Identification of a novel PRR15L-RSPO2 fusion transcript in a sigmoid colon cancer derived from superficially serrated adenoma

• DOI: 10.1007/s00428-019-02604-x
• Publication Date: 2019-06-17T07:02:42Z
• Authors: Yasuhiko Mizuguchi; Taku Sakamoto; Taiki Hashimoto; Shunsuke Tsukamoto; Satoru Iwasa; Yutaka Saito; Shigeki Sekine
• Keywords: Adenoma; 0303 health sciences; Carcinogenesis; Colonic Polyps; Proteins; Adenocarcinoma; Middle Aged; 3. Good health; Proto-Oncogene Proteins p21(ras); Sigmoid Neoplasms; 03 medical and health sciences; Fatal Outcome; Mutation; Humans; Intercellular Signaling Peptides and Proteins; Female; Lymph Nodes; Gene Fusion; Neoplasm Metastasis

Superficially serrated adenoma (SuSA) is a recently proposed subtype of colorectal serrated lesion. We here report a sigmoid colon cancer derived from SuSA, which exhibited aggressive clinical behavior. Endoscopically, the tumor appeared as a superficial elevated lesion with a large nodule. Histological examination of the surgically resected material showed tubular adenocarcinoma associated with SuSA. Although tumor invasion was limited to the submucosal layer, lymph node and extranodal metastases were detected. The patient subsequently developed peritoneal metastases and died 15 months after surgery. Molecular analyses identified a KRAS mutation and a novel PRR15L-RSPO2 fusion, which retains the entire coding region of RSPO2, in both SuSA and adenocarcinoma components. The present study demonstrates the malignant potential of SuSA and expands the spectrum of RSPO fusions in colorectal neoplasms.