Reply to the Letter of Orlowska et al.

Intravital staining in combination with high-resolution or magnification endoscopy allows more detailed evaluation of the mucosal surface of the colon than was previously possible. Among the many details visible, it is important to recognize relevant findings by their characteristic staining pattern.

In our study [1], all visible lesions were first stained and then classified according to the pit pattern classification [2]. In patients with unremarkable conventional colonoscopy findings (no lesions visible), the sigmoid colon and rectum were examined again with chromoendoscopy. With the help of vital staining, the number of diagnosed adenomas was increased.

Our colleagues Orlowska and Zych offer some substantial criticisms of the classification of adenomatous changes used in our study. One pathognomonic diagnostic criterion for adenomas is epithelial dysplasia. Adenomas are classified according to the new World Health Organization Classification (2000) into non-invasive low-grade dysplasia and high-grade neoplasia. However, the current study already started in 1999, and adenomas were therefore classified into three categories. The first group consists of adenomas without significant epithelial dysplasia. These were summarized under the term “adenomas without epithelial dysplasia”. By definition, these are low-grade intraepithelial neoplasias according to WHO 2000. Lesions with more advanced epithelial dysplasia, including those falling under the previously used terms moderate and severe dysplasia, were classified as low-grade and high-grade epithelial dysplasia, respectively.

Following the new Vienna classification, lesions formerly classed as low-grade and moderate-grade dysplasias can now be assigned to category 3, low-grade intraepithelial neoplasia. In “normal” adenomas, the term “low-grade intraepithelial neoplasia” can lead to some confusion, and we therefore used the term “without significant epithelial dysplasia”. The term “without dysplasia” is certainly misleading and not appropriate. We hope that this statement will clarify the point criticized by Orlowska and Zych.

Aberrant crypt foci are generally limited to a few crypts and are only visible after staining and magnification [3]. In the overwhelming majority of patients, we stained only the visible mucosal lesions selectively. However, with the new methods of chromoendoscopy and magnification endoscopy, it is possible to obtain a level of resolution during the examination that is in the range of tiny or just developing adenomas and aberrant crypt foci. The clinical significance of these minimal findings cannot be assessed at present. Follow-up studies on patients with discrete findings of this type will hopefully demonstrate the clinical relevance of minimal adenomatous changes of this type.

References

• 1 Kiesslich R, von Bergh M, Hahn M. et al . Chromoendoscopy with indigo carmine improves the detection of adenomatous and nonadenomatous lesions in the colon.  Endoscopy. 2001;  33 1001-1006
• 2 Kudo S, Tamura S, Nakajima T. et al . Diagnosis of colorectal tumorous lesions by magnifying endoscopy.  Gastrointest Endosc. 1996;  44 8-14
• 3 Takayama T, Katsuki S, Takahashi Y. et al . Aberrant crypt foci of the colon as precursors of adenoma and cancer.  N Engl J Med. 1998;  339 1277-1284