The authors report three cases of parathyroid cysts examined by the fine-needle aspiration biopsy technic. A presumptive diagnosis of parathyroid cyst was made when characteristic water-clear fluid was aspirated. The diagnosis was then confirmed by parathyroid hormone (PTH) assay. The authors believe that the C-terminal/midmolecule determination should be the assay of choice, because the N-terminal-specific assay gave normal or slightly elevated results in all the cases studied. If only an N-terminal-specific PTH assay is obtained, potential for a false negative diagnosis exists. With a correct PTH assay, a specific diagnosis of parathyroid cyst can be rendered, which enables appropriate treatment of total fluid aspiration, which thereby eliminates the need for thyroid hormone treatment or surgery in most cases. A discussion of PTH assays is presented along with speculations concerning the secretion of PTH by the parathyroid gland. The previous literature detailing cytologic findings and the PTH assays of parathyroid cysts diagnosed by the fine-needle aspiration biopsy are reviewed.

A total of 135 fine-needle aspiration (FNA) biopsies from varying sites were performed in 123 children (mean, 10.5 years; range, one day to 18 years) over a five-year period. One hundred thirty (96.3%) biopsy specimens were satisfactory for evaluation. Seventy-nine cases were nonneoplastic (60.8%); among these cases, a specific diagnosis of infectious disease was made in 17 (13.1%). A diagnosis of neoplastic disease was made in 50 (38.5%) cases, of which 14 (10.8%) were benign, 28 (21.5%) were malignant, and 8 (6.2%) were neoplasms of uncertain biologic potential. The sensitivity of pediatric FNA biopsies was 90.6%, specificity 100%, positive predictive value 100%, negative predictive value 94.7%, and efficiency of the test 96.5%. There were no false-positive diagnoses and there were four false-negative diagnoses, three of which involved aspirates of the central nervous system (CNS). Ancillary studies, including immunocytochemistry (20 cases), electron microscopic examination (18 cases), microbiologic culture (8 cases), cytogenetic studies (7 cases), and flow cytometry (3 cases), were performed on the aspirated material, enabling a more specific diagnosis or supplying additional information in many cases. Definitive diagnosis by FNA biopsy enabled radiation therapy and/or chemotherapy to be administered for unresectable malignant neoplasms, provided material for culture of infectious lesions, identified benign lesions not needing surgery, and aided the surgeon in planning the extent of surgery in resectable malignant neoplasms. These results support the greater use of FNA biopsy in the pediatric population.

We reviewed the cytologic features and results of ancillary studies in eight fine‐needle aspiration biopsies (FNAB) performed by posterior approach in 8 patients with unresectable Wilms' tumor (WT). Chemotherapy was given following the FNAB diagnosis of WT, which was confirmed subsequently by histologic examination of surgically resected specimens. Indications for FNAB included: unresectable tumor, bilateral disease, initial presentation with metastatic disease, uncertainty regarding tumor site, and documentation of recurrence. Cytologic examination revealed blastemal cells (8/8 aspirates), spindle cells (3/8 aspirates), and epithelial differentiation or tubules (3/8 aspirates). There was no cytologic evidence of anaplasia in any of the cases. Immunocytochemical studies on cell blocks and/or smears showed cytokeratin positivity in 5/8 and vimentin positivity in 5/5 of the aspirates in which these studies were performed. Focal positivity for neuron‐specific enolase (NSE) was seen in 3/3 aspirates. Stains for actin and leukocyte‐common antigen were negative (0/3 and 0/2 aspirates, respectively). DNA ploidy analysis of the aspiration material by flow cytometry revealed near‐diploid populations in three aspirates. Electron microscopic findings helpful for diagnosis included: cell junctions, microvilli, flocculent basement membrane‐like material, cilia, autophagolysosomes, and lack of neuroectodermal differentiation. Diagnostic morphologic pitfalls for an incorrect diagnosis of neuroblastoma included nuclear molding (all aspirates), pseudorosette formation (one aspirate), and focal NSE positivity (3/3 aspirates). None of the tumors showed anaplasia on histologic examination. Cytologic recognition of the triphasic cellular components of WT (blastemal cells, spindle cells, and epithelial cells) can be helpful for a correct diagnosis; however, in 5/8 aspirates in this study, only the blastemal component was present. In these cases, immunocytochemical stains and electron microscopy proved useful in arriving at a correct FNAB diagnosis of WT. However, NSE positivity can be a pitfall for a diagnosis of neuroblastoma if the radiologic, clinical, and other cytologic features are not clearly delineated. Presence of cytokeratin and vimentin positivity would be helpful in the diagnosis of WT in such instances. Diagn Cytopathol 1996; 14:101–107. © 1996 Wiley‐Liss, Inc.

Eleven fine needle aspiration (FNA) biopsies were performed in five children with neuroblastoma, including one patient with peripheral neuroectodermal tumor of the thoracopulmonary region (Askin tumor). Cytologic features in conjunction with immunocytochemistry and electron microscopy on the aspirated material enabled us to make a primary diagnosis in four of the five patients and diagnose local recurrence and metastatic disease in three patients. There were no false-positive or false-negative cytologic diagnoses; therefore, diagnostic accuracy was 100%. FNA is an extremely useful technique for the primary diagnosis and management of neuroblastoma and excludes other small cell malignancies of children. The results of this study and literature review demonstrate that FNA cytology coupled with ancillary techniques of immunocytochemistry and electron microscopy is a rapid, safe, minimally invasive procedure which can aid in the diagnosis and management of patients with neuroblastoma without resorting to more aggressive diagnostic procedures in selective cases.