CHAPTER X CHAPTER 4 - Cancer et environnement

A
B
Fig. 4.09 Spermatocytic seminoma. A Example of G-banding on a metaphase spread. B Comparative genomic hybridization of DNA isolated from the same tumour.
Note the almost complete absence of structural anomalies, while numerical changes are present. Gain of chromosome 9 is the only consistent anomaly identified.
Precursor lesions
Intratubular germ cell neoplasia,
unclassified type (IGCNU)
Definition
Germ cells with abundant vacuolated
cytoplasm, large, irregular nuclei and
prominent nucleoli located within the
seminiferous tubules.
ICD-O code 9064/2
Synonyms
Intratubular malignant germ cell, carcinoma
in situ, intratubular preinvasive
tumour, gonocytoma in situ, testicular
intraepithelial neoplasia, intratubular
atypical germ cells and intratubular
malignant germ cells.
Epidemiology
Adults
In adults with history of cryptorchidism
intratubular germ cell neoplasia, unclassified
are seen in 2-4% {345,787,887,
1010,1124,2040,2131,2222} in contrast
to 0.5% in young children {501}. In infertility
studies, the prevalence is about 1%
{233,345,1900,2346, 2430,2943}) ranging
from 0-5%. Patients with intersex syndrome,
and a Y chromosome have
intratubular germ cell neoplasia of the
unclassified type (IGCNU) in 6-25% of
cases {118,387,1831,2140, 2826}. Testes
harbouring a germ cell tumour contain
IGCNU in a mean of 82.4% of cases,
ranging from 63 {889} -99% {346}. Since
the risk of tumour development in the
contralateral testis is increased about 25-
50 fold {615,1985, 2774}, some centres
in Europe have initiated biopsies of the
contralateral testis, with detection rates of
IGCNU of 4.9-5.7% {613,2749}. IGCNU is
detected in 42% of patients who presented
with retroperitoneal germ cell tumours
{262,555,1100} but is rarely found in
patients with mediastinal tumours {997}.
Several autopsy studies have shown that
the incidence of IGCNU is the same as
the incidence of germ cell tumours in the
general population {616,891}.
Children
In contrast to their adult counterpart, the
true incidence of prepubertal IGCNU is
difficult to assess. IGCNU has only rarely
been described in association with testicular
maldescent, intersex states and in
a very few case reports of infantile yolk
sac tumour and teratoma {1134,1381,
2018,2167,2482,2483}.
IGCNU is seen in association with
cryptorchidism is 2–8% of patients {1381}.
Four of 4 patients with gonadal dysgenesis
in one series had intratubular germ cell
neoplasia of the unclassified type (IGCNU)
{1833} as did 3 of 12 patients with androgen
insensitivity (testicular feminization)
syndrome {1831}. In review of the literature
Ramani et al. found IGCNU in 2 of 87
cases of different intersex states {2140}.
A
B
Fig. 4.10 Precursor lesions of germ cell tumours. A Intratubular germ cell neoplasia (IGCNU) adjacent to normal seminiferous tubules. B Positive PLAP staining in
the intratubular germ cell neoplasia (IGCNU) adjacent to normal seminiferous tubules.
228 Tumours of the testis and paratesticular tissue