Clear Cell Colon Adenocarcinoma with Enteroblastic Differentiation: A Rare Case Report with Literature Review

Primary clear cell adenocarcinoma of the colon is an exceptionally rare malignancy, with an incidence reported between 0.086 and 2.05%. Furthermore, enteroblastic differentiation in colorectal adenocarcinoma has been documented in approximately 4% of cases. Given the rarity of these conditions, additional data are necessary to elucidate their clinicopathological characteristics and potential interrelations. This report presents a rare case accompanied by a review of relevant literature.

A 31-year-old female patient presented with symptoms indicative of ileus. A right hemicolectomy revealed an annular colonic lesion, histologically consistent with clear cell adenocarcinoma. Immunohistochemical analysis demonstrated enteroblastic differentiation and confirmed the colonic origin of the tumor. Molecular analysis identified wild-type RAS and BRAF genes, but a p.Glu545Lys mutation in the PIK3CA gene was noted. During the treatment course, the patient developed distant metastasis.

While enteroblastic differentiation has been described in gastric clear cell adenocarcinomas, no established definition exists for its colonic counterparts. The number of case reports and studies exploring the clinical and molecular features of these tumors is limited. The available evidence suggests that these tumors may exhibit a more aggressive clinical course compared to conventional colorectal adenocarcinomas. Larger case series are required to enhance our understanding of the biological behavior and therapeutic implications of this rare tumor subtype.