원발성 위 림프종은 비교적 드문 질환으로서 위에서 발생하는 악성종양의 1-7%를 차지한다. 위 림프종은 전체 위장관 림프종의 60-65%로 가장 흔하며 최근 수십년간 그 빈도가 증가하고 있다. 위 점막연관성 림프종(mucosa-associated lymphoid tissue lymphoma)은 전체 위 림프종의 40% 정도로 보고되고 있고 나머지는 대부분 미만성 거대 B세포 림프종(diffuse large B cell lymphoma)이 차지하고 있다.
헬리코박터 파일로리(Helicobacter pylori)는 4-6개의 편모를 가진 그람 음성의 나선형 세균으로 주로 위점막에서 발견된다. 이는 인간에게 감염을 일으키는 가장 흔한 균 중 하나로 전세계 인류의 절반 정도에서 감염을 일으키며 한국에서의
유병률은 54%로 보고된 바 있다. 헬리코박터 파일로리 감염은 저등급 위 점막연관성 림프종의 발병에 있어서 가장 중요한 원인으로서 약 90%에서 헬리코박터 감염이 동반되어 있으며 제균 치료만으로도 질환의 완전 관해에 도달할 수 있다. 따라서 위 점막 연관성 림프종 환자에서 헬리코박터 감염의 진단은 환자의 치료 방침을 정하는데 있어서 가장 핵심적인 역할을 하게 된다.
위내 헬리코박터 감염을 진단하는 방법은 여러 가지가 있으며 크게 침습적인 방법과 비침습적인 방법으로 나눌 수 있다. 침습적 방법에는 급속요소분해검사(rapid urease test, CLO test)와 조직검사가 있으며 내시경을 이용하여 위점막 조직을 일부 채취하여 검사를 하게 된다. 비침습적 검사에는 요소호기검사(urea breath test, UBT), 대변 항원 검사(stool antigen test), 혈청 검사가 있다.
우리나라는 외국에 비하여 내시경 검사의 비용이 비교적
저렴하며 헬리코박터 파일로리의 유병률이 높으므로 급속요소분해검사가 헬리코박터 감염의 일차 진단 도구로써 유용하다고 할 수 있다. 급속요소 분해검사에서 음성이 나올 경우 항상 위음성의 가능성을 고려해야 하며 요소호기검사, 혈청학적 검사 등의 추가 검사를 시행하여 헬리코박터 감염의 유무를 반드시 확인해야 한다. 또한 국내의 높은 항생제 및 양성자 펌프 억제제 처방률을 고려하였을 때 환자의 최근 약물 복용력 및 이전 제균 치료에 대한 확인이 매우 중요하다.
헬리코박터 파일로리는 위 내의 점막에 고르게 분포하지 않기 때문에 내시경을 통하여 급속요소분해검사를 위한 위 점막 조직을 얻을 경우 조직채취의 위치가 검사의 정확도에 큰 영향을 주게 된다. 국내 가이드라인을 포함한 대부분의 가이드라인에서는 전정부와 체부의 위치에서 적어도 2개 이상의 조직을 얻어 검사를 시행할 것을 권고하고 있다.
헬리코박터 파일로리는 정상 위점막에 표면에서 만성적인 염증 반응을
일으키게 되며 이로 인한 위축성 변화, 장상피화생을 일으키게 되며 이 중 일부에서는 림프종, 선암 등이 발병하게 된다. 이러한 비정상적인 점막은 헬리코박터의 생존에 호의적인 환경이 아니기 때문에 감염 여부의 확인을 위하여 조직을 얻을 경우 위축성 변화나 장상피화생 등의 소견을 보이는 점막을 피하여 채취하는 것이 권고되고 있다.
위 점막연관성 림프종에서 급속요소분해검사를 위한 조직을 채취할 때 가장 검출률이 높은 위치에 대해서는 현재까지 특별한 연구가 없는 실정이다. 그러나 일반적으로 정상 점막에서 헬리코박터의 검출률이 높음을 고려할 때 위 점막연관성 림프종에서도 병변으로 보이는 위치는 피하여, 가능한 정상소견을 보이는 점막에서 조직을 얻는 것이 검출률을 높일 수 있을 것으로 기대된다.
그 외 비침습적인 검사에는 요소호기검사, 대변항원검사, 혈청검사 등이 있다. 요소호기검사는 95% 정도의 민감도와 특이도를 보이고 잇으며 환자가 좀 더 편하게
검사를 받을 수 있다는 장점이 있다. 그러나 환자가 항생제나 양성자 펌프 억제제를 복용할 경우 위음성의 가능성이 높아진다. 대변항원검사는 다클론 항체 또는 단클론 항체를 이용하여 대변 내 헬리코박터 파일로리의 항원을 검출하게 되며 다클론 항체법의 경우 87.1-93.1%의 민감도와 94.6-100%의 특이도를 보이며 단클론 항체법의 94%의 민감도와 97%의 특이도를 보이는 것으로 보고된 바 있다.
혈청검사는 비교적 저렴하고 비침습적이며 주로 ELISA를 이용한 검사법이 사용된다. 이는 헬리코박터 파일로리의 균일하지 않은 위 내 분포롤 인한 위음성의 가능성을 줄일 수 있지만 제균 치료 후에 항체가 사라지거나 역가가 의미있게 감소하기 위해서는 1년 이사의 기간이 소요되기 때문에 제균 치료의 성공 여부를 바로 판정하기에는 부적당하여 제균 치료의 추적 관찰방법보다는 감염의 선별 검사로 이용되고 있다.
결론적으로 헬리코박터 파일로리의 감염은 위
점막연관성 림프종의 발병, 치료 및 예후에 있어서 가장 중요한 인자이며 위 점막연관성 림프종이 진단되었을 경우 가능한 모든 방법을 이용하여 헬리코박터 감염의 유무를 확인하는 것이 매우 중요하다.
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