MIXED BRENNER AND ADENOMATOID TUMOR
OF THE TESTIS
An Ultrastructural Study and Histogenetic Considerations
F. NOCALES JR., MD,* ALFREDO
MD,$ AND TOMAS
A previously unreported association of Brenner and adenomatoid tumor found
in the tunica vaginalis testis is presented. Many ultrastructural features found
in mesothelial cells such as intercellular spaces, deeply indented nuclei, tono-
filaments and tight desmosomes;were also shared by cells present in both neo-
plastic patterns. The previous histogenetic origins ascribed to testicular Bren-
ner tumors are discussed and the evidence for their origin in the mesothelium
Cancer 43:539-543, 1979.
D there exist marked resemblances be-
tween the tumoral varieties found in both fe-
male and male genital structures, with obvious
variations in their relative frequency. While
adenomatoid tumors are a usual finding in
both sexes, Brenner tumors are common in
the ovary but constitute a highly unusual neo-
plasm of the testis; until now only two fully
documented cases have been rep~rted.~,~
present an ultrastructural study of a hitherto
unreported mixed Brenner and adenomatoid
tumor. We feel that this coincidental finding
may help to clarify certain aspects of the histo-
genetic origin of the Brenner tumor in the
UE TO A basically similar histogenesis,
Material for study was available from a
rounded, painless, partly cystic mass of 3 cm in
its maximal diameter, which had been re-
moved from the testis of a 37-year-old man.
The tumor was situated in the tunica vaginalis
2 cm caudally from the epididymis. The
tumor and a small subalbugineal quantity of
testicular tissue were thoroughly blocked for
light microscopy. Fresh tissue for electron-
From the Department of Pathology, University of
Seville Medical School, Seville, Spain.
* Associate Professor.
Address for reprints: Francisco F. Nogales Jr., MD,
Hospital Universitario, Avda. Dr. Fedriani, s/n, Seville,
Accepted for publication April 10, 1978.
microscopy was fixed in 4% glutaraldehyde,
osmicated, embedded in Epon-Araldite and
studied with a Siemens 102 electronmicro-
Light microscopy revealed an adenomatoid
tumor as the predominant pattern (Fig. l),
consisting of narrow channels lined by flat-
tened or cuboidal regular cells. Other areas
showed cords of rounded epithelioid cells with
a faintly eosinophilic cytoplasm and vesicular
nuclei. Intimately admixed and randomly
situated within the tumor were numerous
Brenner nests (Fig. 2) formed by small regular
cells with acidophilic cytoplasm and well-de-
fined cytoplasmic borders, whose ovoid nuclei
often presented a “coffee-bean’’ appearance.
Most of the nests had a central cavitation lined
by tall columnar epithelium and occasionally
filled with cellular debris. The stroma was
dense in all areas.
Ultrastructurally, both neoplastic patterns
were evident. In the adenomatoid areas, the
lining cells of the tubules showed variation in
size and shape, but flattened or cuboidal cells
predominated resting on a thin basal lamina.
Complex cell borders delineated intercellular
spaces (Fig. 3). The cell surface presented
abundant and well-developed elongated
microvilli of varying size, which were also
evident at the interfaces between adjoining
cells as well as in intracellular luminal forma-
tions. The cytoplasm contained abundant
micropinocytotic vesicles in the basal cell por-
0008-543X/79/02001053Y $0.75 0
American Cancer Society
FIG. 1. Predominant pattern of adenomatoid tumor
(H & E, X160).
tions (Fig. 4), as well as abundant bundles of
microfilaments of about 100 8, thick, often re-
lated to well-formed desmosomes. Among
other organelles, profiles of granular endo-
plasmic reticulum and free ribosomes were
plentiful. The rounded or ovoid nuclei
showed deep infoldings often in a central posi-
tion, bisecting the nucleus and giving a bi-
The areas corresponding to Brenner nests
were separated from the surrounding fibro-
blasts by a well-developed basal lamina. Com-
plex interdigitations interlocked their plasma
membranes which were otherwise joined by
tight desmosomes. Smaller intercellular
spaces than those found in the adenomatoid
areas were present and these showed elon-
gated projections of cytoplasm. Neither well-
formed microvilli nor micropinocytotic
vesicles were found. Microfilaments were con-
spicuous in the cytoplasm as well as poorly
preserved mitochondria and ribosomes. Deep
clefts were seen in the nuclei (Fig. 5) which
correlated with the typical "coffee-bean'' ap-
pearance observed by light microscopy. The
stroma consisted of scanty fibroblasts without
any special features, surrounded by thick
bundles of collagen fibers.
The histogenetic origins of the Brenner and
adenomatoid tumor have caused much con-
troversy. Possible origins for the Brenner
tumor have been considered in f~llicular'~
mesenchymal,s teratoid,6 mesonephri~,~,"
mullerian5 and mesothelial (surface ce-
lomic epithelium cells).2s12 Many histogenetic
sources for the adenomatoid tumor have also
been discussed, including endothelial, meso-
nephri~,~ mulle~-ian'~ and finally, mesothelial
origin^,^,'^ as was originally proposed by
In recent years, evidence has accumulated
which strongly suggests an origin for both
tumors from mesothelial cells, the ovarian ce-
lomic surface epithelium being considered as
a specialized mesothelium. This evidence has
arisen in the Brenner tumor due to Arey's re-
construction studies' which show the con-
tinuity between the ovarian surface epithe-
lium with that of the Brenner nests. Recently,
many ultrastructural similarities have been
found between the cells of the Brenner tumor,
celomic surface, Walthard nests and urothe-
The obvious ultrastructural and histo-
FIG. 2. Several Bren-
ner epithelial nests with
central cavitation are
seen interspersed among
an adenomatoid tumor
pattern (H & E, X80).
Inset: Epithelial cells
from a Brenner nest
showing a central nu-
clear groove (H & E,
FIG. 3. Adenomatoid tumor area; intercellular spaces (ICS) between cells joined by desmosomes (arrow). Microvilli
forming intracellular lumens (ICL) are seen. Observe deeply indented, bilobulated nucleus and abundant microfila-
ments between the two nuclear lobes (~4600).
FIG. 4. Lining from
a tubule in adenoma-
toid area; micropino-
cytotic vesicles (arrow)
are seen near the
basal lamina (BL).
Bundles of microfila-
ments and apical elon-
gated microvilli are evi-
chemical resemblances between the adenoma-
toid tumor cells and both the neoplastic and
normal mesothelial cells of the pleura and
peritoneurn3,l4 have made the mesothelial
origin for this tumor widely accepted.
The present study provides further evi-
dence for a mesothelial origin for both neo-
plasms as each tumoral pattern was found in
close association and shared certain ultra-
structural features. These included intra-
cellular spaces lined by cytoplasmic projec-
tions, which, although more evident in adeno-
matoid areas, were also present in the
Brenner tumor components, as well as deeply
indented nuclei and other less specific features
such as tight desmosomal contacts and cyto-
plasmic microfilaments. All these morpho-
logic characters have been consistently found
in the studies of the normal and neoplastic
Their ultrastructural similarity however, is
not complete, as certain cytoplasmic speciali-
FIG. 5. Basal area
from a Brenner epithe-
lial nest; nuclei show
deep central clefts. A
small dilated intercellu-
lar space is seen (ar-
arrow) and a thin basal
lamina (BL) are present
zations such as an elaborate microvilli system,
often forming intracellular lumina and
pynocytotic vesicles are present in the adeno-
matoid tumor and mesothelium,3 but absent
in the Brenner tumor.
In the only two previous fully documented
reports of Brenner tumors of the testis, both
mesonephricg and parame~onephric~
have been considered; in the latter, a mul-
lerian origin was suggested as the tumor lay in
the epididymotesticular groove, where para-
mesonephric remnants are also occasionally
In the case reported here, both the Brenner
tumor and the adenomatoid tumor arose
from the tunica vaginalis, which is purely
mesothelial, and therefore far away from any
mullerian remnants. We feel that this, to-
gether with their many ultrastructural simi-
larities and their intimate association, is
strongly suggestive of a common origin of the
TUMOR . Nogales et al.
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