large bowel leiomyoma

Based on the context provided, here's a description of large bowel (colon) leiomyoma:

A large bowel leiomyoma, also known as colonic leiomyoma, is a rare and benign tumor that arises from the smooth muscle cells in the wall of the colon. It is a type of leiomyoma, which is a non-cancerous growth made up mostly of smooth muscle cells.

Characteristics of large bowel leiomyoma:

• Typically occurs in elderly individuals
• Can be found in any part of the colon, but most commonly in the transverse colon
• Usually presents as a single, well-circumscribed lesion
• May cause symptoms such as abdominal pain, constipation, bleeding, or luminal obstruction if it grows too large or develops in specific locations
• Larger tumors (larger than 2cm) are more likely to cause bulk-related symptoms, altered bowel habits, a palpable abdominal mass, and/or bloody stools
• Can be found incidentally during an upper gastrointestinal (GI) endoscopy or colonoscopy for another reason

Histologically, colonic leiomyomas are well-circumscribed lesions that arise from the muscularis mucosae and occupy the submucosa. They may have a characteristic "network" of connective tissue and well-developed smooth muscle extending into the polyp.

It's worth noting that while large bowel leiomyoma is benign, it can mimic more aggressive tumors on imaging studies, such as gastrointestinal stromal tumor (GIST).

Based on the provided context, here are some signs and symptoms associated with large bowel (colonic) leiomyomas:

1. Abdominal pain: This is a common symptom, especially for larger tumors.
2. Constipation: Large leiomyomas can cause bulk-related symptoms, including altered bowel habits.
3. Bleeding: Rectal bleeding or hematochezia may occur, especially if the tumor erodes into the lumen of the colon.
4. Luminal obstruction: Larger leiomyomas can cause intestinal obstruction, leading to vomiting, diarrhea, and weight loss.
5. Palpable abdominal mass: A large leiomyoma can be felt as a lump in the abdomen.
6. Tenesmus: This is a feeling of needing to have a bowel movement, even after passing stool.
7. Dyschezia: Difficulty passing stool or having a bowel movement.
8. Vomiting and diarrhea: These symptoms may occur due to intestinal obstruction.

It's worth noting that not all large bowel leiomyomas cause symptoms, and some may be found incidentally during imaging studies or surgical procedures. However, when symptoms do occur, they can range from mild discomfort to life-threatening complications like perforation.

Differential Diagnosis of Large Bowel Leiomyoma

Large bowel leiomyomas are rare tumors that can be challenging to diagnose, especially when they present with symptoms similar to other gastrointestinal conditions. The differential diagnosis for large bowel leiomyoma includes:

• Gastrointestinal Stromal Tumor (GIST): A type of tumor that arises from the interstitial cells of Cajal in the gastrointestinal tract. GISTs can be benign or malignant and are often positive for CD117 immunohistochemistry [5].
• Malignant Leiomyosarcoma: A rare and aggressive form of cancer that originates from smooth muscle cells in the gastrointestinal tract. The distinction between leiomyoma and leiomyosarcoma is crucial, as it affects treatment and prognosis [8].
• Other Mesenchymal Tumors: Such as schwannomas, neurofibromas, and fibromas, which can also present with similar symptoms to leiomyomas.

Key Features for Differential Diagnosis

To differentiate large bowel leiomyoma from other conditions, the following features are important:

• Immunohistochemistry: The presence or absence of specific markers such as CD117, S100, and smooth muscle actin can help distinguish between leiomyoma and GIST [5].
• Histological Features: The microscopic appearance of the tumor, including its cellular composition, nuclear morphology, and mitotic activity, is essential for diagnosing leiomyosarcoma [8].
• Clinical Presentation: Symptoms such as abdominal pain, intestinal obstruction, and perforation can be present in both leiomyoma and GIST, but the presence of a palpable abdominal mass may suggest leiomyoma [3].

References

[5] Mod Pathol 2015 - This study highlights the importance of CD117 immunohistochemistry in differentiating GIST from other mesenchymal tumors.

[8] by NH Dreifuss · 2021 · Cited by 1 - This article emphasizes the need for careful histological examination to distinguish leiomyoma from leiomyosarcoma.