Identification of a mislabeled fixed specimen by DNA analysis

Formalin-fixed, paraffin embedded surgical specimens can be identified by genotypic analysis. DNA was extracted from single sections of fixed tissue and amplified by the polymerase chain reaction for the human leukocyte antigen (HLA) DQ alpha and low density lipoprotein receptor genes. These two loci are polymorphic and fixed specimens can be distinguished based on differences between these alleles. The examination can be performed in 2 days and the HLA DQ alpha test utilized a nonisotopic color detection method. In this case report, a mislabeled specimen was identified as a section from a mastectomy because they had identical genotypes. Molecular genetic analysis of the DNA present in fixed specimens can yield information not otherwise evident from the histology.