Introduction
Uterine adenomatoid tumors (UATs) are benign tumors
of the uterine serosa and myometrium, originating from the
mesothelium and forming gland-like structures (1). UATs are incidentally discovered during
uterine surgery performed for other causes (1) and may resemble pre-existing
capillaries and lymphatic ducts, as well as metastatic
adenocarcinomas (2). Therefore, it
is important for surgical pathologists to determine the true
incidence of UATs. In one of the major textbooks of gynecological
pathology (2) it is reported that
UATs are discovered in ∼1% of hysterectomy specimens; however,
there is no citation of original studies.
In order to determine the true incidence of UATs,
large numbers of consecutive hysterectomy and uterus-preserving
tumor excision specimens should be thoroughly examined by a single
attending pathologist.
Materials and methods
Cases
A total of 199 consecutive surgical cases were
investigated over a period of 18 months. The cases were as follows:
66 vaginal hysterectomies [43 due to uterine prolapse, 18 due to
leiomyomas, three due to adenomyosis and two due to residual
high-grade squamous intraepithelial lesions (HSILs)], 26
laparoscopically-assisted vaginal hysterectomies (22 due to
leiomyomas and four due to adenomyosis), 31 transabdominal simple
hysterectomies (17 due to leiomyomas, 7 due to adenomyosis, one due
to atypical endometrial hyperplasia, one due to a large endometrial
polyp, two due to severe infection, two due to massive bleeding
following delivery and placenta increta and one due to torsion of a
benign ovarian cystic tumor), nine radical hysterectomies due to
malignant tumors and two total laparoscopically-assisted
hysterectomies due to adenomyosis. As summarized in Table I, the major indications for
hysterectomy were leiomyomas (57 cases), uterine prolapse (43
cases), adenomyosis (16 cases) and malignant tumors, including
residual HSIL and atypical endometrial hyperplasia (18 cases). The
remaining 65 patients underwent uterus-preserving tumor excisions
(64 laparoscopically-assisted and one transvaginal myomectomies),
following clinical diagnosis of large leiomyomas.
 | Table IRelationship between clinical
diagnosis and presence of UATs in 199 consecutive gynecological
surgical cases. |
Table I
Relationship between clinical
diagnosis and presence of UATs in 199 consecutive gynecological
surgical cases.
| Major clinical
diagnosis | No. of cases examined
[age in years (mean, range)] | No. of cases
diagnosed with UATs (%) |
|---|
| Hysterectomy | | |
| Leiomyomas | 57 (46, 36–66) | 4 (7) |
| Uterine
prolape | 43 (66, 50–81) | 1 (2) |
| Adenomyosis | 16 (45, 33–50) | 1 (6) |
| Other
conditions | 18 | 0 |
| Total | 134 (53, 21–85) | 6 (5) |
| Uterus-preserving
tumor excision | | |
| Leiomyomas | 65 (37, 26–53) | 3 (5) |
The study was approved by the Ethics Committee of
the Hiroshima General Hospital of West Japan Railway Company,
Higashi-ku, Hiroshima, Japan. Informed consent was obtained from
the patients or the patients’ families.
Analysis
A single attending pathologist (H.N.) performed a
macroscopic examination of the surgical specimens obtained from 199
consecutive cases handled by a single gynecological surgical team,
including two attending gynecologists (H.T. and M.T.). The
attending pathologist collected tissue samples macroscopically
resembling UATs for further histological examination. A diagnosis
of UAT was confirmed by immunohistochemical analysis, using
monoclonal antibodies to calretinin (clone DAK Calret 1;
DakoCytomation, Kyoto, Japan), podoplanin (D2-40; Nichirei
Bioscience, Tokyo, Japan), CK5/6 (D5/16B4; DakoCytomation), CK8
(CAM5.2; Becton-Dikinson, Tokyo, Japan), CD34 (QBEnd10;
DakoCytomation) and CD31 (JC/70A; DakoCytomation) (3).
Results
Incidence
As shown in Tables I
and II, UATs were identified in
nine (5%) out of the 199 cases investigated [six (5%) out of the
134 cases of hysterectomy and three (5%) out of the 65 cases with
uterus-preserving tumor excision]. One out of these nine cases
presented with two UATs. Accordingly, a total of 10 UATs were
identified during the present study.
| Table IIIncidence and size of UATs identified
in the present study. |
Table II
Incidence and size of UATs identified
in the present study.
| Surgical
procedure | No. of cases
examined | No. of cases with
UATs (%) | Mean age in years
(range) | Tumor size range in
cm |
|---|
| Hysterectomy | 134 | 6 (5) | 51 (44–67) | 0.5–2.5 |
| Uterus-preserving
tumor excision | 65 | 3a(5) | 34 (29–36) | 1.0–7.0 |
| Total | 199 | 9a(5) | 45 (29–67) | 0.5–7.0 |
Age
As summarized in Table
II, the age range of the nine patients diagnosed with UATs was
29–67 years (six hysterectomy patients, 44–67 years; three
uterus-preserving tumor excision patients, 29–36 years).
Tumor size
As shown in Table
II, the 10 UATs identified in the present study ranged in size
from 0.5 to 7 cm; five (84%) out of the six UATs that were
incidentally discovered in hysterectomy specimens at gross
examination were <1 cm in diameter, whereas the four (100%) UATs
identified in the three cases of uterus-preserving tumor excision
were >1 cm in diameter.
Clinicopathological characteristics of
the nine cases diagnosed with UATs
The clinicopathological characteristics are listed
in Table III. Among the
hysterectomy cases, case 2 presented with numerous nodular lesions
<7.5 cm in diameter, preoperatively detected by magnetic
resonance imaging (MRI) scans; one of these lesions, measuring 2.5
cm in diameter, was subsequently diagnosed as a UAT; the other
lesions were all confirmed as leiomyomas. The remaining five UATs
in cases 1, 3, 5, 7 and 8 were incidentally detected by the
attending surgical pathologist.
| Table IIIClinicopathogical characteristics of
the nine cases ultimately diagnosed with UATs. |
Table III
Clinicopathogical characteristics of
the nine cases ultimately diagnosed with UATs.
| Case no. | Age (years) | Preoperative UAT
detection | Other lesions
identified | Surgical
procedure | Size (cm) |
|---|
| 1 | 45 | Not detected | Leiomyomas | H | 0.6 |
| 2 | 44 | Misdiagnosed as a
leiomyoma | Leiomyomas | H | 2.5 |
| 3 | 48 | Not detected | Leiomyomas | H | 0.8 |
| 4 | 36 | Misdiagnosed as two
minor foci of adenomyosis (two UATs) | Leiomyoma | T | 1.0 |
| 5 | 53 | Not detected | Leiomyomas | H | 0.5 |
| 6 | 36 | Misdiagnosed as
adenomyosis | Leiomyomas | T | 3.0 |
| 7 | 67 | Not detected | Uterine prolapse | H | 0.6 |
| 8 | 50 | Not detected | Adenomyosis | H | 0.8 |
| 9 | 29 | Misdiagnosed as a
leiomyoma with degenerative change | None | T | 7.0 |
Among the cases of uterus-preserving tumor excision,
the gynecologists detected three nodular lesions by MRI in case 4;
one of these three lesions, measuring 6 cm in diameter, was
preoperatively diagnosed as a leiomyoma and the remaining two,
measuring 1 cm in diameter, were suspicious of adenomyosis. The
histopathological examination confirmed the diagnosis of a
leiomyoma and two UATs, respectively. The clinical diagnosis in
case 6 included leiomyomas and a large focus of adenomyosis; all
preoperatively diagnosed leiomyomas were histopathologically
confirmed as such and the large focus clinically misdiagnosed as
adenomyosis was in fact a UAT. Case 9 presented with the largest
UAT identified in the present study, which was preoperatively
misdiagnosed as a leiomyoma with degenerative change by MRI
scans.
Discussion
As mentioned above, according to one of the major
textbooks of gynecological pathology, UATs are identified in ∼1% of
hysterectomy specimens (2); this
textbook was also cited as a reference in another widely recognized
gynecological pathology textbook (4). However, those textbooks included no
citation of original studies. To the best of our knowledge, our
study is the first to report findings regarding the incidence of
UATs, since there are no available data on the subject in the
literature.
Total hysterectomy specimens enable pathologists to
examine the whole uterus. Therefore, hard data on the true
incidence of UATs may only be obtained through the study of total
hysterectomy specimens, since all UATs <1 cm in diameter were
incidentally discovered in hysterectomy specimens. In the present
study, the incidence of UATs observed among consecutive
hysterectomy cases was identical to that in uterus-preserving tumor
excision cases. Among the several uterus-preserving tumor excision
procedures, laparoscopically-assisted myomectomy (LAM) is the most
widely accepted by gynecologists, as it allows the excision of
hundreds of nodular lesions from the myometrium of a single
patient. Therefore, we hypothesize that if larger numbers of LAM
cases are accumulated and the nodular lesions excised are
histopathologically examined, large numbers of small-sized UATs may
be incidentally discovered.
The true incidence of UATs may be significantly
higher than mentioned in the presently available literature
(2,4). Further investigations, including
accumulation of hysterectomy as well as LAM cases, are required to
confirm the present results.
References
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