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Testis and epididymis

Germ cell tumors

Spermatocytic seminoma

Authors: Rafael Jimenez, M.D., Mayo Clinic, Nat Pernick, M.D., PathologyOutlines.com, Inc. (see Authors page)

Revised: 14 January 2010, last major update - January 2010

Copyright: (c) 2002-2010, PathologyOutlines.com, Inc.

Definition

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● Germ cell tumor not related to classic seminoma; does not arise from intratubular germ cell neoplasia

● Contains 3 cell types, varying from lymphocyte size to multinucleated giant cells, but mostly composed of intermediate sized cells

Epidemiology

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● Rare; 1-4% of all seminomas (J Urol 2007;178:125)

● Mean age 55 years, but also occurs in younger patients (Eur Urol 2004;45:495)

● Note: the most common testicular tumor in men age 60+ years is diffuse large B cell lymphoma

Etiology

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● Unlike classic seminoma, does not arise from intratubular germ cell neoplasia

● May derive from differentiated spermatogonia

Clinical features

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● Only occurs in descended testes (not extragonadal or in the female gonad)

● Benign (rare documented cases with metastases), but 6% are associated with a sarcomatous component, distant metastases and poor prognosis (AJCP 1990;94:89, AJSP 1988;12:75)

Prognostic factors

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● Sarcomatous component is poor prognostic factor (Am J Surg Pathol 1988;12:75)

Case reports

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● 45 year old man with nontender mass (Bostwick Laboratories)

● 55 year old man with tumor that underwent rhabdomyosarcomatous transformation (J Cancer Res Ther 2009;5:213)

Treatment

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● Orchiectomy

Gross description (Macroscopy)

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● Pale gray, mucoid, edematous

● Soft, friable cut surface

● Mean 7 cm

● 10% bilateral

Gross images

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Mucoid tumor                                                      Nodular gray-white tumor                Cystic and mucoid tumor

Micro description (Histopathology)

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● Nodules of cells with edema filled spaces causing pseudoalveolar appearance

Three types of cells:

● Small cells (6-8 microns) with narrow rim of eosinophilic cytoplasm resembling lymphocytes

● Medium cells (15-18 microns) with round nuclei, filamentous chromatin and eosinophilic cytoplasm (resemble spermatocytes but diploid)

● Giant cells (50-100 microns) with one or more nuclei

● Increased number of apoptotic cells (Mod Pathol 2007;20:1036)

● May have numerous mitoses

● Usually no stroma, no lymphocytes, no glycogen, no granulomas

● Usually not associated with intratubular germ cell neoplasia or other types of germ cell neoplasia

● 6% of cases are associated with a sarcomatous component, which is usually intermingled with the spermatocytic seminoma cells

● The sarcomatous component is usually undifferentiated or shows muscle differentiation

● Anaplastic variant: focal areas of predominantly medium cells containing prominent nucleoli; no clinical evidence of aggressive behavior (Hum Pathol 1996;27:650)

Micro images

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Diffuse growth pattern                                      Large nodules have focal pseudoglandular pattern

Intermediate cells have filamentous chromatin                                        Polymorphic nuclei

and prominent nucleoli

Polymorphic population of mainly small cells with dark nuclei,

intermediate cells with pale nuclei and occasional multinucleated giant cells

Extensive intercellular edema causes a                      Edema has caused a cystic pattern

pattern of small nests, trabeculae,

clusters and single cells

Edema fluid-filled spaces                                                 Numerous apoptotic cells

No lymphocytes or granulomas                                                                                                                                    

Intratubular growth:  note the filamentous (“spireme”)           Intratubular growth: one tubule

chromatin in some of the larger cells                                           shows normal spermatogenesis

Unusual features:

Prominent granulomatous reaction                              Tumor nests and cords mixed

and lymphoid infiltrate                                                      with lymphocytes

MAGE-A4+ (also present in spermatogonia)

Rhabdomyosarcomatous component is desmin+

Intratubular component surrounded by       Sarcomatous component                               

sarcomatous growth with features of

embryonal rhabdomyosarcoma

Cytology description

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● Clean background; three populations of cells (small, medium, and large), with a preponderance of medium-sized cells showing visible nucleoli; low mitotic rate; no lymphocytes (Diagn Cytopathol 1999;20:233)

Cytology images

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Numerous small lymphocyte-like cells, intermediate cells with filamentous chromatin, and rare giant cells

Positive stains

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● CAM5.2 (40%)

Negative stains

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● Keratin (may have focal staining), EMA, PLAP, OCT3/4 (Am J Surg Pathol 2004;28:935), hCG, AFP, CEA, EMA, CD30

● Also HPL, NSE, Angiotensin 1 converting enzyme (ACE)

Electron microscopy descriptions

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● Cytoplasmic bridges between tumor cells resembles those between spermatocytes

● Thickening of plasma membrane, microtubules between cells

● Minimal or no glycogen

Electron microscopy images

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Intercellular bridge joins two tumor cells, as in normal spermatocytes.

A nest of spermatocytic seminoma is surrounded by a well defined basement membrane;

there are numerous mitochondria, a Golgi apparatus and round nuclei with dispersed chromatin

Molecular / cytogenetics description

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● Gain of #9 (Cancer Res 2006;66:290)

Differential Diagnosis

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● Classic seminoma: fibrous stroma with prominent lymphocytes, often granulomatous reaction, seminoma cells have squared off nuclei; also intratubular germ cell neoplasia; lacks 3 cell types; PLAP+, PAS+ (glycogen), OCT3/4+

● Embryonal carcinoma: has markedly atypical cells, intratubular germ cell neoplasia; lacks 3 distinct cell types, AE1-AE3+, OCT3/4+, CD30+

Additional references

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● Arch Pathol Lab Med 2009;133:1985

End of Testis and epididymis > Germ cell tumors > Spermatocytic seminoma

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