Primary Fallopian Tube Carcinomas In Patients With Multiple Malignancies: Utility Of Tissue Of Origin Testing

Context: The diagnosis of primary fallopian tube carcinoma (PFTC) may be difficult and require ancillary tests in patients who are genetically susceptible to cancer or have more than one malignant tumor. Objective: Usage of ancillary tests for definite diagnosis of PFTC. Design: Two occult PFTC with unusual morphology and a third case with morphologic features of serous carcinoma with clear cell changes were studied by immunohistochemistry and the molecular tissue-of-origin test (TOO).Results: The first two patients had histories of breast carcinoma; the latter was also a carrier of a BRCA1 mutation. ER immunostain was positive in both cases with WT-1 co-expressed in the latter. A third patient with metastatic papillary serous carcinoma received neoadjuvant chemotherapy prior to surgical treatment. TOO identified the malignancies as ovarian carcinomas with similarity scores of 89.5, 95.7, and 96.6. Conclusion: While TOO cannot distinguish PFTC from ovarian carcinoma, it can be useful in cases where the morphology, immunohistochemistry and comparison with previous tumors from the other sites are equivocal.