Successful treatment of a giant ossified benign mesenteric schwannoma

Abstract

Primary benign schwannoma of the mesentery is extremely rare. To date, only 9 cases have been reported in the English literature, while mesenteric schwannoma with ossified degeneration has not been reported thus far. In the present study, we present the first giant ossified benign mesenteric schwannoma in a 58-year-old female. Ultrasound, computed tomography and magnetic resonance imaging were used, but it was still difficult to determine the definitive location and diagnose the mass. By laparotomy, a 10.0 cm × 9.0 cm × 9.0 cm giant mass was found in the mesentery and was then completely resected. Microscopically, the tumour located in the mesentery mainly consisted of spindle-shaped cells with a palisading arrangement. Some areas of the tumour were ossified, and a true metaplastic bone formation was observed, with the presence of bone lamellae and osteoblasts. Immunohistochemical investigation of the tumour located in the mesentery showed that the staining for the S-100 protein was strongly positive, while the stainings of SMA, CD34, CD117 and DOG-1 were negative. The cell proliferation index, measured with Ki67 staining, was less than 3%. Finally, a giant ossified benign mesenteric schwannoma was diagnosed. After surgery, the patient was followed up for a period of 43 mo, during which she remained well, with no evidence of tumour recurrence.

Calcification and ossification in conventional schwannoma: A clinicopathologic study of 32 cases

“…The first case documenting calcification in schwannomas was published in 1961 by Lombardi and Passerini who described calcifications in spinal tumors radiologically detected . In the interim, only single case reports and rare small series have documented dystrophic and/or psammomatous calcification or ossification in schwannomas . Furthermore, the two series available describe two cases each and are limited to vestibular schwannomas .…”

“…We identified ossification in nine schwannomas in our study. Ossification in schwannomas is less common than calcification with only seven prior cases documented in the literature to the best of our knowledge . Consequently, the presence of ossification may lead to the consideration of other mesenchymal tumors that may form bone including ossifying fibromyxoid tumor (OFMT) and extraskeletal osteosarcoma.…”

“…Ossification in schwannomas is less common than calcification with only seven prior cases documented in the literature to the best of our knowledge. 5,10,14,21,29,32 Consequently, the presence of ossification may lead to the consideration of other mesenchymal tumors that may form bone including ossifying fibromyxoid tumor (OFMT) and extraskeletal osteosarcoma. While the former may show limited S-100 protein expression, the bone present in OFMT usually manifests as a peripheral shell.…”

Mesenteric schwannoma: a rarity or rising trend?

“…5,7-10 Secondary degenerative changes like cyst formation, hemorrhage, calcification, hyalinization and rarely ossified degeneration are seen sometimes. 3 Mesenteric schwannoma is extremely rare entity with approximately 10 documented cases till 2018. 3,8,[11][12][13][14][15][16][17][18] These are usually detected incidentally or with vague nonspecific abdominal symptoms such as chronic pain.…”

“…The exact mechanism of tumorigenesis and role of Merlin is poorly understood. 3 Schwannomas are usually found in head, neck, extremities, mediastinum and retroperitoneum. Intrabdominal schwannoma are very rare and occurs most commonly in alimentary tract.…”