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The range of pathologies that lymph node (LN) fine needle cytology (FNC) may encounter is extremely wide and ancillary techniques, in addition to traditional smears, are generally required to reach reliable cytologic diagnoses. Storing part of the cytologic material may be useful or necessary for molecular testing. The main difficulties concern the generally small size of the sample and the different methods of acquisition of LN-FNC. Therefore, the preanalytic phase is extremely important for LN-FNC. This article outlines the management of LN-FNC material, vials, technical devices (e.g.: additional smears, cytospin slides, LBC slides, cards, resins, etc.) and main ancillary techniques to assess their optimal application, taking into account the different diagnostic needs and cell storage.

Fine needle biopsy (FNB) with cytology has long been regarded as an excellent technique as the first choice for diagnosing adult tumours. Being an inexpensive minimally invasive technique with high accuracy and diagnostic immediacy through rapid on-site evaluation, it is also ideal for implementation in the paediatric setting, particularly in developing countries. Furthermore, it allows complementary and advanced procedures such as flow cytometry, polymerase chain reaction (PCR) or fluorescence in situ hybridization (FISH), among others, which enhances the diagnostic capacity of this technique and gives it a key role in risk stratification and therapeutic decision-making for several tumours. The advantages of FNB are optimized in the setting of a multidisciplinary team where cytologist, clinician and radiologist play leading roles. Paediatric tumours are rare and most ancillary techniques are cost-effective but complex to be implemented in small centres with limited experience in paediatric pathology. Therefore reference centres are essential, in order to establish teams with extensive experience and expertise. Hence, any child with a suspected malignancy should be directly referred to a paediatric oncology unit. Focusing on a practical approach to the assessment of paediatric lymphadenopathies and non-central nervous system solid tumours we review the effectiveness of FNB as applied concurrently with ancillary techniques in a multidisciplinary approach to the diagnosis, prognosis and therapeutic decisions of paediatric tumours and tumour-like lesions.

Wilms' Tumour (WT) is the most common kidney tumour in childhood, this fact and the embryonic complexity of WT create, whenever one of its three classical components predominates in cytologic smears, difficulties in the differential diagnoses with other less common entities. In the present study, we review the cytological and immunohistochemical characteristics of three children renal tumours, a Clear Cell Sarcoma of the Kidney (CCSK-case1), a Cellular Mesoblastic Nephroma (CMN-case2) and a Metanephric Adenoma (MA-case3) and compare them, for differential diagnostic purposes, with smears of blastematous, mesenchymal and epithelial predominant WTs, previously diagnosed in our Department. In all cases a mass was detected in the abdomen (2 and 8 year old children-cases 1 and 3, respectively), and pre-birth in case 2 (the tumour was detected during pregnancy). Fine needle biopsy was performed followed by routine cytologic examination. The presence of moderate amount of blue pale cytoplasm in neoplastic cells (case1), the presence of tightly cohesive, bland, spindle tumour cells (case2) and the identification of small, well differentiated epithelial tubules with psammoma bodies in case 3, were the main morphologic characteristics that we think represent the most important elements for distinguishing our cases from a WT. Immunoreactivity was only helpful in case 1 as we found a characteristic dot-like pattern positivity for vimentin, in the absence of immunoreactivity for the other markers that are usually positive in WT. Summing up, these three cases demonstrate that cytopathologists should be aware of the occurrence of uncommon renal neoplasms in childhood and should be acquainted with their characteristics, in order to avoid false diagnoses.