British Journal of Radiology (2008) 81, e4-e6
© 2008 British Institute of Radiology
doi: 10.1259/bjr/22157913
Plicae palmatae of the cervical canal visualized on MRI
A Takahata, MD1,
T Koyama, MD, PhD2,
K Yamada, MD, PhD1,
T Nishimura, MD, PhD1,
S Fujii, MD, PhD and
K Togashi, MD, PhD4
1 Department of Radiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, 2 Department of Radiology, Kyoto University Hospital, and Departments of 3 Gynecology and Obstetrics and, 4 Diagnostic Imaging and Nuclear Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan
Correspondence: Takashi Koyama, Department of Radiology, Kyoto University Hospital, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto, 606–8507, Japan. E-mail: montpeti{at}kuhp.kyoto-u.ac.jp
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Abstract
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We report a case in which plicae palmatae (a normal anatomical structure of the cervix) was demonstrated on MRI. A 33-year-old woman with endometrial cancer underwent a pre-operative MRI examination before total abdominal hysterectomy. Axial T2 weighted images through the cervix demonstrated a longitudinal line of distinct hypointensity confined to the cervical canal. Gross examination of the surgical specimen revealed a relatively large median longitudinal ridge, as well as shorter folds fanning out laterally and upward, which were clearly identifiable on the endocervical wall. The midline longitudinal ridge was considered to represent a portion of the plicae palmatae, which are folds on the anterior and posterior walls of the uterine cervical canal. On MRI, one should avoid misdiagnosing this line of hypointensity as a septate uterus.
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Introduction
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Inherently high tissue contrast on MRI enables detailed visualization of uterine structures. On T2 weighted images, the normal cervix has been known to show distinct zonal anatomy. The central area of the cervical canal exhibits bright signal intensity, representing cervical epithelium and mucin. The inner cervical stroma exhibits low intensity, representing fibrous stroma, whereas the outer cervical stroma shows slightly increased signal intensity, representing loose connective tissue [1].
On T2 weighted images, particularly in the axial plain, longitudinal ridges of low signal intensity are occasionally observed on the anterior and posterior walls of the endocervix. However, to the best of our knowledge, these endocervical ridges and their MRI characteristics have not been previously described in the English literature. We present a case in which T2 weighted images demonstrate a distinct linear structure of low intensity at the midline of the endocervix; this directly correlated with the gross findings of the resected uterus. The anatomical and embryological backgrounds of the ridges will be briefly reviewed.
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Case report
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A 33-year-old woman (gravida 0, para 0) presented with abnormal genital bleeding. Endometrial biopsy revealed endometrial cancer. She underwent a pre-operative MRI examination, which revealed an ill-defined endometrial tumour of intermediate signal intensity on sagittal T2 weighted images. On axial T2 weighted images through the cervix, a longitudinal line of distinct low intensity was demonstrated within the cervical canal (Figure 1
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Figure 1. AxialT2 weighted fast spin-echo image (repetition time/echo time = 5000/87) demonstrates a line of low intensity at the midline of the endocervix (arrow).
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Total hysterectomy was performed for endometrial cancer. The gross specimen of the resected uterus, opened through the midline of the anterior wall, contained endometrial tumour protruding into the lumen from the fundus, but no apparent uterine anomaly. On the posterior wall of the endocervix, a median longitudinal ridge and shorter folds fanning out laterally and upward, which represent the plicae palmatae, were clearly identifiable (Figure 2).
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Figure 2. Gross photograph of the uterus after formalin fixation demonstrates a longitudinal ridge at the midline of the posterior cervical wall(arrows). At the fundus of the uterine corpus, endometrial cancer can be recognized as a lesion protruding into the uterine cavity (arrowheads).
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Discussion
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The plicae palmatae are a system of folds on the anterior and posterior walls of the cervical canal, consisting of median longitudinal ridges and many shorter elevations extending laterally and upward (Figure 3) [2]. The numerous oblique folds on the walls are not directly opposed in the anteroposterior directions; rather they fit between one another like a zipper, thus maintaining the integrity of the cervical canal. The median longitudinal ridges are more evident than the other oblique folds, and are considered to represent the remnant of fusion of the Müllerian ducts [2]. Inasmuch as the longitudinal ridges are located at the midline of the anterior and posterior walls of the cervical canal, it is reasonable to hypothesize that these ridges might be related to the process of fusion of the Müllerian ducts.
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Figure 3. Schematic line diagram of the plicae palmatae in the uterus. Branching lines in the cervical canal represent plicae palmatae, which consist of a median longitudinal ridge and shorter folds fanning out laterally and upward.
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In the presented case, the longitudinal line of low intensity that was limited to the cervix when viewed on T2 weighted MRI correlated to the gross pathological finding of longitudinal ridges at the posterior wall of the cervical canal. Histological evaluation failed to demonstrate any difference between the midline ridge and other parts of the cervical epithelium that could explain the variation in signal intensity on T2 weighted images.
The central bright intensity of the cervix on T2 weighted images represents epithelium and mucus [1]. Although it is still unclear why the longitudinal ridge shows low intensity, we speculated that this finding is because the longitudinal ridges lack the space to contain mucus and fluid, whereas the other small oblique columns have many clefts to contain such fluids.
On T2 weighted images, this line of low intensity at the endocervix could resemble the anomalous fibrous septum of a septate uterus [3]. However, a longitudinal ridge limited to the cervix does not fulfil the criteria of a septate uterus. Septate uterus has a septum that projects from the fundus and extends the entire length of the uterine cavity [4]. One must take care not to misdiagnose these plicae palmatae as a uterine septum, which can frequently cause repetitive abortion or infertility and may require surgical removal.
The present case indicates that longitudinal ridges limited to the cervix may be observed in an otherwise normal cervix. In MRI evaluation of young patients presenting with repeated abortions and/or infertility, one should be careful not to mistake this line of low intensity as a septate uterus.
Received for publication January 12, 2006.
Revision received October 26, 2006.
Accepted for publication October 30, 2006.
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References
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- Scoutt LM, McCauley TR, Flynn SD, Luthringer DJ, McCarthy SM. Zonal anatomy of the cervix: correlation of MR imaging and histologic examination of hysterectomy specimens. Radiology 1993;186:159–62.[Abstract/Free Full Text]
- Kistner RW. Gynecology Principles and Practice. Chicago, IL: Year Book Medical Publishers; 1980.
- Scarsbrook AF, Moore NR. MRI appearances of mullerian duct abnormalities. Clin Radiol 2003;58:747–54.[CrossRef][Medline]
- The American Fertility Society. Classifications of adnexal adhesions, distal tubal occlusion, tubal occlusion secondary to tubal ligation, tubal pregnancies, mullerian anomalies and intrauterine adhesions. Fertil Steril 1988;49:944–55.[Medline]
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Abstract
Introduction
