A Case of Human Epidermal Growth Factor Receptor 2-Positive Colon Cancer With Invasive Micropapillary Carcinoma...

Area of Science:

• Gastroenterology
• Oncology
• Endoscopic Imaging

Background:

• Invasive micropapillary carcinoma (IMPC) is a rare subtype of adenocarcinoma.
• IMPC is associated with a high rate of lymph-node metastasis and poor prognosis in various cancers.
• Early endoscopic detection of IMPC in colon cancer is challenging.

Purpose of the Study:

• To report the first case of cancerous IMPC component identified by magnifying endoscopy at T1b (submucosal) depth.
• To emphasize the importance of considering IMPC in differential diagnoses for colon lesions with suspicious endoscopic findings.
• To review the literature on IMPC in gastrointestinal cancers.

Main Methods:

• A 60-year-old female patient underwent screening fecal occult blood test.
• Colonoscopy with narrow-band imaging, ultra-magnification, and endoscopic ultrasonography was performed.
• Endoscopic submucosal dissection followed by additional surgery was conducted.

Main Results:

• Colonoscopy revealed a 15-mm flat elevated lesion with central depression in the sigmoid colon.
• Magnifying endoscopy and pit pattern analysis suggested malignancy (JNET 2B, Type VI pit, EC3a morphology).
• Pathology confirmed moderately differentiated tubular adenocarcinoma with IMPC and deep submucosal invasion (T1b SM).

Conclusions:

• This case demonstrates the successful identification of IMPC by magnifying endoscopy at T1b (SM) depth.
• IMPC should be considered in the differential diagnosis of intermediate-sized colon lesions with concerning endoscopic features.
• Prompt diagnosis and appropriate treatment, including surgery, are vital for managing IMPC and preventing recurrence.