Bowel mesentery (meso-appendix) microcystic/reticular schwannoma: Case report and literature review

Abstract

Microcystic/reticular schwannoma is a recently described variant of schwannoma with a predilection for the gastrointestinal tract. Due to overlapping features with other tumors, unawareness of this tumor type may lead to diagnostic and therapeutic pitfalls. We here report a case of microcystic/reticular schwannoma arising in the meso-appendix of a 43-year-old woman. The tumor was incidentally discovered by computed tomography scan for unrelated reasons. A laparoscopic operation was performed shortly after admission. Histological examination revealed a circumscribed tumor with a striking microcystic and cribriform architecture. Immunohistochemically, the tumor cells were diffusely positive for S100 protein, glial fibrillary acid protein and protein gene product 9.5, which were consistent with a peripheral nerve sheath tumor. The patient remains well with no signs of recurrence at a 10-mo follow-up. To our knowledge, this is the first case of microcystic/reticular schwannoma arising in the meso-appendix. Albeit very rare, microcystic/reticular schwannoma should be included in the differential diagnosis of appendiceal tumors.

Cutaneous microcystic/reticular schwannoma: a poorly recognized entity

“…Microcystic/reticular schwannoma was originally reported by Liegl et al as a distinctive variant of schwannoma showing predilections for the gastrointestinal tract . Nevertheless, similar lesions have infrequently been also reported in the respiratory tract, adrenal gland, deep soft tissue of the face and upper back, cervical spine, parotid gland, pancreas, mesentery and skin . Prior to the present study, only three microcystic/reticular schwannomas occurring in the skin have been described .…”

“…Mitotic activity is generally absent, or very low with less than three mitoses per 50 high‐power fields, while atypical mitoses are uniformly absent . By immunohistochemistry, microcystic/reticular schwannoma shows diffuse and strong S100 and more variable GFAP positivity in Schwann cells . In addition, different amounts of interspersed axons (highlighted by neurofilament) and/or fibroblasts (delineated by CD34) can also be present .…”

“…By immunohistochemistry, microcystic/reticular schwannoma shows diffuse and strong S100 and more variable GFAP positivity in Schwann cells . In addition, different amounts of interspersed axons (highlighted by neurofilament) and/or fibroblasts (delineated by CD34) can also be present . The pathogenesis of microcystic/reticular structures has not been completely elucidated, but they probably represent a degenerative phenomenon …”

Mesenteric schwannoma: a rarity or rising trend?

“…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. It is very difficult to detect preoperatively due to lack of specific radiological characteristics.…”

Schwannoma in the hepatoduodenal ligament: A case report and literature review

“…In the abdominal cavity, the retroperitoneum (6% of primary retroperitoneal tumors)[11] and stomach[12] are the most frequently involved sites. However, schwannomas in the ligaments[13], bowel mesentery[14] and abdominal organs including the gallbladder[15], pancreas[16] and liver[17] are rare. To the best of our knowledge, only three cases of schwannoma in the hepatoduodenal ligament have been reported[6-8].…”