Keywords
intrauterine mass - placenta - deciduoma - ectopic uterine tissue
Deciduosis is the presence of ectopic decidual tissue in locations outside the uterus.
This is a phenomenon first described in 1887 by Walker.[1] Deciduosis has been reported to occur in various pelvic and abdominal organs.[2] Although international literature has only a few case reports published on ectopic
deciduosis, the condition is more frequent than initially believed. Deciduosis is
usually asymptomatic and can remain undetected throughout pregnancy.[2] Based on a recent report, the condition was present in 10% of patients that underwent
Cesarean section.[2] Typically, deciduosis occurs during pregnancy but has been reported in nonpregnant
women as well. In the absence of pregnancy, ectopic decidual changes are caused by
progesterone released by the corpus luteum.[3] During pregnancy, it is considered to be a benign lesion, not associated with any
obstetric complications, and does not have any pathological impact during pregnancy.
Total remission occurs in the postpartum period.[2] Intrauterine deciduosis has not been previously reported. We described a case of
a large vascular intrauterine mass initially suspected to be a malignant tumor, which
regressed during the pregnancy, and was subsequently diagnosed as deciduosis.
Case Report
A 28-year-old female, G1 P0 was referred at 14 4/7 weeks for reasons of abnormal twin gestation with early onset oligohydramnios. The
referral document indicated a hydropic structure with cardiac activity and a normal
second fetus with a heart rate of 145 bpm. The hydropic structure was identified as
having prominent vessels and no extremities, and referred with diagnosis of suspected
acardiac twin. The patient had no history of spotting, bleeding, discomfort, chronic
headaches, or respiratory symptoms at the time of referral.
In our assessment the pregnancy was a singleton at 14 4/7 weeks with a large vascular mass protruding into the lower uterine cavity, arising
from the cervicouterine area ([Figs. 1] and [2]). There was a small amount of fluid around the mass. The pulse rate in the blood
vessels within the mass was similar to the maternal heart rate. The singleton fetus
appeared normal with normal growth. The differential diagnosis included a pedunculated
fibroid, a large vascular polyp, or a malignant growth. The patient was counseled
regarding the possible causes and options, and that if the mass was suspected to be
malignant on further workup she would have the option of pregnancy termination. The
patient declined to pregnancy termination irrespective of the diagnosis. A magnetic
resonance imaging (MRI) was ordered, and the patient was subsequently referred for
a consultation with the gynecologic services for assessment of the tumor.
Fig. 1 Increased vascularity within the Intrauterine Mass at 14 4/7 weeks' gestation.
Fig. 2 Intrauterine mass surrounded by fluid, at 14 4/7 weeks' gestation.
An MRI at 18 5/7 weeks reported a soft tissue mass of 1.6 × 2.0 × 4.9 cm, eccentric and crescentic
shaped with differential diagnosis of a “Stuck Twin syndrome” with demise of the presenting
stuck twin. At 19 3/7 weeks, on a repeat obstetrical ultrasound, the fluid surrounding the mass and the
vascularity were significantly reduced. The mass continued to have minimal arterial
circulation with a pulse rate consistent with the maternal heart rate.
Ultrasound examinations were initially repeated every month. At 21 3/7 weeks, the mass stayed stable in size, measuring 4.36 × 2.00 × 3.26 cm and, at 25
3/7 weeks, it was essentially unchanged measuring 4.7 × 2.6 × 1.8 cm. Due to the stable
size of the mass, as well as significantly reduced vascularity, the patient was reexamined
at 33 5/7 weeks and the mass had reduced in size measuring 3.6 × 2.2 × 3 cm. Over time, the
vascularity was documented to decrease with minimal blood flow. The mass stayed adherent
to the lower portion of the posterior uterine wall.
At 39 4/7 weeks, the patient experienced spontaneous labor and underwent a normal vaginal delivery.
Following the delivery of the baby, the uterine cavity was explored and, with complete
ease, the mass was manually extracted in full, with no additional blood loss. It was
a smooth soft spongy mass with no raw edges ([Fig. 3]). On pathology, the mass measured 7.5 × 4.7 × 2.6 cm and was described as an ovoid,
membranous, dark red, soft tissue with a hemorrhagic surface. On the final histopathologic
diagnosis, the mass was reported as deciduosis ([Fig. 4]). Three weeks after delivery a postpartum ultrasound was performed which was normal.
Findings indicated anteverted normal appearing midline uterus and cervix. Endometrial
stripe was normal. Ovaries were normal bilaterally with no cysts or masses. There
was no evidence of the previously observed lower uterine mass.
Fig. 3 Mass extracted during delivery, measured 7.5 × 4.7 × 2.6 cm.
Fig. 4 Histopathology of the intrauterine mass.
Discussion
Ectopic deciduosis has been defined as decidual tissue found in an extrauterine location
during a pregnancy. There are various theories on the pathogenesis of deciduosis.
It has been suggested that progesterone can induce ectopic decidua, a reversible phenomenon.[6]
[7] In association with pregnancy, the ectopic decidual cells have been reported in
the fallopian tube, ovaries, uterine serosa, cervix, and vagina, as well as outside
the genital tract including the peritoneum, omentum, appendix, and lymph nodes but
not intrauterine.[4]
[7] The lesions are described as white nodules less than 1 cm in diameter that may coalesce
or be isolated.[7] Ectopic decidua is usually an incidental finding, detected during surgical procedures,
which include Cesarean sections, postpartum tubal ligations, and appendectomies.[7] Typically asymptomatic, deciduosis can present with clinical symptoms of shortness
of breath, hemoptysis, pneumothorax, progressive anemia, pelvic pain, and risk of
infections depending on the site. Rarely, complications, such as massive intra-abdominal
bleeding have been reported.[5]
Though the lesions are typically described in mm, larger lesions in the cervix and
the omentum have been reported. The cervical lesions have been described as large
masses with the largest reported being 8 cm.[4] In the omentum, the lesions can be large as well. When the mass is large, it is
frequently mistaken for malignancy and requires histopathology for final diagnosis.[2]
[4] Omental and peritoneal lesions are more common and with increasing duration of pregnancy
regressive changes have been reported.[8]
To our knowledge, there are no reported cases of intrauterine deciduosis during the
course of a normal pregnancy. In our case, we had the advantage of following the lesion
longitudinally from the end of the first trimester until delivery at term. To our
surprise, the vascularity, as well as the size of the mass, was seen to reduce remarkably
by the third trimester, making it highly unlikely that we were dealing with a malignant
tumor. At delivery we were prepared for an adherent mass and postpartum hemorrhage.
However, the entire mass was easily extracted manually, without any complications.
Fortunately, in our case, in spite of the lesion being large, the patient did not
experience any episode of heavy bleeding antenatally or during the time of delivery.
Perhaps, since the vascularity regressed overtime, the delivery was uncomplicated.
Conclusion
In conclusion, based on our case and those reported in the literature, we believe
that there are two separate entities of ectopic deciduosis, diffuse deciduosis with
smaller lesions and the larger vascular mass lesions. We propose to classify ectopic
deciduosis into two categories, as benign diffuse ectopic deciduosis which is typically
asymptomatic, and a deciduoma which is a large vascular lesion with potential for
hemorrhage. By categorizing the larger vascular lesions as deciduoma, the lesion may
be accurately diagnosed prenatally more frequently, and it could help the obstetrician
prepare for the possible hemorrhagic complications. It would also guide the obstetrician
in continuing with expectant management, with the hope of reduction in vascularity
and size of the lesion as the pregnancy progresses.
