Within the USA and other resource-rich countries, the volume of pediatric FNAs can also vary greatly in different practice settings. Clinicians who have had positive experiences with FNA as a diagnostic modality are more likely to consider referring patients for FNA or to recommend the use of FNA to their colleagues, than those who have had negative experiences. Acquisition of an adequate specimen, appropriate triage, and diagnostic expertise are all required for providing a high quality FNA service. Adequate samples can be obtained by pathologists, interventional radiologists, and/or clinicians with appropriate training and expertise in performing FNAs. However, within a given institution, the type(s) and availability of qualified physicians impacts whether FNAs are performed in inpatient and/or outpatient settings, or not at all, and whether the lesions sampled are superficial and/or deep. Appropriate triage of the specimen is essential when ancillary studies are needed for a definitive or narrowed differential diagnosis. Rapid on site evaluation (ROSE) not only allows assessment of adequacy, but also guides appropriate triage of the specimen. However, ROSE can be time consuming and is deemed economically impractical in some practice settings. The availability of pathologists and/or cytotechnologists to perform ROSE can have a significant impact on whether the procedure results in a definitive or narrowed differential diagnosis and thus, on the use of FNA rather than a more invasive core or open biopsy for the primary evaluation of a mass lesion in a child or adolescent. Finally, the expertise required for accurate cytologic diagnosis of pediatric lesions is more likely to be found in settings with subspecialty-trained cytopathologists and pediatric pathologists, and can have a positive impact on the use of FNA. In general, the key elements for the acceptance and successful use of FNA as a diagnostic modality in the pediatric population are more likely to be found in an academic institution than in a community hospital.

Geographic location and practice setting also influence the type and pathologic spectrum of pediatric lesions evaluated by FNA. In resource-limited countries, malignancies comprise the majority of lesions diagnosed by FNA [4], while in resource-rich countries benign processes predominate [1]. Moreover, in resource-limited countries, a greater proportion of malignancies diagnosed by FNA are primary and/or deep-seated tumors than in resource-rich countries. In the USA, primary cytologic diagnosis of malignancies is rare; rather, FNA is primarily used for the evaluation of superficial masses, the majority of which are benign and located in the head and neck [1]. It is important to note that this pattern is observed even in institutions with robust pediatric FNA services and, in part, reflects the fact that Children’s Oncology Group therapeutic protocols are based on histologic diagnosis and associated biologic studies require frozen or formalin-fixed tissue.