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

Tumours of paratesticular structures
C.J. Davis
P.J. Woodward
L.P. Dehner
M.A. Jones
J.R. Srigley
I.A. Sesterhenn
W.L. Gerald
M. Miettinen
J.F. Fetsch
Adenomatoid tumour
Definition
A benign tumour of mesothelial cells
characterized by numerous gland-like
spaces, tubules or cords.
Synonym
Benign mesothelioma.
ICD-O code 9054/0
Incidence
Adenomatoid tumours are the most common
tumours of the testicular adnexa,
representing 32% of all tumours in this
location {287,1800} and 60% of all
benign neoplasms in this area {2664}.
Clinical features
Signs and symptoms
These begin to appear in the late teens
and up to 79 years and most are seen in
A
the third through the fifth decades (mean
age 36 years) {1800}. They present as
small, solid intrascrotal tumours, and are
usually asymptomatic. They have typically
been present for several years without
appreciable growth and are uniformly
benign {1800,2664}.
Imaging
Adenomatoid tumours are smooth,
round, and well circumscribed masses of
variable size generally arising in the epididymis.
They are typically described as
hyperechoic and homogeneous. This
should not, however, be considered
characteristic as great variability has
been reported {801,1475}. The most
important point is to clearly identify the
mass as extratesticular and if it can be
shown to be arising from the epididymis,
adenomatoid tumour is the most likely
diagnosis. They may also arise from the
spermatic cord and tunica albuginea,
Fig. 4.94 Adenomatoid tumour. A Longitudinal ultrasound image shows a well defined, slightly hypoechoic,
extratesticular mass in the region of the epididymal tail (cursors). (T - testis). B Coronal, gadolinium
enhanced, T1-weighted MR image of scrotum shows an enhancing mass in the left epididymal head (black
arrow). The epididymis on the right is normal (white arrow). (T - testes).
B
where they can grow intratesticularly. The
latter presentation is indistinguishable
from testicular germ cell neoplasms.
Localization
Most of these occur in or near the lower
pole or upper pole of the epididymis but
other sites include the body of the epididymis,
the tunica vaginalis, tunica
albuginea and rete testis. Rarely the parietal
tunica or spermatic cord may be
involved {1800}.
Macroscopy and histopathology
These are usually small tumours, 2.0 cm
or less, but they have ranged from 0.4 to
5.0 cm {2051}. They are round or oval
and well circumscribed although they
can also be flattened and plaque-like.
Microscopically these consist of
eosinophilic mesothelial cells forming
solid cords as well as dilated tubules with
flattened lining cells which may initially
suggest an endothelial appearance
{166}. Vacuolated cytoplasm is a prominent
feature of the cells. The stroma is
usually fibrous but may consist largely of
smooth muscle.
Ultrastructural and immunohistochemical
features of these tumours support their
mesothelial cell origin. There is an
absence of epithelial/carcinoma markers
MOC-31, Ber-Ep4, CEA, B72.3, LEA 135
and Leu M1 and also factor VIII and
CD34. They invariably express cytokeratin
AE1/AE3 and EMA {586,589}.
Malignant mesothelioma
Definition
Malignant tumours originating from the
tunica vaginalis or tunica albuginea.
ICD-O code 9050/3
A
Fig. 4.95 Adenomatoid tumour. A Adenomatoid tumour protruding into the testis. B Paratesticular adenomatoid
tumour.
B
Incidence
Intrascrotal mesotheliomas are invariably
described as rare although they are the
most common paratesticular malignancies
after the soft tissue sarcomas
{287,1239,2051}. As of the year 2002
Tumours of paratesticular structures 267