Gastric mucinous adenocarcinoma with cutaneous metastases in a dog: diagnosis by fine-needle aspiration cytology

Retrospective study of canine cutaneous tumors in Japan, 2008-2017

Cutaneous tumors are commonly found in dogs. To date, few studies have investigated the epidemiology of canine cutaneous tumors in Asian countries. The present study aims to report the prevalence of canine cutaneous tumors in Japan, and assess the association of breed, age, sex, and anatomical locations with the development of common tumor types. A total of 1,435 cases of cutaneous tumors were examined, of which 813 (56.66%) cases were malignant, and 622 (43.34%) were benign. Soft tissue sarcomas (18.40%), mast cell tumor (16.24%), lipoma (9.69%), hair follicle tumors (9.34%), and benign sebaceous tumors (8.50%) outnumbered the other tumor types. Tumors were commonly found on the head (13.87%), hindlimb (10.52%), forelimb (8.01%), chest (5.78%), and neck (5.57%). The risk of developing cutaneous tumors increased significantly in dogs aged 11-year and above (P<0.001). Mixed-breed dogs (14.63%), Miniature Dachshund (9.90%), and Labrador Retriever (8.01%) were the three most presented breeds; while Boxer, Bernese Mountain Dog, and Golden Retriever had an increased risk of cutaneous tumor development in comparison to mixed-breed dogs (P<0.05). Epidemiological information from the present study will serve as a useful reference for regional veterinarians to establish a preliminary diagnosis of canine cutaneous tumors.

Use of destained cytology slides for the application of routine special stains

BACKGROUND

Special stains to demonstrate microorganisms or intra- and extracellular substances have not been evaluated in detail regarding their applicability and usefulness in destained cytologic specimens.

OBJECTIVES

The aim of this study is to compare the results of routine special stains on destained slides previously stained with Hemacolor and on fresh (unstained) specimens.

METHODS

Archival Hemacolor-stained fine needle aspirate specimens of inflammation with infectious agents (bacterial, mycobacterial, and fungal infections), neoplasia (melanoma, myxosarcoma, and mammary adenocarcinoma), and hemorrhage (pericardial effusion) from 14 dogs and 7 cats were selected. Cells in a minimum of 4 fields were photographed and 5 slides from each case were then destained by different methods (alcohol acid or microwave). Seven special stains were applied selectively to the destained slides, depending on the cytologic findings: periodic acid Schiff, Grocott-Gomori methenamine silver, Gram's, Ziehl-Neelsen, Alcian blue, Fontana-Masson, and Prussian blue. The same fields were rephotographed and 2 observers evaluated the slides qualitatively, with comparison to fresh cytologic specimens from similar lesions.

RESULTS

Special stains applied to destained slides demonstrated the expected cellular and extracellular material or organisms independent of the destaining method. Staining intensity, nonspecific staining (background), cell morphology, and nuclear counterstaining results were similar to those of special stains applied to fresh unstained slides.

CONCLUSIONS

Destaining does not appear to affect the results of routine special staining for cytologic specimens. Destaining before special stains may be a valuable diagnostic strategy when few slides are present or only stained slides are available.