Eble JN, Sauter G., Epstein JI, Sesterhenn IA - iarc

small tumour insufficient to produce a
palpable or macroscopic mass or at the
edge of a large tumour; intratubular infiltration;
pagetoid spread along the rete.
Seminoma cells are round or polygonal
with a distinct membrane. Cytoplasm is
usually clear reflecting the glycogen or
lipid content. Less commonly, they have
more densely staining cytoplasm. Nuclei
contain prominent nucleoli, which may
be bar shaped. Mitoses are variable in
number.
A
Fig. 4.16 Seminoma. A Transverse ultrasound image of the testis shows a large, well defined, uniformly hypoechoic
mass (white arrow). A small rim of normal, more hyperechoic, parenchyma remains (black arrows).
B Longitudinal ultrasound image of the tesits shows lobular, well defnined, hypoechoic mass (arrows).
Imaging
Seminoma has one of the more sonographically
characteristic appearances
of the testicular tumours. They are generally
well defined and uniformly hypoechoic.
Seminomas can be lobulated or
multinodular; however, these nodules are
most commonly in continuity with one
another. Larger tumours can completely
replace the normal parenchyma and may
be more heterogeneous.
Tumour spread
Seminoma metastasizes initially via lymphatics
to the paraaortic lymph nodes,
and afterward to the mediastinal and
supraclavicular nodes. Haematogeneous
spread occurs later and involves liver,
lung, bones and other organs.
B
uniform cells arranged in sheets or divided
into clusters or columns by fine
fibrous trabeculae associated with a lymphocytic
infiltrate, which may be dense
with follicle formation. Plasma cells and
eosinophils may also occur on occasion.
Less frequently appearances include
dense fibrous bands and "cystic" spaces
produced by oedema within the tumour.
Granulomatous reaction and fibrosis are
common and occasionally so extensive
that the neoplasm is obscured. Seminomas
usually obliterate testicular architecture
but other growth patterns include:
interstitial invasion (or microinvasion) in a
Variants
Cribriform, pseudoglandular and tubular
variants of seminoma
The seminoma cells may be arranged in
a nested pseudoglandular/alveolar or
“cribriform” pattern with sparse lymphocytes
{549}. A tubular pattern may occur,
resembling Sertoli cell tumour {2892}.
Confirmation of pure seminoma may
require demonstration of positive staining
for placental alkaline phosphatase
(PLAP) and CD117 (C-Kit) with negative
staining for inhibin, alpha-fetoprotein
(AFP) and CD30.
Seminoma with high mitotic rate
Seminomas with a greater degree of cellular
pleomorphism, higher mitotic activity
and a sparsity of stromal lymphocytes
have been called atypical seminoma,
Macroscopy
The affected testis is usually enlarged
although a proportion of seminomas
occurs in an atrophic gonad. A small
hydrocoele may be present but it is
unusual for seminoma to spread into the
vaginal sac. Veins in the tunica are prominent.
Characteristically a seminoma
forms a grey, cream or pale pink soft
homogeneous lobulated mass with a
clear cut edge and may have irregular
foci of yellow necrosis. Cyst formation
and haemorrhage are uncommon.
Nodules separate from the main mass
may be seen and occasionally the tumour
is composed of numerous macroscopically
distinct nodules. Tumour spread into
the epididymis and cord is rare.
Histopathology
Seminomas are typically composed of
A
B
Fig. 4.17 Seminoma. A Typical homogenous whitish seminoma. B Nodular architecture.
A
B
Fig. 4.18 Seminoma. A Seminoma cells with finely granular eosinophilic cytoplasm. B Intratubular typical seminoma.
Germ cell tumours 231