Recently while performing a tubal ligation, we noted that the patient had a dilated fallopian tube. During surgery, our differential
diagnosis included chronic ectopic pregnancy, hydro- or pyosalpinx, complex cyst, and tumor. But the pathology report showed
that the dilation was caused by a placental site nodule. Such nodules usually are incidental findings in uterine curettings,
cervical biopsies, or some hysterectomy specimens because they do not produce symptoms and there are no lab studies on which
to base a diagnosis. While some cases require follow up, others do not.
Details of the case Our patient was a 29-year-old gravida 5, para 2 who was using depot medroxyprogesterone acetate for contraception at the time
she was scheduled for bilateral tubal ligation. She was healthy with no complaints and had been a heavy smoker. She'd had
one full-term spontaneous vaginal delivery, followed by a primary cesarean delivery at term, necessitated by preeclampsia,
and a VBAC at 36 weeks. The patient had a history of three D&Cs; two for spontaneous abortions in the first trimester and
one for therapeutic abortion. She began menstruating at age 10 and she had a history of regular cycles until the injectable
contraceptive made her amenorrheic. She had no reported history of sexually transmitted diseases and had a normal abdominal,
pelvic, and rectal examination. Laboratory data were unremarkable, including negative qualitative human chorionic gonadotropin
assay and cervical cultures, normal Pap, and normal white blood count.
The patient underwent bilateral partial salpingectomy via mini-laparotomy. At surgery, we saw a normal left fallopian tube
and ovary with very few thin adhesions, which were easily ligated. Approximately 1.5 cm of the right fallopian tube, at the
midpoint, was distended. Its tan color and fusiform shape made it look like a small ectopic pregnancy. Most of the tube, including
the dilated segment, was resected. The tubal content was light chocolate-brown in color, like a hematosalpinx. The pathology
report showed a normal left fallopian tube and a peritubal placental site nodule in the right fallopian tube.
FIGURE 1. Placental site nodule in the fallopian tube. Small, well-circumscribed nodular aggregates of chorionic-type intermediate-type
cells are surrounded by a thin rim of chronic inflammatory cells and occasionally decidual cells, embedded in a hyalinized
stroma. (Hematoxylin and eosin, original magnification, x10.)
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Recognizing a placental site nodule Placental site nodules are considered a form of gestational trophoblastic disease (GTD), which is a group of lesions derived
from the conceptus and not from the patient. GTDs include molar and non-molar lesions. Placental site nodules are non-molar,
derived from villous intermediate trophoblasts.1On histology, the nodules contain small, haphazardly arranged trophoblastic cells; some of the cells have clear cytoplasm
and others have eosinophilic cytoplasm (Figure 1).2,3 Nodules that are grossly visible usually are well-circumscribed, yellow excrescences confined to the endometrium, endocervix,
or—as in our case—to the fallopian tube. They can range in size from 1 to 14 mm (average 2.1) and in occasional cases there
is more than one.4
As benign lesions, placental site nodules do not invade the endomyometrium or blood vessels. They can, however, develop into
epithelioid trophoblastic tumors, but research thus far shows that to be rare. There are also no documented cases of recurrence
of such nodules, or of associated epithelioid trophoblastic tumors.3
Like our patient, many women with placental site nodule are of reproductive age with a history of pregnancies, therapeutic
abortions, and C/S; a significant number also have a history of tubal ligation.4 At the time of diagnosis, most patients are not pregnant. It's not clear whether a placental site nodule is derived from
the persistence of trophoblast associated with a pregnancy that preceded a tubal ligation or from a new gestation that follows
an unsuccessful tubal ligation.4 It may be a remnant of the placental site that failed to completely involute or arise de novo from an abnormal "blighted"
gestation that never fully developed.1,3 Placental site nodules are distinguished from trophoblastic tumors by their small size, superficial location, circumscription,
extensive hyalinization, and rare-to-absent mitotic activity. The tumors typically are diagnosed in patients who are clinically
thought to have had a missed abortion. It's important to distinguish between the two lesions because there is evidence that
a placental site trophoblastic tumor has malignant potential.2
No specific treatment or follow-up is necessary for placental site nodule since the condition has neither been shown to recur
locally nor to progress to persistent GTD.1 However, the next time you encounter a fallopian tube lesion, consider including placental tube nodule in your differential
diagnosis.
REFERENCES
1. Shih IM, Kurman RJ. Molecular basis of gestational trophoblastic diseases. Curr Mol Med. 2002;2:1-12.
2. Santos LD, Fernando SS, Yong JL, et al. Placental site nodules and plaques: a clinicopathological and immunohistochemical
study of 25 cases with ultrastructural findings. Pathology. 1999;31:328-336.
3. Shih IM, Seidman JD, Kurman RJ. Placental site nodule and characterization of distinctive types of intermediate trophoblast.
Hum Pathol. 1999;30:687-694.
4. Shih IM, Kurman RJ. The pathology of intermediate trophoblastic tumors and tumor-like lesions. Int J Gynecol Pathol. 2001;20:31-47.
CLINICIAN to CLINICIAN offers the hard-won wisdom and expertise of physicians "in the trenches." We're looking for unusual case reports, anecdotes
about innovative treatments, and practical solutions for professional problems from community physicians. Send your submission
of 750 words or less to Editor in Chief Charles J. Lockwood, MD, by e-mail Dr.Lockwood@advanstar.com
, fax (973-847-5340) or mail (5 Paragon Drive, Montvale, NJ 07645). All submissions are subject to peer review by theContemporary OB/GYN Editorial Board. Nevertheless, the concepts discussed may be anecdotal in nature.
