Due to highly advanced veterinary care, the pets are growing older and, consequently, with the relative frequency, malignant tumors are growing too. Dominant and subordinate cues reinforce expectations of pets’ function, serving as family members and thus receiving the same quality of care as people’s disease, children included. Histopathological studies services are available based on request by Histopathological clients through the Laboratory of Averroes Laboratories (ARL).
PARR: an acceleration of a PCR for the deciphering of canine lymphoproliferative diseases
The lymphoproliferative diseases are one of the most diagnosable diseases in dogs. In other words, their task is to distinguish neoplastic lymphoid disorder – that is, lymphomas and leukaemias – from non-neoplastic proliferation of lymphoid tissue or hyperplastic reactions. However, assessment of nodal or extranodal lymphoproliferative processes often poses difficulties in the advancement of the diagnosis for a veterinary pathologist. PARR test will furnish further information whether the clonal, neoplastic nature of lymphoid cells involved or polyclonal, reactive nature of lesional lymphoid cells. Despite the fact that histological diagnosis associated with specific immunohistochemical staining is rather effective to determine neoplastic or reactive processes in a considerable number of cases of lymphoproliferative disorders, classical histopathology fails to demonstrate the clonal nature of neoplastic lymphoid cells – the conceptual identifier of lymphoid neoplasia.
Basics of PARR
The canine PARR test is based on the sequences of all loci involved in canine lymphocyte antigen receptor rearrangements. The PARR has been validated in a very large range of canine lymphoproliferative lesions, including all subtypes of canine lymphomas, according to the current WHO classification. So the test has been validated in the various types of large cell lymphomas, small cell lymphomas and indolent lymphomas. Also rare subtypes like angiocentric lymphomas were included in the test panel. Furthermore, the various intestinal and cutaneous lymphomas were included, as well as the recently characterised hepatosplenic canine lymphoma.
Additional information
Both paraffin-embedded, formalin-fixed tissue and smears are suited for analysis by PARR. In the case of smears as DNA source for the PARR, we prefer stained smears, as a visual inspection of the smear is necessary to make an assessment of the amount of DNA that can be isolated from the smears. Preferably submit several stained smears. The staining procedures used in cytology do not interfere in a negative way. For formalin-fixed tissues, please submit the wax block, which will be returned once the results of the PARR test have become available. If it is not possible to submit the wax block, please submit three 10µm paraffin sections in an Eppendorf tube and a 4µm HE-stained mounted section of the wax block for a microscopic inspection of the tissue. We report on PARR results in both the T-cell and B-cell populations. The results are reported in 5 to 10 working days (depending on the day of arrival of the tissue).