Synchronous serous peritoneal carcinoma and infiltrating mucinous appendicular adenocarcinoma. Immunohistochemical and molecular study.

Trias Isabel1,2,3, Verdú Montse1,2, Rodón Natalia2, Orellana Ruth1, Barrios Pedro3, Román Ruth2, García-Peláez Beatriz2, Díaz Olga2, Puig Xavier 1,2,3

1 Histopat Laboratoris, 2 Biopat, Biopatología molecular SL, 3 Hospital de Barcelona. Barcelona, Spain (SCIAS), Grup Assistència, Barcelona (Spain).


Objective: To demonstrate the value of molecular studies in daily diagnosis.

Methods: Case report. 67y old woman had increased CA125, CA53, normal CEA and ascites with peritoneal carcinomatosis. Laparoscopic exploration with biopsies demonstrated mucinous perforated appendicular tumor with extra-appendicular acellular mucin and serous carcinoma peritoneal implants. Ancillary studies in both components were done suggesting the presence of synchronous carcinoma. Patient received neoadjuvant chemotherapy and cytorreduction surgery.

Final histology showed infiltrating appendicular mucinous adenocarcinoma and peritoneal infiltrating serous carcinoma. Focally, both components were admixed. Immunohistochemistry and molecular studies confirmed existence of 2 carcinomas

Immunohistochemistry of mucinous adenocarcinoma was positive for CK20,CK7,CA125,CEA,CDX2,P53 and negative for ER7PR,WT1,PAX8. Serous carcinoma was positive for CK7,CA125,ER/PR,WT1,PAX8 and negative for CK20,CEA,CDX2,P53.

Molecular studies on mucine showed KRAS mutation(GD12) with WT BRAF. On mucinous adenocarcinoma we found KRAS mutation (GD12), WT BRAF, LOH 18q and 17p.

Serous carcinoma had WT KRAS and BRAF with no chromosomal alterations.

Conclusion: Different immuno and molecular profiles provided a proper diagnosis of two independent neoplasms. We emphasize the finding of mutations in the acellular mucin demonstrating the value of molecular analysis.


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