Published online Jan 14, 2018. doi: 10.3748/wjg.v24.i2.303
Peer-review started: August 31, 2017
First decision: September 20, 2017
Revised: October 3, 2017
Accepted: October 26, 2017
Article in press: October 26, 2017
Published online: January 14, 2018
A 58-year-old woman visited our department due to a lesion detected incidentally in her abdominal cavity during a routine health examination in the local hospital.
A lesion, palpable in the her upper left abdomen, was sized 12 cm × 6 cm, and she felt slight tenderness.
Gastrointestinal stromal tumour, intra-abdominal teratoma, sarcoma and neurogenic tumour.
Blood test findings, including tumour markers, were unremarkable.
Ultrasound revealed a solid lesion in the upper left abdomen, with clear margin, and also showed some cystic and strong echo areas in the lesion. Color doppler flow imagings (CDFIs) showed blood signals in the lesion. In a native computed tomography (CT) scan, the lesion in the upper left abdomen appeared well-defined and was 9.6 cm in diameter, while regions of high density were visible, compatible with calcification and/or ossification. Contrast-enhanced CT study revealed a lesion with slight and inhomogeneous enhancement. On T1-weighted images, the upper left abdominal lesion appeared hypointense, while appeared inhomogeneous and hyperintense on T2-weighted images (Figure 2). According to these imaging results, the abdominal lesion was primarily considered to be a teratoma.
Macroscopically, the mass was 10.0 cm × 9.0 cm × 9.0 cm in size and yellowish-white in colour. Microscopically, in the mesenteric tumour, both hypercellular and hypocellular areas were visible. The tumour mainly consisted of spindle-shaped cells with a palisading arrangement; atypical cells or signs of malignancy were not observed. Some areas of the tumour were ossified, and a true metaplastic bone formation could be seen, with the presence of bone lamellae and osteoblasts. Immunohistochemical investigation of the tumour showed a strong positivity for S-100 protein , while SMA, CD34, CD117 and DOG-1 were negative. The cell proliferation index, measured with Ki67 staining, was less than 3%. Finally, a giant benign ossified mesenteric schwannoma was diagnosed.
The authors completely resected the mass located in the mesentery by laparotomy.
Schwannomas in the bowel mesentery are extremely rare. To our knowledge, only 9 cases of schwannomas located in the bowel mesentery have been reported. In addition, mesenteric schwannoma with ossified degeneration has not been reported thus far.
In the present study, the authors present the first giant ossified benign mesenteric schwannoma. It was difficult to obtain an accurate diagnosis of the mesenteric schwannoma preoperatively, because of the lack of specific symptoms, radiological characteristics and tumour markers.