British Journal of Radiology (2005) 78, 755-757
© 2005 British Institute of Radiology
doi: 10.1259/bjr/68622762
MR imaging features of endometriosis at the umbilicus
C M Hartigan, MB BCh, FRCR
and
B J Holloway, MRCP, FRCR
Department of Radiology, The Royal Free Hospital, Pond Street, Hampstead, London NW3 2QG, UK
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Abstract
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The radiological features of extrapelvic endometriosis at the umbilicus with large ovarian endometriomas are described. In this patient, the umbilical lesion appears as hypointense on T1 weighted and T2 weighted MR images. The MR characteristics of endometriosis at the umbilicus are compared with those found within the pelvis.
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Case report
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A 42-year-old female was referred to the surgical outpatients with a 6 month history of a non-tender umbilical lump. An umbilical hernia was considered the likely diagnosis and she was referred for an ultrasound examination. This revealed a hypoechoic mass (3.5 cm x 3.5 cm x 2.1 cm) at the umbilicus which contained vascular channels on colour Doppler evaluation. She was also noted to have two large cystic lesions arising from either ovary. Both contained low level echoes within them. With regard to her reproductive history, she had two uncomplicated vaginal deliveries and no prior gynaecological history. The CA-125 was raised at 433 HU ml–1 (normal range 0–35 HU ml–1).
An MRI of the pelvis (Philips 1.5 Tesla; Philips, Best, The Netherlands) revealed a large, unilocular fluid filled cyst arising from the right ovary which was of high signal on T1 and T2 weighted sequences (Figure 1
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Figure 1. Coronal (a) T1 and (b) T2 weighted turbo spin echo sequence of the abdomen showing a large uniloculated cyst of high signal intensity on both sequences, with a smaller cyst related to the left ovary which is of high signal intensity on T1 weighting but demonstrates shading on the T2 weighted image.
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A second cyst was seen in relation to the left ovary, which was of high signal on T1 weighting but demonstrated shading on T2 weighting (Figure 1
).The umbilical mass appeared as nodular, diffuse circumferential, soft tissue thickening. This was of low signal intensity on T1 and T2 weighted images (Figure 2).
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Figure 2. Sagittal (a) T1 and (b) T2 weighted turbo spin echo images depicting the low signal intensity of the umbilical nodule.
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The patient underwent a laparotomy with hysterectomy and bilateral salpingoophorectomy as well as removal of the umbilicus. The histopathological result revealed bilateral ovarian endometriosis with separate foci of endometrial tissue on the umbilicus (Figure 3). There was no evidence of malignancy. The patient made a complete recovery and was discharged on oral medroxyprogesterone acetate and hormone replacement therapy.
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Figure 3. Histologically proven umbilical endometriosis post surgical excision. (A) Endometrial epithelium. (B) Endometrial stroma containing haemosiderin. (C) Subcutaneous fat of the anterior abdominal wall.
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Discussion
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The differential diagnosis of an umbilical nodule includes metastasis, umbilical hernia, endometriosis, primary carcinoma, granuloma (pyogenic, foreign body) and urachal duct cyst. When due to metastatic malignancy it is eponymously known as a Sister Mary Joseph nodule. The presence of such a nodule has previously been regarded as a sign with a grave prognosis and had implied therapeutic abstention [1, 2]. Sister Mary Joseph was a surgical assistant at the Mayo Clinic who described the periumbilical nodule as a sign of intra-abdominal malignancy [3]. The most common sources in descending frequency are colonic, gastric and ovarian cancer [4].
However, it has recently been demonstrated that most umbilical lesions are benign [1]. It is therefore important to consider all causes, including endometriosis, in patients who present with an umbilical mass.
Endometriosis is one of the most common benign gynaecological conditions and is estimated to be present in between 10% and 25% of women who have undergone diagnostic pelvic laparoscopy [5]. It most commonly affects the ovary, where endometrial cells may enter ovarian stroma resulting in the formation of a "chocolate cyst" or endometrioma. The chocolate coloured fluid is thought to represent debris from cyclical menstruation. Extrapelvic sites can potentially involve any organ system or tissue and are found in 12% of cases. It would appear that the frequency decreases with distance from the uterus and fallopian tubes [6]. The sites at which it is most commonly found in descending order of frequency include ovaries, uterine ligaments, pouch of Douglas, uterine serosal surface, fallopian tubes, rectosigmoid and bladder. In addition to the umbilicus, atypical sites of implantation have been described in the gastrointestinal tract (appendix, caecum, ileum), urinary tract (bladder, ureter), chest (pleura) and even the brain.
MRI is useful in evaluating patients with suspected endometriosis. Endometriomas appear as homogeneously hyperintense on T1 weighted sequences. They often demonstrate shading (i.e. loss of signal within the lesion) which can be seen on T2 weighted images. This shading reflects the chronic nature of an endometrioma and helps differentiate it from other blood-containing lesions [7].
MRI has some advantages over laparoscopy in assessing the extent of endometriosis. These include the evaluation of extraperitoneal disease and lesions concealed by adhesions [5]. It is limited in its ability to detect small implants and therefore cannot replace laparoscopy which remains the gold standard. It is, however, a complementary technique that is useful in helping to establish the extent of disease as well as documenting treatment response [8].
Yu et al described the MRI features of umbilical endometriosis in two patients. In the first case, the lesion was hypointense on T1 weighting with small foci of bright signal (which remained of high signal with fat suppression in keeping with extracellular methaemoglobin). This was predominantly bright on T2 weighting. In the second case, the lesion was hypointense on T1 weighting and of mixed signal on T2 weighting [9]. By contrast, the patient presented in this case report had an umbilical endometriotic implant that was of low signal on both T1 and T2 weighted images. The low signal on T2 weighting is likely to have been due to the presence of haemosiderin which was shown to be present in the excised specimen. This MRI finding is important and should help distinguish an umbilical mass secondary to endometriosis from other more sinister causes.
Received for publication January 9, 2005.
Revision received February 15, 2005.
Accepted for publication February 25, 2005.
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References
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- Shaw RW. Endometriosis. In: Shaw RW, Soutter WP, Stanton SL. Gynaecology (2nd edn). London, UK: Churchill Livingstone, 1997:457–74.
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- Yu C, Perez-Reyes M. MR appearance of umbilical endometriosis. J Comput Assist Tomogr 1994;18:269–71.[Medline]
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