Radiological appearance of primary extracranial meningioma of the pelvis in a middle-aged woman

Abstract

DesCripTionA 47-year-old woman came with the complaints of on-and-off constipation for 6 months with the inability to pass stool for 2 days. She also complained of poor urinary stream and increased urine frequency for 1 year and had a history of hysterectomy with bilateral salpingo-oophorectomy. Her general and systemic examinations were unremarkable. Abdominal radiograph revealed diffuse opacification of the pelvis with left lateral displacement and compression of the rectal shadow ( figure 1A). CT of abdomen and pelvis (figure 1B-F) revealed a large, well-defined heterogeneously enhancing lobulated lesion in the presacral region and central pelvis showing multiple coarse calcifications within. The lesion was abutting the distal sigmoid colon and rectum causing their left lateral displacement with luminal compression and loss of intervening fat plane. There was resultant dilatation of the large and distal small bowel loops suggestive of intestinal obstruction. The fat plane between the lesion and the urinary bladder was also lost suggestive of adherence or infiltration. No direct endoluminal invasion into the bowel or bladder was seen. The patient further underwent MRI of the lumbosacral spine to rule out neurogenic cause for her symptoms. On MRI ( figure 1G-I), the visualised portion of the pelvic lesion was heterogeneous with peripheral enhancing solid areas and central large non-enhancing necrotic area. The solid areas were isointense on T1 sequence and hyperintense on the T2 sequence. No abnormality of the conus medullaris or nerve root compression was detected. The imaging differentials that we considered were neurogenic tumour, gastrointestinal stromal tumour (GIST) and soft-tissue sarcoma. A neurogenic tumour could explain all the imaging features. GIST and sarcomatous lesion also would have most of these imaging features except for the presence of multiple calcifications, which is a relatively uncommon feature in them.The patient was taken up for laparotomy and tumour excision under spinal anaesthesia. However, due to adhesion of the lesion to colon and the bladder, only debulking of the lesion was performed. Histopathological examination (figure 2) revealed typical whorls of meningothelial epithelioid cells, which were reactive to epithelial membranous antigen on immunohistochemistry suggestive of meningothelial meningioma (WHO grade I).The extracranial meningiomas are rare tumours most commonly occurring in the head and neck region (0.9% to 2% incidence) with their occurrence in pelvis being even more rarer. The prefix 'primary' indicates that the lesion has no connection to the central nervous system and the theories to explain their origin include misplaced extradural arachnoid cell during embryogenesis, ectopic embryonic arachnoid cells rest growth, arachnoid cells rest migration along the nerve sheaths of cranial nerve or differentiation from perineural cells.

Extra-cranial meningioma associated with relapse of immature ovarian teratoma

“…The most frequent site for primitive extra-cranial meningiomas is the head and neck region, but anecdotal case reports also described primitive extra-cranial meningioma localization in the pelvis. [14][15][16] In the cases previously described in literature, the patients had a history of hysterectomy with bilateral salpingo-oophorectomy. Theories proposed to explain these unusual locations include the migration of arachnoid cells rests along cranial nerve sheaths, the proliferation of extra-dural arachnoid cells, or the growth of ectopic embryonic rests of arachnoid cells.…”

Primary extracranial meningioma of the pelvis discovered on screening pelvic examination

“…Our patient presented to an annual well-woman visit with no evident symptoms and was discovered to have a pelvic mass on screening bimanual pelvic examination. We are aware of only two other reported cases of pelvic meningiomas, both occurring in postmenopausal females 18 19. In each case, the patients had previously undergone hysterectomy with bilateral salpingo-oophorectomy.…”