Canine eyelid granular cell tumor: a report of eight cases

Blepharitis and Neoplasms of the Canine Eyelid Margin and Skin

Canine eyelid masses (tumors) should include the differential clinical diagnoses of neoplasia and blepharitis. They have many common clinical signs including tumor, alopecia, and hyperemia. Biopsy and histologic examination remains the most effective diagnostic test to establish a confirmed diagnosis and appropriate treatment. Neoplasms are typically benign (tarsal gland adenomas, melanocytomas, and so forth) with the exception of lymphosarcoma. Blepharitis is noted in 2 age groups including dogs aged less than 1.5 years and middle aged to older dogs. Most blepharitis cases will respond to specific therapy once an accurate diagnosis is established.

Predominance of Granular Cell Tumours among Testicular Tumours of Rabbits (Oryctolagus cuniculi f. dom.)

Testicular neoplasms are reported rarely in pet and laboratory rabbits (Oryctolagus cuniculi f. dom.), with interstitial cell tumours being the most commonly described testicular neoplasm. In this retrospective study, paraffin wax-embedded testicles with neoplastic changes from 52 rabbits were investigated. Five out of 52 animals exhibited more than one tumour type, resulting in a total of 57 tumours. Granular cell tumours were the most prevalent neoplasm with 36 examples (63%) out of the 57 testicular tumours. Interstitial cell tumours, Sertoli cell tumours and seminomas occurred less frequently. Granular cell tumours of the testis are rare in rabbits. Histological similarities between granular cell and interstitial cell (Leydig cell) tumours in haematoxylin and eosin-stained tissue sections may lead to misdiagnoses. The periodic acid-Schiff reaction or immunohistochemistry for periaxin and S100 protein, as well as ultrastructural analysis, are useful methods to confirm the diagnosis.

First report of canine mammary gland granular cell tumour: case description and review of the literature

The case of a 5-year-old intact female Pitbull Terrier with a granular cell tumour (GCT) of the mammary gland is presented. The dog was admitted for surgical removal of a non-painful lump assumed to be a fibroadenoma. Histological and immunohistochemical findings leading to the diagnosis consisted of polygonal tumour cells with well-defined cell borders and granular cytoplasm, staining positively with neuron-specific enolase (NSE) and protein S100 and negatively for cytokeratin AE1-AE3. Some important points in the diagnostic and therapeutic approach to this uncommon neoplasm are discussed. To our best knowledge this is the first case of such tumour in the mammary gland described in the veterinary literature.

The Origin and Role of Autophagy in the Formation of Cytoplasmic Granules in Canine Lingual Granular Cell Tumors

Granular cell tumors (GCTs) are histologically characterized by polygonal neoplastic cells with abundant eosinophilic cytoplasmic granules. In humans, these cells are considered to be derived from Schwann cells, and the cytoplasmic granules are assumed to be autophagosomes or autophagolysosomes. However, the origin and nature of the cytoplasmic granules in canine GCTs have not been well characterized. The present study examined 9 canine lingual GCTs using immunohistochemistry, transmission electron microscopy (TEM), and cell culture and xenotransplantation experiments. In some cases, the tumor cells expressed S100, CD133, and desmin. The cytoplasmic granules were positive for LC3, p62, NBR1, and ubiquitin. TEM revealed autophagosome-like structures in the cytoplasm of the granule-containing cells. The cultured GCT cells were round to spindle shaped and expressed S100, nestin, Melan-A, CD133, LC3, p62, NBR1, and ubiquitin, suggesting that they were of neural crest origin, redifferentiated into melanocytes, and exhibited upregulated autophagy. The xenotransplanted tumors consisted of spindle to polygonal cells. Only a few cells contained cytoplasmic granules, and some had melanin pigments in their cytoplasm. The xenotransplanted cells expressed S100, nestin, Melan-A, and CD133. P62 and ubiquitin were detected, regardless of the presence or absence of cytoplasmic granules, while LC3 and NBR1 were detected only in the neoplastic cells containing cytoplasmic granules. These findings suggest that some xenotransplanted cells redifferentiated into melanocytes and that autophagy was upregulated in the cytoplasmic granule-containing cells. In conclusion, canine lingual GCTs originate from the neural crest and develop cytoplasmic granules via autophagy. In addition, the microenvironment of GCT cells affects their morphology.