Coexisting tubular adenoma with a neuroendocrine carcinoma of colon allowing early surgical intervention and implicating a shared stem cell origin

• Published in: World journal of gastroenterology : WJG Vol. 23; no. 6; pp. 1106 - 1112
• Main Authors: Soliman, Mahmoud L, Tiwari, Ashish, Zhao, Qing
• Format: Journal Article
• Language: English
• Published: United States Baishideng Publishing Group Inc 14.02.2017
• Subjects: Adenocarcinoma - diagnosis; Adenocarcinoma - pathology; Adenoma - diagnosis; Adenoma - genetics; Adenoma - pathology; Adenoma - therapy; Aged; Biomarkers, Tumor - analysis; Carcinoma, Medullary - diagnosis; Carcinoma, Medullary - pathology; Carcinoma, Neuroendocrine - diagnosis; Carcinoma, Neuroendocrine - genetics; Carcinoma, Neuroendocrine - pathology; Carcinoma, Neuroendocrine - therapy; Case Report; Chemotherapy, Adjuvant; Colectomy - methods; Colon - pathology; Colonic Neoplasms - diagnosis; Colonic Neoplasms - genetics; Colonic Neoplasms - pathology; Colonic Neoplasms - surgery; Colonoscopy; Diagnosis, Differential; DNA Mutational Analysis; Humans; Immunohistochemistry; Lymphoma - diagnosis; Lymphoma - pathology; Male; Neoplasm Grading; Neoplasm Recurrence, Local; Neoplastic Stem Cells - metabolism; Proto-Oncogene Proteins B-raf - genetics; Proto-Oncogene Proteins p21(ras) - genetics; Thyroid Neoplasms; Colocalization; Colorectal; Neuroendocrine carcinoma; Tubular adenoma
• DOI: 10.3748/wjg.v23.i6.1106
• ISSN: 1007-9327

High-grade colonic neuroendocrine carcinomas (NECs) are uncommon but extremely aggressive. Their co-existence with tubular adenoma (TA) has rarely been reported. We present a 68-year-old man who was found on routine colonoscopy to have multiple colorectal TAs and an ulcerated lesion in the ascending colon. Microscopically, a poorly-differentiated invasive carcinoma juxtaposed with a TA was identified. Differential diagnosis included a poorly-differentiated adenocarcinoma, medullary carcinoma, high-grade NEC and lymphoma. The immunohistochemical profile showed positive staining for keratins, synaptophysin and chromogranin but negative for LCA, CDX2, CK7, CK20, TTF-1 and PSA, supporting the NEC diagnosis. Upon subsequent laparoscopic right hemicolectomy, the tumor was identified as a 3.0 cm umbilicated and ulcerated mass with an adjacent TA. Both TA and NEC showed positive staining for β-catenin indicating a shared colonic origin. The mitotic counts (77/10 high power fields) and a high proliferation rate (75% by Ki-67) corroborated a high-grade stratification. Mutational analysis indicated a wild-type BRAF and KRAS with mismatch repair proficiency. The AJCC(7th edition) pathologic stage is p T3, p N0, p Mx. The patient received adjuvant chemotherapy with cisplatin/etoposides for three cycles and will be followed up for a year to detect recurrence. In conclusion, the co-existence of TA with high grade-NEC in our case allowed early identificationand intervention of the otherwise asymptomatic but aggressive tumor. In addition, the finding of a highgrade NEC within a large TA in this case suggests a link between the two lesions and could represent a shared stem cell origin.