Gastrointestinal tract-like muscular walls in ovarian mature cystic teratomas: A histopathological study.

To elucidate the frequency and histopathological features of gastrointestinal (GI) tract-like muscular walls developing in ovarian mature cystic teratoma (MCT), the present study examined 149 MCTs surgically removed from 126 females, including 23 bilateral cases. GI tract-like muscular walls were identified in 9 (7.1%) cases, and were accompanied by mucosa in 5 cases, muscularis mucosae in 5 cases, serosa in 5 cases and all of these components in 3 cases. The mean size of the GI tract-like structures was 0.6 cm. The presence of MCT-related GI tract-like muscular walls was not significantly associated with patient age, size of MCTs or bilateral presence of MCT. The detected mucosae and muscular walls commonly demonstrated incomplete or anomalous features. Immunohistochemically, a few weakly KIT+ spindle and/or stellate cells were identified in 7 cases (77.8% of the 9 cases of MCT-related GI tracts); these cells were presented chiefly near conspicuous or inconspicuous S-100 protein+ neural tissues between the conspicuous or inconspicuous two muscular wall layers, indicating interstitial cells of Cajal (ICCs). Discovered on gastrointestinal stromal tumors 1 co-expression in KIT+ ICCs was observed in only 1 case. Neural cell-related intramuscular cluster of differentiation 34+ cells were occasionally observed; however, no hyperplastic ICCs were observed in the present study.