Short tandem repeat analysis: a practical tool to identify specimen mix-ups in the pathology laboratory

Despite all precautions in pathology laboratories, contaminations and specimen mix-ups still occur and can negatively impact both patients and institutions. We present two cases in which short tandem repeat (STR) analysis was used to assert the correct identity of specimens. The first patient had a biopsy diagnosis of triple negative invasive carcinoma of no special type of the breast. Sample mix-up with another biopsy was suspected, because in her post-chemotherapy mastectomy specimen, a hormone receptor-positive lobular carcinoma was diagnosed. STR analysis displayed a complete common loci profile of the patient's biopsy and mastectomy, supporting that no mix-up occurred. The second patient underwent hysterectomy due to cervix squamous cell carcinoma. A fragment of adenocarcinoma was identified and confirmed by STR profile to be a contaminant. STR analysis is a fast, easy-to-perform, and widely available technique which can clarify contaminations and specimen mix-ups in pathology laboratories.