Commonest type of mesentric cyst is
**Core Concept**
Mesenteric cysts are rare, benign or malignant lesions that occur in the mesentery, the peritoneal fold that attaches the intestines to the back of the abdominal wall. The mesentery contains blood vessels, lymphatic vessels, and nerves, and cysts can arise from these structures or from the mesothelial cells that line the mesentery.
**Why the Correct Answer is Right**
The most common type of mesenteric cyst is a **dermoid cyst**, which is a type of mature teratoma. Dermoid cysts arise from the inclusion of ectodermal cells in the mesentery during embryonic development and contain a variety of tissues such as skin, hair, and teeth. They are usually benign and can be surgically resected. The pathogenesis of dermoid cysts involves the abnormal proliferation of ectodermal cells, which can occur due to the abnormal migration of cells during embryonic development.
**Why Each Wrong Option is Incorrect**
**Option A:** **Lymphangioma** is a type of cystic malformation that arises from the lymphatic vessels. While it is a type of mesenteric cyst, it is not the most common type. Lymphangiomas are usually benign and can be surgically resected, but they are less common than dermoid cysts.
**Option B:** **Enteric duplication cyst** is a type of cystic malformation that arises from the intestinal wall. While it is a type of mesenteric cyst, it is not the most common type. Enteric duplication cysts are usually benign and can be surgically resected, but they are less common than dermoid cysts.
**Option C:** **Mature cystic teratoma** is a type of teratoma that contains mature tissues such as skin, hair, and teeth. While it is a type of mesenteric cyst, it is not the most common type. Mature cystic teratomas are usually benign and can be surgically resected, but they are less common than dermoid cysts.
**Clinical Pearl / High-Yield Fact**
Dermoid cysts can occur in any part of the mesentery, but they are most commonly found in the small intestine. They can cause symptoms such as abdominal pain, nausea, and vomiting due to the compression of adjacent structures.
**Correct Answer: D. Dermoid cyst.**