[Latar belakang. Berdasarkan WHO, lesi-lesi prekursor dapat berkembangmenjadi karsinoma kolorektal melalui 2 jalur yaitu adenoma - carcinomasequence dan serrated pathways. Adenoma carcinoma sequence diawali sel atipik- adenoma displasia ringan - adenoma displasia keras -karsinoma kolorektal,sedangkan serrated pathways dimulai dari aberrant crypt foci (ACF) - poliphiperplastik - serrated adenoma (SA) - karsinoma kolorektal. Salah satukomponen penting pada lesi tersebut adalah musin yang berfungsi untukmelindungi lapisan mukosa saluran pencernaan. Musin dapat mengalamiperubahan pada tumor ganas yang berperan dalam proses diferensiasi, proliferasidan invasi sel tumor. Kepustakaan mengatakan bahwa pulasan IHK Mucin-6(MUC6) dapat digunakan sebagai penanda bagi serrated adenoma dan adenomakonvensional displasia keras.Tujuan. Untuk mengetahui ekspresi MUC6 aberrant di sitoplasma sel epitelkripta mukosa kolorektal pada serrated adenoma (SA) dan adenoma konvensionaldisplasia keras.Bahan dan cara. Penelitian ini dilakukan secara retrospektif, menggunakan studianalitik deskriptif potong lintang, dengan mengumpulkan kasus serrated adenoma(SA) dan pembanding menggunakan kasus adenoma konvensional displasia kerasmasing-masing 20 kasus. Dilakukan pulasan immunohistokimia (IHK) Mucin-6(MUC6) terhadap semua kasus.Hasil. Indeks ekspresi MUC6 aberrant kelompok serrated adenomamenunjukkan hasil sedang-kuat pada sebagian besar kasus, sedangkan kelompokadenoma konvensional displasia keras menunjukkan hasil negatif dan positiflemah pada sebagian besar kasus. Maka dapat disimpulkan terdapat hubunganbermakna antara ekspresi MUC6 aberrant pada kelompok serrated adenoma (SA)dan adenoma konvensional displasia keras, dengan nilai p=0,005.Kesimpulan. Terdapat hubungan bermakna antara ekspresi MUC6 aberrantkelompok kasus serrated adenoma (SA) dan adenoma konvensional displasiakeras., Background. Based on WHO, precursor lesions can develop into colorectalcarcinoma through two pathways, namely adenoma - carcinoma sequencepathways and serrated pathways. Adenoma carcinoma sequence begins atypicalcells - adenoma with mild dysplasia - adenoma with severe dysplasia - colorectalcarcinoma, whereas serrated pathways begins aberrant crypt foci (ACF) -hyperplastic polyps - serrated adenoma (SA) - colorectal carcinoma. One of theimportant components of the lesion is the mucin layer which serves to protect thegastrointestinal mucosa. Mucin may experience changes in malignant tumorswhich play a role in the differentiation, proliferation and invasion of tumor cells.The literature says that the outward appearance of IHC Mucin-6 (MUC6) can beused as a marker for serrated adenoma and conventional adenoma with severedysplasia.Objective: To find expression aberrant of MUC6 in the cytoplasm of epithelialcells in the colorectal mucosal crypts serrated adenoma (SA) and conventionaladenoma with severe dysplasia.Materials and method. This study was conducted retrospectively, using a crosssectionaldescriptive analytic study, by collecting case serrated adenoma (SA) anda comparison using conventional adenoma with severe dysplasia case each of the20 cases. Do outward MUC6 immunohistochemistry staining in all cases.Results. Index aberrant expression of Mucin-6 (MUC6) serrated adenoma groupshowed moderate to strong results in most cases, while the conventional adenomawith severe dysplasia was negative and weakly positive in most cases. So we canconclude there is a relationship between the aberrant expression of Mucin-6(MUC6) in the serrated adenoma (SA) group and conventional adenoma withsevere dysplasia, with p= 0.005.Conclusion. There is a relationship between the aberrant expression of Mucin-6(MUC6) serrated adenoma (SA) group and conventional adenoma with severedysplasia.]