Histopathological and genetic differences between polypoid and non-polypoid submucosal colorectal carcinoma

Area of Science:

• Gastroenterology
• Oncology
• Molecular Pathology

Background:

• Colorectal carcinoma (CRC) exhibits diverse growth patterns, influencing its clinical behavior.
• Understanding histopathological and genetic distinctions between polypoid growth (PG) and non-polypoid growth (NPG) submucosal invasive CRC is crucial for prognosis.

Purpose of the Study:

• To delineate the histopathological and genetic differences between PG and NPG submucosal invasive CRC.
• To compare lesion size, dysplasia grade, invasion depth, lymph node metastasis, p53 expression, and K-ras mutations between PG and NPG CRC.

Main Methods:

• 96 cases of submucosal CRC were classified into PG (60 cases) and NPG (36 cases).
• Histopathological features (size, dysplasia, invasion depth, lymph node metastasis) were analyzed.
• Immunohistochemistry for p53 and polymerase chain reaction for K-ras gene mutations were performed.

Main Results:

• NPG lesions were smaller (7.5 mm vs 13.8 mm) but showed more severe dysplasia.
• NPG CRC had significantly higher rates of submucosal massive invasion (64.3% vs 43.3%) and lymph node metastasis (43% vs 7%).
• K-ras mutations were frequent in PG (67%) but absent in NPG; p53 expression showed no difference.

Conclusions:

• NPG submucosal CRC is characterized by more aggressive histopathological features, including increased invasion and metastasis.
• NPG CRC exhibits a distinct genetic profile with a notable lack of K-ras mutations compared to PG CRC.