BRCA1 germline mutation presenting as an adenocarcinoma of unknown primary

The work-up of adenocarcinoma of unknown primary usually includes history, physical examination, radiographic imaging, tumor markers, and more recently molecular and genetic information. We report here on how the suggestion by family history of a BRCA1 mutation guided the diagnostic and therapeutic approach in a patient with metastatic carcinoma of unknown primary.

BRCA1 mutation was screened for by polymerase chain reaction (PCR) and single-strand conformational polymorphism analysis. Primers for PCR amplification included selected BRCA1 exons 2, 110, 11L, 13, and 20. The PCR product was cloned into a PCRII vector and sequenced with a Sequenase Version 2.0 Sequencing Kit.

Single-strand conformational polymorphism analysis suggested a mutation in the region of exon 20 and sequencing confirmed the presence of a germline mutation 5382insC.

This case illustrates an unusual presentation of adenocarcinoma of unknown primary in a patient with a germline BRCA1 mutation, the use of a suspected germline mutation to guide the work-up and treatment, and finally the value of positron emission tomography scanning in the work-up of an unknown primary.