췌장낭성종양의 병리진단에서 분자병리 검사의 활용은 통상적인 세포 또는 조직 진단이 어려운 경우 점진적으로 확대될 것으로 예상된다. 세포 또는 낭액에서 검사 결과에 필요한 충분한 디오시리보핵산(DNA)이 확보된다면 특정 유전자 변이를 확인해서 췌장낭성종양의 감별 진단이 가능하며 대표적인 유전자 변이에는 KRAS, GNAS, CTNNB1, VHL 변이 등이 있다. 하지만 분자병리 검사를 활용하는 경우에도 임상-영상의학적 소견을 참고하여 기본적인 병리진단을 한 후에, 이를 뒷받침하는 자료로 활용되는 것이 바람직하다. 차세대염기순서분석 검사는 소량의 세포 또는 조직으로 다수의 유전자 변이를 동시에 확인할 수 있는 장점이 있어 사용되는 범위가 확대될 것으로 기대되지만 적절한 정도 관리를 거치지 않으면 위음성의 결과로 보고될 위험성이 있으며 병리의사의 정도 관리를 거친다고 하더라도 30% 내외의 실패율을 보일 수 있다고 보고되어 있다.

Ampulla of Vater (AoV) is a small dilated duct less than 1.5 cm long, formed by the union of pancreatic duct and common bile duct. AoV has also anatomic layer of mucosa, sphincter of Oddi, perisphincteric or duodenal submucosa, and duodenal proper muscle, which corresponds to mucosa, muscularis mucosa, submucosa, and proper muscle layer of other gastrointestinal tract organs, respectively. Because of its small compact size and variation of anatomic structure, it is sometimes difficult to identify layering architecture of AoV. This anatomic difficulty may cause some problem in T classification of ampullary carcinoma (AC). The most confusing point in T classification is the vague definition of T2, “Tumor invades duodenal wall”. It seems that duodenal wall includes duodenal mucosa, submucosa, and proper muscle layer. However there is no precise description or definition about duodenal wall that might lead personal variation in T classification of AC staging. We found that clinical course of AC with perisphincteric and/or duodenal submucosal invasion is more close to AC with T2 than T1. Although it is described as T1b according to T classification scheme of ordinary gastrointestinal tract cancer, we thought AC with T1b may have more high-grade malignant potential than those of other gastrointestinal (GI) tract malignancy. AC showed various clinicopatholgic findings that represent heterogeneous tumor groups within category of AC. Recently site-specific classification of AC was introduced, and it showed relatively well-categorized clinical prognosis. It may be reasonable to understand site-specific tumorigenesis in AC. The standard gross protocol is needed to evaluate pathologic T classification of AC. In conclusion, ampullary neoplasm is composed of various subtypes, which require a separate approach according to anatomic epicenter of ampullary neoplasm. Although submucosal invasion in AC was classified into pT1b, its’ biologic behavior is more close to pT2.