Needle rinse cell blocks as an ancillary technique: Diagnostic and clinical utility in gastrointestinal neoplasia

Abstract

Background Fine‐needle aspirate (FNA) cytology is often the first‐choice method for diagnosing gastrointestinal nodular lesions. The FNA material can be converted to histopathology specimens by a needle rinse cell block (NRCB) technique, allowing ancillary studies to refine the cytologic diagnosis. Despite use in human pathology, NRCB has never been applied to canine or feline gastrointestinal neoplasia. Objective This study described NRCB methodology and its diagnostic utility in specific cases of neoplastic gastrointestinal lesions. Methods Needle rinses with saline were performed after ultrasound‐guided FNAs of two intestinal lymphomas (canine and feline) and a canine gastrointestinal stromal tumor (GIST). The NRCB was prepared using the cell tube block technique and processed for paraffin embedding. Routine immunohistochemistry protocols (using CD3, PAX‐5, and Ki‐67 for lymphoma cases and vimentin, desmin, S‐100, and KIT markers for GIST) were applied to NRCB sections, and the results were compared with matched tissue biopsies. Results NRCBs with adequate cell numbers, preservation, and good separation of blood were obtained. The diagnosis and immunophenotyping were confirmed in both cases of lymphoma in NRCBs. In the GIST, the immunolabeling of the neoplastic cells in NRCB was completely concordant with the tissue biopsy. Conclusions The described methodology is suitable for veterinary settings, having few technical requirements and low invasiveness. The presented cases of gastrointestinal neoplasia highlight the utility of NRCBs as a platform to conduct ancillary studies and refine the cytologic diagnosis.

Osteosarcoma diagnosed in a dog using a formalin‐fixed fine‐needle aspirate biopsy

“…Other comparative techniques include gel, cell block, and needle rinse cell block. [1][2][3][4] The resultant tissue architecture and arrangement were very similar to full-thickness biopsy and with the presence of osteoid supporting the diagnosis of osteosarcoma. The interpretation of the initial routine cytology was osteosarcoma or less likely plasma cell tumor.…”

“…With direct aspiration and formalin fixation, similar architecture was maintained when compared to histopathology. Other comparative techniques include gel, cell block, and needle rinse cell block 1–4 . The resultant tissue architecture and arrangement were very similar to full‐thickness biopsy and with the presence of osteoid supporting the diagnosis of osteosarcoma.…”

“…Histopathology of fine‐needle biopsies is a minimally invasive technique that allows for a quick and adequate sample collection with no disruption of the skin or other tissues surrounding the mass. Gel, cell‐block, and needle rinse cell block preparations have been used on cytologic specimens to concentrate nucleated cells for diagnostic viewing 1–4 . To the authors' knowledge, this is the first time a FNA biopsy expelled directly in formalin has been used to confirm a cytologic suspicion of osteosarcoma or any tumor from cytology to histopathology without using cell‐block, gel, or other special substrates or techniques.…”

“…on cytologic specimens to concentrate nucleated cells for diagnostic viewing. [1][2][3][4] To the authors' knowledge, this is the first time a FNA biopsy expelled directly in formalin has been used to confirm a cytologic suspicion of osteosarcoma or any tumor from cytology to histopathology without using cell-block, gel, or other special substrates or techniques. These techniques appear to be used on fluids and bone marrow, whereas the CytoHisto technique was used on solid tissue.…”

Detection of Lymphoid Markers (CD3 and PAX5) for Immunophenotyping in Dogs and Cats: Comparison of Stained Cytology Slides and Matched Cell Blocks

“…The CB was obtained following the cell tube block technique [ 20 , 21 ]. Briefly, capillary tubes were filled with effusion and needle rinse fluids, sealed with clay, and spun in a microhematocrit centrifuge (12,700 g for 5 min).…”