Getting to the point: indications for fine-needle aspiration of internal organs and bone

The technique of fine-needle biopsy (fine-needle aspiration or fine-needle fenestration) for cytologic evaluation can be extended to many sites beyond the traditional lymph node and skin. Intra-abdominal, intrathoracic, and bone lesions can be easily and rapidly evaluated cytologically. Percutaneous fine-needle aspiration and fine-needle fenestration are useful, accurate, and inexpensive techniques with a rapid turnaround time, and outpatient applicability. For most pets, these minimally invasive techniques do not require anesthesia or analgesia. Although risks are inherent with any invasive procedure, complications are uncommon even with visceral and intrathoracic fine-needle biopsy. Attention to appropriate technique and close patient monitoring minimize the morbidity and improve the diagnostic utility. The low cost, low risk, minimal invasiveness, and high diagnostic yield make fine-needle biopsy particularly attractive to clients. In combination with ultrasound guidance and newer staining techniques, these diagnostic procedures are invaluable to the veterinary clinician.     

ULTRASOUND-GUIDED FINE-NEEDLE ASPIRATION BIOPSY OF BONE LESIONS: A PRELIMINARY REPORT

The purpose of this preliminary study was to determine the feasibility of ultrasound-guided fine-needle aspiration biopsy of suspected neoplastic lesions of bone. Ultrasound-guided fine-needle aspiration biopsy samples were obtained in 23 patients (22 dogs and one cat) with radiographic evidence of a destructive or destructive/productive bone lesion. The lesions were located in the appendicular skeleton in 20 patients and in the axial skeleton in three. Histopathology from tissue core biopsies and/or necropsy was not deemed necessary in 11 patients where ultrasound-guided fine-needle aspiration biopsy results were conclusive for neoplasia. A cytologic diagnosis from ultrasound-guided fine-needle aspiration biopsy was confirmed by histologic samples obtained at surgery or necropsy in five patients. In one of these five, ultrasound-guided fine-needle aspiration biopsy samples were diagnostic for sarcoma when tissue-core biopsy was inconclusive. Both ultrasound-guided fine-needle aspiration biopsy and tissue core biopsy techniques were inconclusive in one patient. Ultrasound-guided fine-needle aspiration biopsy samples were nondiagnostic in five patients where a follow-up histopathologic diagnosis of neoplasia was made. It was concluded that ultrasound-guided fine-needle aspiration biopsy of bone, if diagnostic, may help avoid the need for a tissue-core biopsy in some instances. However, a negative ultrasound-guided fine-needle aspiration biopsy sample does not rule out neoplasia. A negative ultrasound-guided fine-needle aspiration biopsy should be followed by a tissue-core biopsy and histologic analysis in all patients. Ultrasound-guided fine-needle aspiration biopsy seems to be a promising technique for the diagnosis of bone lesions.     

Diagnostic value of cytologic examination of gastrointestinal tract tumors in dogs and cats: 83 cases (2001-2004)

OBJECTIVE: To determine results of cytologic examination of fine-needle aspirates and impression smears of gastrointestinal tract tumors in dogs and cats. DESIGN: Retrospective case series. ANIMALS: 38 dogs and 44 cats with histologically confirmed gastrointestinal tract tumors. PROCEDURES: Results of cytologic examination of fine-needle aspirates (n = 67) or impression smears (31) were compared with the histologic diagnosis, and extent of agreement was classified as complete, partial, none, or undetermined. RESULTS: For 48 of the 67 (72%) fine-needle aspirates, there was complete or partial agreement between the cytologic and histologic diagnoses. For 12 (18%) aspirates, the extent of agreement could not be determined because the cytologic specimen was considered unsatisfactory. For 29 of the 31 (94%) impression smears, there was complete agreement between the cytologic and histologic diagnoses, and for 2 (6%), there was partial agreement. None of the impression smears were considered unsatisfactory. Proportion of samples with complete agreement and proportion of samples with complete or partial agreement were significantly higher for impression smears than for fine-needle aspirates. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that there was moderate agreement between results of cytologic examination of fine-needle aspirates from dogs and cats with gastrointestinal tract neoplasia and the definitive histologic diagnosis. The agreement between results of cytologic examination of impression smears and the histologic diagnosis appeared to be higher.     

Comparison of results of clinicians' assessments, cytologic examination of fine-needle lymph node aspirates, and flow cytometry for determination of remission status of lymphoma in dogs

OBJECTIVE: To determine interclinician agreement when assessing remission of lymphoma in dogs and the association among results of clinicians' assessments via lymph node palpation, cytologic examination of fine-needle lymph node aspirates, and flow cytometry as determinants of remission. DESIGN: Prospective study. ANIMALS: 23 dogs with untreated lymphoma. PROCEDURE; Two clinicians independently measured large lymph nodes and cytologic examination and flow cytometry of cells from a mandibular or popliteal lymph node were performed 1 week prior to initiating treatment. Lymph node measurements with clinicians' remission assessments and cytologic examination were repeated at weeks 2, 3, and 5; flow cytometry was repeated at week 5. RESULTS: Significant correlation was identified between clinicians' remission assessments. Significant correlation between lymph node palpation and cytologic examination was identified at week 5, but not at weeks 2 and 3. Lymphoma was diagnosed in 16 of 23 (70%) dogs at initial evaluation by use of flow cytometry, although it was of limited use at subsequent evaluations and results were not diagnostic of lymphoma in any dog at week 5, including 1 dog in which lymphoma was diagnosed cytologically. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that physical examination and measurement of lymph node volume may not be sufficient for accurately determining remission, that flow cytometry alone should not be relied on as a means for diagnosis, and that cytologic examination of fine-needle lymph node aspirates should be considered as the most accurate means of determining remission status at times in which treatment modifications are considered.     

Correlation of ultrasonographic appearance of lesions and cytologic and histologic diagnoses in splenic aspirates from dogs and cats: 32 cases (2002-2005)

OBJECTIVE: To determine the accuracy of cytologic diagnosis, compared with histologic diagnosis, in determination of disease in ultrasound-guided fine-needle aspirates of splenic lesions. DESIGN: Retrospective study. SAMPLE POPULATION: Splenic specimens from 29 dogs and 3 cats. PROCEDURES: Records were searched for dogs and cats that had undergone ultrasound-guided splenic aspiration. Criteria for inclusion were ultrasonographic identification of splenic lesions and cytologic and histologic evaluation of tissue from the same lesion. Cytologic samples were obtained by fine-needle aspiration, and histologic specimens were obtained via surgical biopsy, ultrasound-guided biopsy, or necropsy. RESULTS: Cytologic diagnoses corresponded with histologic diagnoses in 19 of 31 (61.3%) cases and differed in 5 of 31(16.1%) cases, and 1 aspirate was inadequate for evaluation. In 7 of 31 (22.6%) cases, histologic evaluation of tissue architecture was required to distinguish between reactive and neoplastic conditions. On the basis of histologic diagnosis in 14 animals with nonneoplastic conditions, the cytologic diagnosis was correct in 11 cases, not definitive in 2 cases, and incorrect in 1 case. In 17 animals with malignant neoplastic diseases, the cytologic diagnosis was correct in 8 cases, not definitive but consistent with possible neoplasia in 5 cases, and incorrect in 4 cases. Multiple similar-appearing nodules were significantly associated with malignancy, whereas single lesions were more often benign. CONCLUSIONS AND CLINICAL RELEVANCE: Ultrasound-guided aspiration of splenic lesions is a minimally invasive tool for obtaining specimens for cytologic evaluation. Although cytologic diagnoses often reflect histologic results, if missampling or incomplete sampling occurs or tissue architecture is required to distinguish between reactive and neoplastic conditions, accurate diagnosis with fine-needle aspiration may not be possible.     

Cutaneous lesions.

Although not a substitute for histologic examination, lumps, bumps, and lesions of the skin and subcutis readily lend themselves to cytologic examination via FNB, fine-needle nonaspiration biopsy, imprinting, or scraping of lesions. These techniques are used to obtain cells that can be examined by a clinical pathologist or cytologist to provide a diagnosis, decide a course of therapy, or offer a prognosis. Although histologic and cytologic examinations do not always agree, many times there is excellent correlation between the two disciplines. There are few patients with cutaneous lesions that would not benefit from cytologic examination of their lesion.     

Fine-needle aspiration biopsy of canine mammary gland tumours: a comparison between cytology and histopathology

In the current study, a total of 90 mammary neoplasms obtained from 55 female dogs were used to determine the accuracy of fine-needle aspiration cytology in the diagnosis of canine mammary tumours and to investigate the feasibility of this technique for the differentiation of simple tumours from complex or mixed tumours. Three aspirations were performed on each mammary gland mass using a 22-gauge needle attached to a 5-ml syringe before the mammary glands were surgically excised and submitted for histopathological examination. Twenty-five (27.7%) of 90 samples were classified as insufficient/inadequate for diagnosis. Of the remaining 65 samples, six (9.2%) were benign, 51 (78.5%) were malignant tumours and 8 (12.3%) were suspicious. Histopathological examination of the 90 specimens revealed five (5.6%) benign, 84 (93.3%) malignant and one (1.1%) non-neoplastic lesion. The diagnostic accuracy, sensitivity and specificity of cytologic examination for diagnosing malignancy were 96.5%, 96.2% and 100%, respectively. However, when inadequate (n = 25) and suspicious (n = 8) samples were included, the diagnostic accuracy and sensitivity decreased to 63.3% and 60.7%, respectively, but no change was observed in the specificity. Furthermore, it was not possible to differentiate simple tumours from complex and mixed tumours because spindle cells were seen in both 28% of the simple tumours and 39.3% of the complex or mix tumours. In conclusion, we believe that fine-needle aspiration cytology of canine mammary tumours is a valuable diagnostic tool, although our results indicated lower accuracy when inadequate samples were taken into consideration.     

Hypercalcemia associated with gastric pythiosis in a dog

A 20-month-old castrated male Labrador Retriever with a 3-month history of anorexia, weight loss, and vomiting was evaluated. Plasma biochemical abnormalities included marked hyperglobulinemia and hypercalcemia. Serum levels of parathyroid hormone, parathyroid hormone-related protein, 25-hydroxyvitamin D, and 1,25-dihydroxyvitamin D were either low or within reference intervals. Gastric wall thickening and abdominal lymphadenomegaly were observed with abdominal ultrasonography. Cytologic evaluation of a sample obtained via fine-needle aspiration of the gastric wall revealed pyogranulomatous inflammation and numerous poorly stained hyphae. Partial gastrectomy was performed, and a diagnosis of gastric pythiosis was made by immunohistochemical staining of infected gastric tissue, as well as by immunoblot serology. This case demonstrates that diagnostic samples for cytologic evaluation can be obtained by fine-needle aspiration of Pythium insidiosum-infected tissues and that a presumptive diagnosis can be made by examination of a Romanowsky-stained smear. Furthermore, pythiosis should be considered as a differential diagnosis for hypercalcemia, especially in young dogs with inflammatory lesions that have a granulomatous component. The mechanism for the hypercalcemia in this dog was not determined; however, calcium concentrations normalized after surgical resection of the gastric lesion.     

Computed tomography-guided fine-needle aspiration and tissue-core biopsy of bone lesions in small animals

In humans, free-hand computed tomography (CT)-guided biopsy is an accurate method to obtain a tissue sample. There are only a few reports of this technique in veterinary medicine. In the present study, 21 dogs and two cats underwent a free-hand CT-guided tissue-core biopsy (17 animals) or fine-needle aspiration (six animals) of a bone lesion. Two out of 17 tissue-core samples were also cultured. All 17 tissue-core biopsy samples were diagnostic (accuracy of 100%). Five out of six aspirates were diagnostic (accuracy of 83.3%). The overall accuracy was 95.7%. In one aspirate, cytologic quality was insufficient containing only blood. No major complications were encountered. Fourteen neoplastic, two infectious and six benign lesions were diagnosed. CT examination after intravenous contrast medium added useful information to avoid large vessels and to biopsy-viable tissue. Free-hand CT-guided tissue-core biopsy and aspiration appears to be a safe and very accurate procedure for use in the diagnosis of bone-associated diseases in small animals.     

Accuracy of ultrasound-guided fine-needle aspiration of the liver and cytologic findings in dogs and cats: 97 cases (1990-2000)

OBJECTIVE: To evaluate the accuracy of ultrasound-guided fine-needle aspiration of the liver and cytologic findings in dogs and cats. DESIGN: Retrospective study. ANIMALS: 56 dogs and 41 cats. PROCEDURE: Medical records of dogs and cats evaluated from 1990 to 2000 by use of cytologic and histopathologic examination of the liver were reviewed. Histologic and cytologic diagnoses were categorized as vacuolar hepatopathy, inflammation, neoplasia, cirrhosis, primary cholestasis, shunt, normal, and other. RESULTS: Overall agreement between the histopathologic diagnosis and cytologic diagnosis was found in 17 of the 56 (30.3%) canine cases and 21 of the 41 (51.2%) feline cases. Vacuolar hepatopathy was the category with the highest percentage of agreement. Vacuolar hepatopathy was identified via cytologic examination in 7 of 11 and 15 of 18 dogs and cats, respectively, in which histopathologic examination revealed that it was the predominant disease process. However, it was also the category that was most commonly misdiagnosed via cytologic examination. Inflammatory disease was accurately identified cytologically in 5 of 20 and 3 of 11 dogs and cats, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Acknowledging the limitations of cytology and the extent of discrepancies between cytologic and histopathologic findings in dogs and cats will help clinicians make better decisions in diagnosing liver disease.     

Contrast-enhanced power and color Doppler ultrasonography of the pancreas in healthy and diseased cats

Background: The diagnosis of feline pancreatic disease is difficult, because clinical abnormalities and routine noninvasive diagnostic tests are unreliable. Objective: The purpose of this study was to investigate by Doppler ultrasonography if vascularity and blood volume differs in the otherwise ultrasonographically normal and diseased feline pancreas. Animals: Thirty‐six client owned cats. Methods: The pancreas was examined with B‐mode and contrast‐enhanced color and power Doppler ultrasonography. Doppler images were analyzed with a computer program: parameter fractional area represents a vascularity index and color‐weighted fractional area assesses blood volume. Results: Based on the B‐mode findings, the pancreas was considered normal in 11 clinically healthy cats and diseased in 25 cats of which 4 were clinically healthy and 21 had clinical signs consistent with pancreatic disease. Histologic or cytologic samples were taken in all diseased pancreata. Fifteen samples were of diagnostic quality: purulent or mixed cellular inflammation (8), nodular hyperplasia (4), and neoplasia (3) were identified. Vascularity and blood volume for all Doppler methods was significantly higher in cats with pancreatic disease. Significantly higher Doppler values were detected with power Doppler than with color Doppler, and with postcontrast color and power Doppler than with precontrast Doppler technologies. Conclusion: Contrast‐enhanced Doppler ultrasonography appears feasible in the feline pancreas. Significant differences were found between normal cats and those with evidence of pancreatic pathology. Further studies are needed to evaluate its use for the differentiation of pancreatic disorders and in cats suspected to have pancreatic disease but without B‐mode ultrasonographic changes of the pancreas.     

Ultrasound-Guided Fine-Needle Aspiration of Focal Parenchymal Lesions of the Lung in Dogs and Cats

Ultrasound-guided fine-needle aspiration (FNA) of the lung was performed on 16 dogs and 3 cats with consolidated pulmonary lesions or masses identified on thoracic radiographs. The cytologic results from the FNA were confirmed by histopathology, response to treatment, or microscopic identification of Blastomyces organisms. Neoplasia was identified correctly by FNA cytology in 10 of 11 animals, and no false positive results occurred, yielding a positive predictive value of 100%. Of 8 animals with infectious disease, 5 of 6 had blastomycosis and 1 had a bacterial infection, based on cytologic evaluation. Eight animals required sedation for the procedure, and none had clinical complications. We conclude that ultrasound-guided FNA of pulmonary mass lesions is an inexpensive, safe, and accurate method for diagnosing blastomycosis or neoplasia, especially carcinomas, in dogs and cats.     

Organisms in an aspirate from an ulcerated mass: etiologic agent or mass‐querade?

Smears prepared from a fine-needle aspirate of an ulcerated, dermal mass between the digits of a 9-month-old Bull Terrier puppy revealed a moderately cellular, mixed-cell inflammation with numerous extracellular organisms. The organisms were 3-8 microm in length, curved to oval in shape, with prominent nuclei, and (retrospectively) a rare single, narrow-based bud. The cytologic diagnosis was mycotic dermatitis due to infection with an unusual yeast. Histologic sections of the lesion showed pyogranulomatous inflammation without evidence of an infectious organism. Contamination of the cytologic smears was suspected to have taken place in the clinical pathology laboratory and was confirmed by the isolation of a yeast with identical microscopic features from a cactus located on a windowsill near the work bench. The yeast was cultured and identified as Rhodotorula minuta, an airborne contaminant and ubiquitous saprophyte. It can be difficult to differentiate external contamination from infection when interpreting a cytologic specimen, however, it is important to do so, especially for unusual or opportunistic pathogens.     

Systemic infection with Geomyces organisms in a dog with lytic bone lesions

CASE DESCRIPTION: A 5-year-old neutered male mixed-breed dog was evaluated by a veterinarian because of a 4-week history of progressive lethargy and poor appetite; the dog was then examined at a referral hospital. CLINICAL FINDINGS: Hyperglobulinemia was identified via serum biochemical analyses performed before and after arrival at the hospital. Lysis of sternebrae 1 and 2 and sternal lymphadenopathy were detected radiographically. Fine-needle aspirates were collected from the affected sternebrae and lymph node for cytologic examination; findings were consistent with pyogranulomatous inflammation associated with fungal infiltrates. Geomyces organisms were identified via microbial culture of sternebral aspirates. TREATMENT AND OUTCOME: Treatment consisted of oral administration of itraconazole. After 6 months, remodeling of the affected sternebrae and resolution of sternebral lysis were evident radiographically. Geomyces organisms and pyogranulomatous infiltrates persisted despite clinical improvement. Treatment with itraconazole was continued for an additional 3 months. CLINICAL RELEVANCE: Infection with Geomyces organisms is typically localized to the skin and nail beds. In the dog of this report, systemic dissemination of Geomyces organisms resulted in lysis of the first 2 sternebrae. Cytologic examination of fine-needle aspirates and microbial culture of samples of the affected sternebrae were important diagnostic tests for successful identification of the organism. Despite 6 months of itraconazole administration and evidence of clinical improvement, fungal organisms persisted in the dog's affected sternebrae. Practitioners should include Geomyces infection among the differential diagnoses for suspected systemic mycosis and should perform cytologic examination and microbial culture of affected tissue throughout treatment of affected dogs.     

Liver aspirate from a Shar Pei dog

A 5-year-old, neutered male, Shar Pei dog was presented with weight loss, anorexia, lethargy, stranguria, and distal limb edema. Clinicopathologic abnormalities included anemia, an inflammatory leukogram, azotemia, icterus, urinary tract infection, and hepatomegaly with a markedly hypoechoic liver. Cytologic findings in a fine-needle aspirate of the liver included large amounts of amorphous, pink, extracellular matrix between hepatocytes. The amorphous material was congophilic using Congo red stain on a hepatic cytology specimen and green birefringent areas were observed under polarized light, confirming the presence of amyloid. The dog was euthanized and a necropsy was done. Histopathologic evaluation using H&E and Congo red staining confirmed amyloid deposits within the liver, kidneys, intestinal vessels, pancreas, and mesenteric ganglia. Immunohistochemical staining of liver and kidney sections using anti-AA amyloid and anti-P component antibodies confirmed the presence of AA amyloid. In this case, we demonstrated that Congo red staining and polarized light microscopy are a useful diagnostic technique in cytologic specimens of suitable thickness for confirming the presence of amyloid.     

Utility of diagnostic tests for and medical treatment of pulmonary blastomycosis in dogs: 125 cases (1989-2006)

OBJECTIVE: To compare results of the most common diagnostic tests for pulmonary blastomycosis in dogs, identify factors associated with outcome, and determine response to various antifungal treatment protocols. DESIGN: Retrospective case series. ANIMALS: 125 dogs with pulmonary blastomycosis. PROCEDURES: Medical records were reviewed, and information was obtained regarding diagnostic methods, results of routine laboratory testing, and radiographic response to antifungal treatment. RESULTS: 79 dogs survived, 38 died, and 8 were euthanized. Transthoracic fine-needle aspiration and transtracheal lavage were the most common diagnostic methods. Results of an agar gel immunodiffusion test for antibodies against Blastomyces dermatitidis were negative in 12 of 24 (50%) dogs. Only 3 of 94 (3.2%) dogs in which cytologic or histologic examination or bacterial culture of pulmonary samples were performed had any evidence of concurrent bacterial infection. The half-time for radiographic resolution of pulmonary infiltrates did not vary significantly with antifungal treatment, and use of a loading dosage of itraconazole was not associated with significant improvements in outcome or time to disease resolution. Dogs that died had a higher number of band neutrophils at initial examination, compared with those that survived. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that the agar gel immunodiffusion test should not be used as the sole diagnostic test for pulmonary blastomycosis in dogs, that concurrent bacterial pneumonia was uncommon in dogs with pulmonary blastomycosis, and that the rate with which pulmonary infiltrates resolved did not vary significantly among antifungal treatments.     

A "down under" lesion on the muzzle of a dog

A 10-year-old, castrated, male Labrador Retriever was presented to a local veterinary practice for investigation of a firm, deeply pigmented, alopecic, subcutaneous mass (8 mm in diameter) on the left side of the muzzle. A fine-needle aspirate of the mass was submitted for cytologic evaluation to the University of Florida. Microscopically, the preparation contained a predominant population of histiocytes that contained variable numbers of intracytoplasmic, negative-staining, filamentous structures consistent with Mycobacterium sp. A presumptive diagnosis of canine leproid granuloma syndrome was based on the cytologic findings and location of the lesion. Acid-fast staining revealed bright pink, acid-fast organisms within the histiocytic cells, supporting the diagnosis. The bacteria were not detected in histopathologic sections or by a polymerase chain reaction (PCR) test 1 week later, however, possibly because of spontaneous remission. Canine leproid granuloma syndrome is a common disease in Australia, but is uncommon in dogs in North America. It is caused by a novel, unnamed Mycobacterium species and usually affects the skin and subcutaneous tissues of the head and ears. A diagnosis usually can be made in Wright's-Giemsa and acid-fast-stained cytologic specimens; however, definitive diagnosis requires PCR testing at a specialized laboratory.     

Diagnostic Yield of Cytologic Analysis of Pericardial Effusion in Dogs

Background

Pericardial effusion cytology is believed by many to be of limited value, yet few studies have evaluated its diagnostic utility.

Objectives

To determine the diagnostic utility of cytologic analysis of pericardial effusion in dogs and to determine if consideration of additional data could improve the diagnostic yield.

Animals

Two hundred and fifty‐nine dogs with cytologic analysis of pericardial effusion performed between April 1990 and June 2012.

Methods

Electronic medical records from a university teaching hospital were retrospectively reviewed; signalment, complete blood count, serum biochemistry, cytologic analysis of pericardial effusion, and echocardiographic data were recorded. Cytology was classified as diagnostic (infectious or neoplastic) or nondiagnostic (hemorrhagic or other) and groups were compared with multiple Student''s t‐tests.

Results

Cytology was grouped as nondiagnostic (92.3%) or diagnostic (7.7%) and characterized as hemorrhagic (90%), neoplastic (4.6%), infectious (3.1%), or other (2.3%). Overall cytologic analysis of pericardial effusion diagnostic utility was 7.7% and increased to 20.3% if the effusion hematocrit (HCT) <10%; echocardiographic evidence of a mass did not result in a significant increase in the diagnostic utility.

Conclusions and Clinical Importance

The diagnostic utility of cytologic analysis of canine pericardial effusion is variable depending on the underlying etiology. In this group of dogs, the diagnostic yield of cytologic analysis was greater for pericardial effusion samples in which the HCT was less than 10%.     

Sensitivity and specificity of methods of assessing the regional lymph nodes for evidence of metastasis in dogs and cats with solid tumors

OBJECTIVE: To determine sensitivity and specificity of physical examination, fine-needle aspiration, and needle core biopsy of the regional lymph nodes for evidence of metastasis in dogs and cats with solid tumors. DESIGN: Case series. ANIMALS: 37 dogs and 7 cats. PROCEDURE: Regional lymph nodes were evaluated by means of physical examination (palpation), fine-needle aspiration, and needle core biopsy. Results were compared with results of histologic examination of the entire lymph node, the current standard. RESULTS: Tumors included 18 sarcomas, 16 carcinomas, 7 mast cell tumors, and 3 other tumors. Carcinomas were more likely to have metastasized to the regional lymph node (7/16 animals) than were sarcomas (2/18). Sensitivity and specificity of physical examination were 60 and 72%, respectively. Sensitivity and specificity of cytologic examination of fine-needle aspirates were 100 and 96%, respectively. Sensitivity and specificity of histologic examination of needle core biopsy specimens were 64 and 96%, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that fine-needle aspiration may be a sensitive and specific method of evaluating the regional lymph nodes in dogs and cats with solid tumors, because results correlated well with results of histologic examination of the entire lymph node. Physical examination alone was not a reliable method and should not be used to decide whether to aspirate or biopsy the regional lymph nodes.     

Sensitivity of Tru-cut and fine needle aspiration biopsies of liver and kidney for diagnosis of feline infectious peritonitis

BACKGROUND: The detection of typical lesions and feline coronavirus (FCoV) antigen in tissues is the only conclusive method for making a diagnosis of feline infectious peritonitis (FIP). A positive result using Tru-cut biopsy (TCB) and fine-needle aspiration biopsy (FNAB) has high diagnostic specificity, but information about the capacity of these techniques to correctly identify cats with FIP lesions is not available. OBJECTIVES: The diagnostic sensitivity of TCB and FNAB for detecting liver and kidney histologic lesions caused by FIP was evaluated. METHODS: TCB and FNAB specimens collected mainly at necropsy from 25 cats with FIP were analyzed. Diagnostic sensitivity was calculated on the basis of the number of false-negative and true-positive specimens, compared with the number of organs bearing histologic lesions of FIP. RESULTS: Diagnostic sensitivity was higher for hepatic TCB (64%) and FNAB (82%) than for renal (39% and 42%, respectively) procedures. A high percentage of renal cytologic and TCB specimens were inadequate. Combined analysis of TCB and FNAB specimens collected from the same organ increased the diagnostic sensitivity for liver (86%) and kidney (48%). The sensitivity of immunohistochemical/cytochemical analysis was low (11-38% depending on the technique), probably due to variable distribution of feline coronavirus in the lesions. CONCLUSION: Biopsy of liver and kidney can correctly identify FIP lesions. However, false-negative results or inadequate samples occur with moderate frequency, especially for immunochemical analysis. Diagnostic sensitivity may be increased when both TCB and FNAB specimens from the same organ are examined.