"Fine Needle Aspiration Indications" TUMOR TIDBITS, A BIWEEKLY EMAIL NEWSLETTER FROM GULF COAST VETERINARY ONCOLOGY Number 100; June 20, 2003. ======================================================================= THIS WEEK'S TUMOR TIDBIT: FINE NEEDLE ASPIRATION INDICATIONS ======================================================================= Free Cancer Therapy for 4 months! Dogs without lymphoma having a hematocrit between 19% and 37% and a creatinine <1.8 may be eligible for this anemia study. The qualification examination is provided at no cost and eligible dogs may have all services provided at no charge (including any appropriate surgery, radiation, or chemotherapy) for 4 months. Call our offices in Houston (713.693.1166, Ms. Kelly Griffice) or San Antonio (210.822.1913, Ms. Waynette Wheeler) for additional information. Want a copy of our latest Oncology Handbook? A download is available at: http://www.gcvs.com/oncology/download.htm We support research! Visit our Foundation web site at: http://www.gcvs.com/gcvef/index.htm ======================================================================= FINE NEEDLE ASPIRATION INDICATIONS With proper technique and slide preparation, the accuracy of fine needle aspiration (FNA) and cytology may exceed 90%, and can provide a diagnosis at 10-30% of the cost of the surgical biopsy. The simplicity of sampling methods and the characteristic appearance of some neoplasms has encouraged many veterinarians to gain skills in cytopathologic interpretation. This Tumor Tidbit (our 100th by the way) describes the indications for FNA in the veterinary clinic. The indication for FNA is a nodule or mass lesion, either palpable or visible by some imaging method, that strongly suggests cancer and for which the relative number of diagnostic possibilities is limited. FNA is frequently done for cutaneous masses, representing primary tumors of skin or its supporting structures, or metastases to skin. Tumors reach the skin from invasion of an underlying tumor, through the lymphatics or bloodstream, or by extranodal extension of tumor into skin. Fear of seeding the needle biopsy tract was once a major concern in performance of the FNA. Examination of the published data indicates that this concern is not justified. Cases of documented needle tract seeding with the use of fine needles are exceedingly rare especially when 22 ga. or smaller needles are used. New and improved imaging techniques have made FNA of internal organs accurate and cost-effective. Ultrasound guidance can be used for the sampling of the liver, pancreas, spleen, kidney and retroperitoneal structures. The spleen is frequently aspirated as part of the staging process for dogs and cats with lymphoma and mast cell tumors. The liver is often aspirated to diagnose metastases. The pancreas is aspirated less frequently, but FNA may allow a diagnosis of pancreatic carcinoma or lymphoma to be established. Aspiration of the kidney is done for evaluation of solid renal masses. Aspirates of the adrenal glands might be accomplished. Sarcomas, lymphomas and metastatic tumors might also be aspirated under ultrasound guidance. Puncture of a major abdominal blood vessel is usually not a complication using small gauge needles as the vessels are apparently rapidly sealed, and peritonitis is uncommon. The passage of the biopsy needle through viscera during transabdominal aspiration does not appear to be a serious problem as the size of the needle is typically smaller than surgical sutures used in these organs. Improvements in imaging techniques, including fluoroscopy, computed tomography and ultrasonography have also made transthoracic needle aspirations accurate. FNA is a preferred diagnostic method if clinical and radiographic findings are suggestive of malignancy. It is particularly useful for the diagnosis of small tumors located peripherally in lungs and not associated with major airways. FNA is also helpful for the evaluation of mediastinal lesions like lymphoma or thymoma. Although complications include pneumothorax or hemothorax, these are uncommon with small-bore needles. FNA is also useful for bone lesions bone lesions. The cortical surface is examined by ultrasonography, and the needle is introduced under ultrasound guidance through breaks in the cortical bone surface. There are some inherent limitations to cytology. For example, for surface-oriented lesions, FNA does not allow determination of the thickness or depth of invasion. Cytologic preparations are generally not satisfactory for determination of tumor grade, or degree of malignancy. There may also be difficulties in distinguishing benign from malignant lesions; this is especially true in veterinary medicine when interpretations are made of aspirates derived from tumors localized in mammary glands, thyroid glands and structures in the circumanal region. FNA and cytologic interpretation is easy, quick, and allows the veterinarian to prepare the pet owner for the process of proper diagnosis and staging of the disease condition, allowing improved care and quality of life for the pet. ======================================================================= As always, we hope this info helps and don't hesitate to call or email us Gulf Coast Veterinary Oncology! Kevin A. Hahn, DVM, PhD, Diplomate ACVIM (Oncology), drhahn@gcvs.com Janet K. Carreras, VMD, Diplomate ACVIM (Oncology), drcarreras@gcvs.com Glen K. King, DVM, MS, Diplomate ACVR (Radiology & Radiation Therapy), drking@gcvs.com Gulf Coast Veterinary Diagnostic Imaging & Oncology 1111 West Loop South, Suite 150, Houston, TX 77027 P: 713.693.1166 F: 713.693.1167 W: www.gcvs.com ======================================================================= Copyright © 2003, Gulf Coast Veterinary Oncology