ABSTRACT OF THE WEEK

Journal of the American Animal Hospital Association
Volume 59 | Issue 1 (January 2023)

Clinical Utility of Cytology from Preoperative Percutaneous Fine Needle Aspirates of Solitary Liver Masses in 220 Dogs: A Retrospective Study (2009-2019).

J Am Anim Hosp Assoc. January 2023;59(1):12 - 19.

Megan Cray¹, Jessica Hokamp², Brittany Abrams³, Brian D Husbands⁴, Janet A Grimes⁵, Hadley Gleason⁶, David McChesney⁷, Sue A Casale⁸, Laura Elizabeth Selmic⁹

¹ From the Department of Surgery, Angell Animal Medical Center, Jamaica Plain, Massachusetts (M.C., D.M., S.A.C.).; ² From the Department of Veterinary Biosciences (J.H.), College of Veterinary Medicine, Ohio State University, Ohio.; ³ From the Department of Veterinary Clinical Sciences (B.A., L.E.S.), College of Veterinary Medicine, Ohio State University, Ohio.; ⁴ From the Department of Veterinary Clinical Sciences, College of Veterinary Medicine, University of Minnesota, St. Paul, Minnesota (B.D.H.).; ⁵ From the Department of Surgery, College of Veterinary Medicine, University of Georgia, Athens, Georgia (J.A.G.).; ⁶ From the Department of Veterinary Clinical Medicine, University of Illinois Urbana Champaign, Urbana, Illinois (H.G.).; ⁷ From the Department of Surgery, Angell Animal Medical Center, Jamaica Plain, Massachusetts (M.C., D.M., S.A.C.).; ⁸ From the Department of Surgery, Angell Animal Medical Center, Jamaica Plain, Massachusetts (M.C., D.M., S.A.C.).; ⁹ From the Department of Veterinary Clinical Sciences (B.A., L.E.S.), College of Veterinary Medicine, Ohio State University, Ohio.

Abstract

When a solitary liver mass is identified in a dog, a fine-needle aspirate (FNA) is commonly employed to attempt to obtain a diagnosis. Little information is provided in the literature evaluating the sensitivity/specificity of FNA cytology for solitary liver masses. We hypothesized that liver lesion size nor the presence of cavitation would impact the success of cytological diagnosis. Medical records were obtained for 220 client-owned dogs. Inclusion criteria included preoperative abdominal imaging, percutaneous FNA of a solitary hepatic mass with cytologic interpretation by a board-certified pathologist, and a surgical biopsy or mass excision yielding a histopathological diagnosis. Six dogs (2.7%) experienced a complication after FNA, none considered severe. The agreement rate for correct cytologic diagnosis was 22.9% (49/220). Of the neoplastic masses 18.9% (35/185) were correctly diagnosed via cytology. The overall sensitivity was 60%, and the specificity was 68.6%. Neither institution (P = 0.16), lesion size (P = 0.88), cavitation (P = 0.34), or needle gauge (P = 0.20) had an association with correct diagnosis. This study demonstrates that, although there is a low risk of complications following FNA of a hepatic mass, overall success rate for correct cytologic diagnosis based on FNA was low compared to histopathologic diagnosis.

Companion Notes

Retrospective report on the clinical utility of cytology of preoperative percutaneous fine needle aspirates of solitary liver masses in 220 dogs

Introduction on the diagnosis of solitary liver masses

- overall, primary hepatic tumors have a uncommon prevalence in the dogs

- fine needle aspirate (FNA) is commonly used to try to obtain a diagnosis

(before a biopsy with histopathology)

- gold standard for diagnosis is histopathology

- little in the literature on the sensitivity/specificity of FNA cytology

- in 1 study on diagnosis of liver disease

- overall agreement between histopathology and cytology assessed

- agreement found in 17 of the 56 (30.3%) dogs

- 14 of the 56 dogs had diffuse liver neoplasia or a defined mass

- in 2 of the 14 cases, cytology correctly identified neoplasia

- in another study comparing liver cytology to biopsy in 25 dogs and 31 cats

- complete agreement found in 34 (61.7%) animals

- in a 3^rd study comparing cytology and histology of focal liver lesions in dogs

(ultrasound (US)-guided FNA cytology)

- lesions were defined as either single or multiple focal lesions on US

(with identifiable margins)

- 30 of the 140 lesions were neoplastic

- sensitivity of cytology for neoplastic lesions: 52%

- in human medicine, in 1 large retrospective study of 713 liver aspirates

- overall sensitivity in diagnosing metastatic and primary malignancies: 93.4%

- overall specificity in diagnosing metastatic and primary malignancies: 96.7%

Study design

- study population:

- 220 dogs with a solitary hepatic mass

- inclusion criteria

- preoperative abdominal imaging: ultrasonography (US) or CT

(presence of singular mass based on radiologist’s description)

- all dogs had an abdominal US; 111 dogs had an abdominal CT

- percutaneous FNA of a solitary hepatic mass with cytologic interpretation

- by board-certified pathologist

- surgical biopsy or mass excision yielding a histopathological diagnosis

- history and signalment

- median age at surgery: 11.0 years of age with a range of 6.0-16.0

- median weight: 24.4 kg with a range of 3.0-50.6 kg

- median body condition score: 5.0 with a range of 2.0-9.0

- breeds represented by more than 5 cases

- mixed, 68 cases (30.9%)

- golden retriever, 23 cases (10.5%)

- Labrador retriever, 23

- shih tzu, 8

- Siberian husky, 7

- Scottish terrier, 6

- miniature schnauzer, 6

- procedure: records from 1/1/09 and 1/1/19 retrospectively reviewed

Results

- complications after FNA

- occurred in 6 dogs (2.7%); none considered severe or required surgery

- all FNAs performed under US guidance

- mild to moderate hemorrhage after FNA, 5

- hemoabdomen, 1

- agreement rate for correct cytologic diagnosis: 22.9% (49/220)

- of neoplastic masses 18.9% (35/185) were correctly diagnosed via cytology

- diagnostic utility

- overall sensitivity: 60%

- specificity: 68.6%

- the following had no association with a correct diagnosis

- institution

- lesion size

- largest median dimension on CT: 10.0 cm

- largest median dimension on ultrasonography: 7.9 cm

- cavitation, present in 77.7% of cases

- needle gauge (unknown in 25%)

- 22 gauge used in 40% of cases

- 25 gauge used in 34.1% of cases

- histopathology

- 185 (84.1%) were considered to be neoplastic

- 35 (15.9%) were considered benign

- most common histopathologic diagnoses

- hepatocellular carcinoma, 125/220 (56.8%)

- 32 (25.6%) correctly identified on FNA:

- 58 (46.4%) correctly identified as neoplastic on FNA

- hepatocellular adenoma, 27/220 (12.3%)

- 0 correctly identified on FNA

- 14 correctly identified as neoplastic on FNA

- hepatocellular hyperplasia, 10/220 (4.5%)

- 1 correctly identified on FNA

- compiled diagnoses of the 220 liver masses

- hepatocellular carcinoma, 125 cases

- hepatocellular adenoma, 27cases

- hepatocellular hyperplasia, 10

- hepatocellular vacuolation,6

- hepatitis, 5

- biliary cystadenocarcinoma, 4

- hepatic abscess, 4

- hemangiosarcoma, 3

- adenocarcinoma, 3

- hematoma, 3

- hepatocellular carcinoma + adenoma, 3

- sarcoma, 3

- biliary cystadenoma, 2

- biliary adenocarcinoma, 2

- cholangiocarcinoma, 2

- fibrosarcoma, 2

- fibrosis, 2

- hepatic neoplasia, 2

- necrosis, 2

- biliary cyst, 1

- carcinoma, 1

- epithelial neoplasia, 1

- hepatocellular carcinoma + bile duct carcinoma, 1

- liposarcoma, 1

- malignant mixed tumor, 1

- peliosis hepatitis, 1

- round cell neoplasia, 1

- telangiectasia, 1

- histiocytic sarcoma, 1

“The findings in this study indicate that, although there is a low risk of complications following an FNA of a solitary hepatic mass, the overall success rate for correct diagnosis based on FNA cytology was low (22.9%; 49/220).”

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