Testis & epididymis
Germ cell tumors
Seminoma


Topic Completed: 7 January 2020

Minor changes: 10 September 2020

Copyright: 2012-2020, PathologyOutlines.com, Inc.

PubMed Search: Seminoma testis [title]

Michelle R. Downes, M.D.
Page views in 2019: 42,049
Page views in 2020 to date: 32,581
Cite this page: Downes M. Seminoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/testisseminomas.html. Accessed September 20th, 2020.
Definition / general
  • Most common type of testicular germ cell tumor (up to 50%) and may occur as component of mixed germ cell tumor
  • Derived from transformed gonocytes
  • Consists of cells with well defined borders, (usually) clear cytoplasm, round to polygonal nuclei and prominent nucleolus
Essential features
  • Most frequent germ cell tumor of the testis
  • Presents in young men (30 - 49) with unilateral palpable mass
  • Typically a well demarcated, uniform neoplasm with characteristic cytological features and background of fibrous septae and lymphocytes
  • Germ cell markers (OCT 3/4, CD117) are useful in the diagnosis
  • Prognosis is stage dependent with excellent 5 year survival when clinical stage 1
Terminology
  • Seminoma: testicular primary (or mediastinal primary)
  • Dysgerminoma: same tumor but primary to the ovary
  • Germinoma: same tumor but primary to extragonadal sites (such as pineal gland)
ICD coding
  • ICD-10: C62.90 - malignant neoplasm of unspecified testis, unspecified whether descended or undescended
  • ICD0: 9061/3 - seminoma, NOS
Epidemiology
  • Male, age 30 - 49
  • Rare in > 70 or < 20 years
Sites
  • Testicle
Pathophysiology
  • Arises from germ cell neoplasia in situ (GCNIS)
  • GCNIS cells are proposed to arise from delayed maturation of primordial germ cells / gonocytes with polyploidization resulting in a transformed germ cell
  • This progresses post puberty into seminoma (most likely GCNIS evolves into intratubular seminoma and then invasive seminoma) (J Urol 1996;155:1938)
Etiology
Clinical features
  • Usual presentation is with a mass
  • < 5% present with metastatic symptoms
  • Paraneoplastic symptoms are rare (limbic encephalopathy, hypercalcemia, polycythemia, exophthalmus) (BMJ Case Rep 2014;2014:bcr2014206893)
  • Metastases are initially retroperitoneal and then progress to mediastinal and cervical nodes; visceral metastases develop late
Diagnosis
Laboratory
  • Serum LDH and PLAP may be elevated
  • hCG levels are increased in up to 20% of cases but elevation is modest (Pathol Annu 1991;26:59)
  • AFP should not be increased, if elevated think liver disease or nonseminoma component
Radiology description
  • Uniform, well delineated and hypoechoic mass on ultrasound
  • May be microlithiasis
Radiology images

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Ultrasound with testicle mass

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Parietal metastasis

Prognostic factors
  • Clinical stage 1 has 95 - 98% 5 year survival
    • > 40 years and advanced stage are poor prognostic features (nonpulmonary metastases)
Case reports
Treatment
  • Surgery (radical orchiectomy) for primary
  • Surveillance protocols used for stage 1 disease
  • Radiation (very radiosensitive tumor) and chemotherapy (platinum based) used in higher stage disease
  • Retroperitoneal lymph node dissection used for residual post chemotherapy disease (J Natl Compr Canc Netw 2012;10:502)
Gross description
  • Well demarcated, homogeneous, solid cream or grey tumors; surface nodularity and lobulation; may be multiple nodules
  • Necrosis or hemorrhage usually minimal
  • If regressed, only a scar may be visible
  • Usually confined to testis (90%)
Gross images

Contributed by Debra L. Zynger, M.D.
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pT1a

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pT1b

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pT2



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Very large seminoma

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Seminoma

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Lobulated soft tan to brown tissue

Frozen section description
  • Fibrous bands with lymphocytes and clear cells
  • Intra-operative smear / touch prep preparation will show large cells with abundant cytoplasm and admixed lymphocytes; tigroid type pattern (dense and light stripes) in air dried Giemsa smear
Frozen section images

Contributed by Michelle Downes, M.D.
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Intraoperative frozen section



Contributed by Debra L. Zynger, M.D.
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Pale, foamy cytoplasm


Microscopic (histologic) description
  • Sheets or lobular configuration of tumor with fibrous septae
  • Cells are typically pale (glycogen) but may be eosinophilic
  • Cell membranes are well defined with distinct cell boundaries
  • Nuclei are polygonal and may have a flat edge giving a squared off appearance; they contain one or more prominent central nucleoli; no nuclear overlap if well fixed tissue
  • A lymphocytic infiltrate is present (T lymphocytes) with plasma cells; germinal centers may occur
  • Granulomas noted in up to 50% of cases
  • Intercellular edema with microcystic spaces and coagulative type necrosis can be present
  • Multinucleated syncytiotrophoblasts can be seen in 20% of tumors and can produce hCG
  • Intratubular seminoma may be adjacent to invasive seminoma (30% cases)
  • Less frequent growth patterns include intertubular pattern (may not form a mass), corded growth, microcystic, tubular, signet ring appearance
  • Anaplasia referring to increased mitoses and pleomorphism within a seminoma is no longer reported (no correlation with outcome) (J Urol 1996;155:1938)
  • Fibrosis and sclerosis can indicate regressed or burnt out seminoma
  • Lymphovascular invasion is uncommon, especially in tumors under 4 cm, and should be differentiated from artifactual carry over (Am J Clin Pathol 2016;145:341)
  • Invasion of rete testis can be direct stromal invasion or pagetoid invasion; direct stromal invasion carries prognostic significance in seminoma (Am J Surg Pathol 2017;41:e22)
Microscopic (histologic) images

Contributed by Michelle Downes, M.D.
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Fibrous septae

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Admixed lymphocytes

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Large cells with clear cytoplasm

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Coagulative necrosis

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OCT 3/4

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CD117


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Granulomatous inflammation

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Granuloma

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Intratubular seminoma

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Rete testis invasion

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Rete testis pagetoid spread

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Hilar fat invasion


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Epididymal invasion

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Syncytiotrophoblasts

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hCG



Contributed by Debra L. Zynger, M.D.
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Discontinuous spermatic cord invasion


Cytology description
  • Discohesive population of large cells with moderate cytoplasm, round slightly irregular nuclei and one or more prominent nucleoli
  • Background population of small, mature lymphocytes
  • Classic “tigroid smear” seen mostly in hypercellular aspirates (J Cytol 2011;28:39)
Cytology images

Contributed by Michelle Downes, M.D.
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Intraoperative touch prep



Contributed by Debra L. Zynger, M.D.
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Large cells with prominent nucleoli

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Tigroid pattern


Negative stains
Molecular / cytogenetics description
Sample pathology report
  • Right testis, mass, radical orchiectomy:
    • Seminoma, 3.6 cm (see synoptic report)
    • Comment: Immunohistochemistry was performed and the tumor expresses OCT 3/4 and CD117. The cells are negative with CD30 and AFP. The immunoprofile supports the morphologic interpretation of seminoma.
Differential diagnosis
Board review style question #1
    Which of the following stains is appropriate for differentiating between seminoma and embryonal carcinoma?

  1. AFP
  2. CD30
  3. hCG
  4. OCT 3/4
  5. SALL4
Board review answer #1
B. CD30

Comment Here

Reference: Seminoma
Board review style question #2

    A 38 year old man presents with a unilateral, painless palpable mass in the left testis. His serum AFP and hCG are normal with mild LDH elevation. The histology of his orchiectomy specimen is shown. Where would be the most typical first site for metastasis?

  1. Bone
  2. Brain
  3. Groin nodes
  4. Lung
  5. Retroperitoneal nodes
Board review answer #2
E. Retroperitoneal nodes. This is a photo of seminoma.

Comment Here

Reference: Seminoma
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