Histopathological Reports of Clinical Cases of Dog Skin Neoplasms
A neoplastic proliferation is an abnormal growth of tissues which develops in an uncoordinated and uncontrolled manner as a result of some unusual stimulus. It does not serve any useful purpose to the host rather proves to be harmful which varies according to the nature of neoplasms. It disturbs the normal physiological mechanisms of the body depending on its lodgment. Neoplasia involves some permanent tissue alterations, manifesting itself in the form of excessive tissue multiplication and can be transmitted through generations.
Materials and Methods
Materials for this investigation were collected from various veterinary hospitals located within Kolkata metropolis. The dogs presented with detectable growths in various parts of their bodies were studied carefully for any clinical abnormality. The complete details of the cases such as breed, age and sex along with anatomical positions of different detectable growths were recorded for further analysis.
Altogether, 136 neoplasms could be detected during the study period. The gross appearance of each tumor mass was recorded. Few pieces of tumor tissues were collected after biopsy. The tissues thus collected were kept in vials containing neutaral formal saline solution for histo-pathological examination in the laboratory.
Biopsied skin tissues were processed and stained by Haematoxylin and Eosin method as per the procedure described by Lilli (1954).
Selected skin tissues were taken and washed with formalin. Then the tissues were kept in automatic tissue processor in ascending order strength of alcohol (70%, 80%, 90%, 95%, absolute alcohol No. 1 and No. 2) for one hour in each. Then the tissues were passed in Xylene No. 1 and Xylene No. 2 each for one hour. They were then placed in xylol and paraffin mixture (equal parts) for one hour, then in paraffin No. 1 and No. 2 each for one hour. Then the tissues were blocked in paraffin. Sections were cut at 5 – 6 micron thickness. Glass slides were smeared in egg albumen and cut sections were mounted on the smeared glass slides over the hot water bath at 80oC. The mounted slides were air-dried and then put in Xylene No. 1 and No. 2 to remove the paraffin. The slides were passed twice through descending grades of alcohol (absolute alcohol No. 1 and No. 2, alcohol 95%, 90%, 60%, 70%) for 2 min to remove xylene. Then the slides were washed under running tap water for 2 min to remove the alcohol. The slides were put in haematoxylin solutions for about 15 min and then washed in running tap water. To remove excess of haematoxylin, the sections were given dips once or twice in acid-alcohol and then were washed thoroughly. After washing, the slides were dipped in eosin solution for about 30 sec. Then the slides were passed through 95% alcohol, absolute alcohol, absolute alcohol No. 1 and No. 2 and finally the sections were mounted over cover slip with the help of DPX mounted as examined under microscope.
In this study, Van Geison’s stain was also used against some sections for identifying myoepithelial cells which appeared brownish-yellow.
Histopathological Examinations and Diagnosis
Histopathological changes of ten clinical cases suffering from skin neoplasia have been presented here as had been examined under the compound microscope at Department of Veterinary Pathology, WBUAFS.
Case No. 1
An Alsatian dog about 12 years old was suffering from multiple tumors on its flank region. Nodular shaped tumor was ulcerated, reddish-brown with areas of haemorrhages and yellow areas of necrosis.
Histological examination: Consisted of interwoven bundles of immature fibroblasts and moderate numbers of collagenous fibres. Hyperchromatic nuclei with disintegrated cytoplasmic area hemorrhage and edema were seen.
Case No. 2
A 9-year old Alsatian dog was showing a tumor in the neck region. It was 3 cm in diameter, ovoid, moderately firm, reddish black in color. There was bleeding from cut surface.
Histological examination: It reveals elongated neoplastic cells with hyperchromatic nuclei. Macrophage was filled with haemisiderin. Endothelial cells were present in vascular space along with thrombi, haemorrhage and necrosis.
Case No. 3
An ulcerated cauliflower like growth was found on the toes of an 11-years Spitz dog.
Histological examination: Revealed squamous cells arranged in cords or whorls with keratinized centres. Mitotic figures were seen. Cytoplasm was eosinophilic and nucleus was pyknotic. Concentric layers of squamous cells showed gradually increasing keratinization towards the centre-horn pearls.
Diagnosis: Squamous cell carcinoma.
Case No. 4
An 8-year old Cocker Spaniel dog showed a cystic growth on neck region. The tumor was firm and well demarcated. The growth was 3 cm in diameter. The upper surface was ulcerated. Cut surface was grayish-white in color.
Histological examination: The nuclei were embedded in a symplematic mass of poorly defined cell boundaries. Mitotic figures were seen.
Diagnosis: Basal cell epithelioma.
Case No. 5
An 11-years old French Poodle on clinical observation showed nodular growth on head. The area was hairless with a firm mass. The mass was 1 cm in diameter.
Histological examination: Revealed that tumor was composed of predominantly active mitotic generative cells of sebaceous glands. Single cells showed lipid vacuoles representing the start of differentiation foci with squamous epithelium and keratinization, which represented areas of differentiation towards sebaceous gland structure.
Diagnosis: Sebaceous adenoma.
Case No. 6
A 10-year old Grey Hound dog developed a firm bulging ring around the anus. Cut surface was tan and lobulated with red mottling.
Histological examination: Adenomas appear as lobules or cords of large, discrete, round to polyhedral cells with abundant finely granular acidophilic cytoplasm. Mitotic figures were rare.
Diagnosis: Perianal adenoma.
Case No. 7
A cross bred 9-years old Alsatian bitch developed a reddish-black growth on left fore leg. The ovoid shaped growth was 3 cm in diameter and blood was oozing out from cut surface.
Histological examination: Hemorrhages, endothelial cells in vascular spaces. Thrombosis in vascular channels. Presence of hyalinization in connective tissues was evidenced.
Case No. 8
An 11-years old cross bred healthy dog was suffering from tumor on the base of tail. There was soft cauliflower appearance having a broad base, foul smelling growth with overlying skin.
Histological examination: There was proliferation of cells of stratum germinatum. Basal cell layer was thickened. Infiltrating prickle cell layers in different strata were present. Keratohyaline deposition formed pearl shape. Mitotic figures were numerous. Infiltration of macrophages, plasma cells and lymphocytes was found. Anaplastic cells took an elongated splindle shape.
Diagnosis: Squamous cell carcinoma.
Case No. 9
A 10-year old Black Spaniel dog showed a broad base encapsulated firm mass having no hair on overlying skin on head.
Histological examination: Down growth of epithelial cells arranged in columns was observed which descended to dermis. Epithelial cells were club-shaped and have centrally and longitudinally arranged cells with peripheral palisading columns of cells in each club. Hyperchromatic nuclei arranged in sheets with plentiful connective tissue stroma were observed.
Diagnosis: Basal cell epithelioma.
Case No. 10
An 11-years old Spitz dog developed an easily movable firm mass underlying skin on the left eyelid. The area was hairless and ulcerated.
Histological examination: It consisted of irregular lobular formation. Basal cells were large with pleomorphic muclei vacuolation and eosinophilic cytoplasm was seen. Focal areas of keratinization were present.
Diagnosis: Adenocarcinoma of sebaceous glands.
In the present study it was found on the basis of gross and histopathological studies that skin neoplasms were composed of fibrosarcoma, haemangiosarcoma, squamous cell carcinoma, basal cell epithelioma, sebaceous adenoma, perianal adenoma and adenocarcinoma of sebaceous glands.
The first cum corresponding author, Dr. Sunit Kumar Mukhopadhayay is thankful to Dr. Subha Ganguly & Dr. Indira Paul who have immensely supported him in preparation of this manuscript, both of them being the co-authors of this article.