LAUSR

Fine needle aspiration (FNA) is a marginally invasive, fast and cost-effective technique to diagnose malignancy as well as other pathologies in different anatomical sites. In the last few years, there has been a significant increase in the demands on sensitivity and specificity of cytodiagnosis as well as in the requirement to produce further biological data to better determine treatment and prognosis.1 Unfortunately, cytology specimens often are not suitable for ancillary studies both for the quality and the amount of the material. Furthermore, carrying out more aspirations may not be doable. Another point to be underlined is the fact that many times pathologists adapt ancillary techniques learnt in histology to cytology specimens without bearing in mind main differences in the specimen preparation that could alter the final interpretation of the data and ultimately the diagnosis for patient care.2 This is particularly true in the case of immunohistochemistry, where the great majority of the commercially available antibodies have been selected for their reliability when used in tissues fixed in formalin and paraffin-embedded.3 4 In this article, we propose a novel approach for the immunohistochemical characterisation of tumour fine needle aspirates by taking advantage of Cytomatrix, a recently defined synthetic matrix that counts among its various characteristics the property to capture and store inside its three-dimensional structure, the biological material (micro-macro cells and cell aggregates) from needle withdrawal samples. The cytological material collected in this way can be processed as a histology specimen, allowing to perform immunohistochemical analysis with routine protocols.5 As experimental in vivo model, we chose two different spontaneous malignancy in pets, where the possibility to carry on specific diagnostic tests from fine needle aspirates would be of great support to clinicians: visceral lymphoma in dogs and cats and widespread mast cell tumour in dogs. For both tumours, immunohistochemical characterisation carries a prognostic and therapeutic value: in the case of lymphoma the B cell and T cell types carry a different prognostic value and also a potentially different therapeutic approach, for mast cell tumours, CD117 expression is predictive of response to CD117 inhibitor drugs.6 7