A schwannoma of the cecum: Case report and review of Japanese schwannomas in the large intestine

Abstract

A 66-year-old Japanese man had a positive fecal occult blood test at a regular check-up, and a large polypoid mass was detected in the cecum by barium enema study. Colonoscopy showed a submucosal tumor with ulcer protruding into the cecal lumen. A large-forceps biopsy specimen was taken from the bottom of the ulcer. With the tentative diagnosis of neurogenic tumor, ileocecal resection was performed. The tumor showed spindle-cell proliferation in a concentric or fascicular pattern. Immunohistochemically, the tumor cells were diffusely positive for S-100 protein, and they had intracytoplasmic periodic acid Schiff (PAS)-positive crystalloids. The mitosis count was low (about 1 per 20 high-power fields). The pathological diagnosis of this tumor was benign gastrointestinal schwannoma. A large number of schwannoma cases have been reported since 1910 when Verocay reported it as a true tumor that stemmed from Schwann cells and did not contain neuroganglion cells. However, gastrointestinal schwannomas are rare, and schwannomas of the large intestine are extremely rare. We reviewed 40 cases already reported in Japan and this present case in order to clarify the clinicopathological features of this tumor.

Evaluation of NF2 and NF1 Tumor Suppressor Genes in Distinctive Gastrointestinal Nerve Sheath Tumors Traditionally Diagnosed as Benign Schwannomas: A Study of 20 Cases

“…Discussion GI schwannomas are rare peripheral nerve sheath tumors that show a distinctive set of histologic features that differ from conventional central nervous system and peripheral, soft tissue schwannomas. These distinctive features include a peripheral lymphoid cuff, common microtrabecular pattern, and lack of nuclear palisading and xanthoma cells (Daimaru et al, 1988;Hirose et al, 1997;Miettinen et al, 2001;Prévot et al, 1999;Sarlomo-Rikala and Miettinen, 1995;Sasatomi et al, 2000;Scheithauer et al, 1999;Skopelitou et al, 1998;Tomozawa et al, 1998;Yagihashi et al, 1997). In this study, we evaluated NF2 and NF1 alterations in 20 well-documented GI schwannomas using archival formaldehyde-fixed, paraffinembedded (FFPE) material.…”

“…The tumor cells are positive for S-100 protein and glial fibrillary acidic protein (GFAP) and negative for desmin and ␣-smooth muscle actin (SMA), unlike true leiomyomas, and negative for KIT (CD117) and CD34, unlike GI stromal tumors. All tumors with such phenotypic features reported thus far have followed a benign clinical course (Daimaru et al, 1988;Hirose et al, 1997;Miettinen et al, 2001;Prévot et al, 1999;Sarlomo-Rikala and Miettinen, 1995;Sasatomi et al, 2000;Skopelitou et al, 1998;Tomozawa et al, 1998;Yagihashi et al, 1997).…”

“…The tumor cells are positive for S-100 protein and glial fibrillary acidic protein (GFAP) and negative for desmin and ␣-smooth muscle actin (SMA), unlike true leiomyomas, and negative for KIT (CD117) and CD34, unlike GI stromal tumors. All tumors with such phenotypic features reported thus far have followed a benign clinical course (Daimaru et al, 1988;Hirose et al, 1997;Miettinen et al, 2001;Prévot et al, 1999;Sarlomo-Rikala and Miettinen, 1995;Sasatomi et al, 2000;Skopelitou et al, 1998;Tomozawa et al, 1998;Yagihashi et al, 1997).Neurofibromatosis 2 (NF2) is an autosomal dominant disorder caused by genetic alterations of the NF2 tumor suppressor gene (Gutmann, 1997 1361 mapped to 22q12 and encodes for a protein designated as merlin or schwannomin (Hovens and Kaye, 2001;Rouleau et al, 1993;Trofatter et al, 1993). Bilateral vestibular schwannomas are a typical diagnostic feature of NF2.…”

Isolated Colonic Schwannoma in the Ascending Colon: A Case Report and Literature Review of Schwannomas in the Large Intestine

“…According to a previous review of colonic schwannomas in Japan, only 4 of 41 cases (10%) were correctly diagnosed as schwannoma preoperatively (6). Preoperative imaging can be helpful to define the exact tumor location and obtain information about the tumor.…”

“…It has been reported that perilesional lymphadenopathy are more often observed in gastric schwannomas than in gastric GIST (7). Although it is not certain, these lymph nodes are presumed to be reactive hyperplasia due to the fact that There are fourteen case reports of colonic schwannomas written in English or Korean and these reports provide accessible information about imaging findings (6,(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19). We reviewed these cases as well as ours ( Table 1).…”