Identification of tumor specimens by DNA analysis in a case of histocytological paraffin tissue block swapping

Abstract

We report on a patient who was diagnosed with high-grade breast carcinoma by all the pre-surgery clinical evidence of malignancy, but histopathological reports did not reveal any such tumor residue in the post-surgical tissue block. This raised a suspicion that either exchange of block, labeling error, or a technical error took place during gross examination of the tissue. The mastectomy residue was unprocurable to sort out the problem. So, two doubtful paraffin blocks were sent for DNA fingerprinting analysis. The partial DNA profiles (8-9/15 loci) were obtained from histocytological blocks. The random matching probability for both the paraffin blocks and the patient’s blood were found to be 1 in 4.43E4, 1.89E6, and 8.83E13, respectively for Asian population. Multiplex short tandem repeat analysis applied in this case determined that the cause of tumor absence was an error in gross examination of the post-surgical tissue. Moreover, the analysis helped in justifying the therapy given to the patient. Thus, with DNA fingerprinting technique, it was concluded that there was no exchange of the blocks between the two patients operated on the same day and the treatment given to the concerned patient was in the right direction.

DNA perspectives of fixed and paraffin embedded human tissues as resource materials for the identification

“…Due to remarkable DNA damage in both the paraffin blocks partial DNA profiles were obtained. However a critical evaluation of 8-9 loci was sufficient for the conformational results (Raina et al 2011). 2.…”

“…The reason being DNA extracted from these fixed tissues finds its greatest applications in retrospective studies notably in sudden unexplained death where FF and FFPET is a unique source of genetic material and therefore represents an invaluable resource for genetic studies in situations where subjects are no longer alive as reported in the literature (Chugh et al 2004;Doolan et al 2008). DNA extracted from these tissues finds great applications in the identification of a person such as in paternity testing, abduction or soldier missing in action, in crime cases where biological evidence is available for comparison, identifying mismatched specimens for reevaluation Raina et al 2011) or to clear doubtful approaches regarding contamination issues (Popiolek et al 2003) and in insurance cases (Liu et al 2009). However because of the declining state of these samples and a lack of standardized preservation method, DNA recovery from these samples along with its amplification, is a challenging task due to the apparent nucleic acid degradation by way of aging of the specimen in the fixative or the pH of the fixative by gradual changes of formaldehyde to formic acid thereby hydrolyzing the DNA and extensive modification that affects both the quality and quantity of DNA (Gilbert et al 2007;Gillio-Tos et al 2007;Huijsmans et al 2010).…”