usually mixed with other germ cell tumor)

    • Similar to other nonseminomatous germ cell tumor based on clinical stage

    • Radical inguinal orchiectomy ± retroperitoneal lymph node dissection

    • Cisplatin-based chemotherapy for metastatic disease


  • Prognosis associated with clinical stage, lymphovascular invasion, degree of serum AFP elevation

  • Children have better prognosis than adults


General Features

  • Ultrasonography may detect scrotal mass


General Features

  • Nonencapsulated, gray-white, soft or firm, homogeneous mass

  • Typical myxoid or gelatinous cut surface

  • Hemorrhage and necrosis may be present

  • Tumors in adults are typically more heterogeneous


  • Range: 2-6 cm


Histologic Features

  • YST frequently has multiple growth patterns with 1 dominant pattern

    • Microcystic or reticular pattern most frequent (80%)

      • Anastomosing thin cords forming round or irregular spaces or tubules of variable size

      • Characteristic intracellular vacuoles and merging of cells create sieve-like appearance

      • Nuclei are irregularly shaped (round, columnar, stellate, triangular) and are often pushed to edge of cells

    • Endodermal sinus pattern

      • Composed of numerous Schiller-Duval bodies (resembling fetal glomeruli) with central fibrovascular core

      • Fibrovascular core is lined by cuboidal to columnar tumor cells, which are surrounded by cystic spaces and more flattened layer of tumor cells

      • Labyrinthine spaces or perivascular arrangement of tumor cells are common

    • Solid pattern

      • Solid sheets of polygonal tumor cells with pale eosinophilic or clear cytoplasm, which lack fibrovascular septae, lymphocytes, or granulomas

      • May be confused with seminoma, embryonal carcinoma, and monophasic areas of choriocarcinoma

      • Tumor cells with random pleomorphism; slightly greater atypia than seminoma but less than embryonal carcinoma

    • Papillary and tubulopapillary

      • Papillae ± central fibrovascular cores

      • Tumor cells are often cuboidal and low columnar with “hobnail” appearance

    • Polyvesicular vitelline pattern

      • Large constricted vesicles lined by flattened to cuboidal cells

      • Often associated with abundant myxoid or loosely fibrous stroma

    • Glandular-alveolar pattern

      • Simple round to complex branching glands with intervening myxoid stroma

    • Parietal pattern

      • Epithelial cells surrounded by pink bands of basement membrane material

    • Enteric or endometrioid pattern

      • Glandular pattern with columnar cells, cytoplasmic clearing, subnuclear vacuoles, and smooth luminal surface

    • Hepatoid pattern

      • Sheets of tumor cells with abundant eosinophilic cytoplasm and eosinophilic globules

    • Spindled cell or sarcomatoid pattern

      • Composed of spindle (or sarcomatoid) cells with myxoid stroma

    • Myxomatous pattern

      • Epithelioid to spindle cells dispersed in paucicellular light blue myxoid stroma

      • Frequently under-recognized due to innocuous appearance

    • Macrocystic pattern

      • Large cystic spaces due to coalescence of microcysts lined by flattened tumor cells

    • Mixed pattern

      • Mixture of any of above growth patterns

  • Intra- and extracellular PAS-positive hyaline globules

    • More commonly seen in microcystic and reticular, solid, and hepatoid patterns

Cytologic Features

Jul 7, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Yolk Sac Tumor

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