Canine cutaneous clear cell adnexal carcinoma: histopathology, immunohistochemistry, and biologic behavior of 26 cases.

Thirty tumors including 27 distinctive cutaneous neoplasms and 3 metastatic tumors from 26 dogs were collected from diagnostic submissions to 3 laboratories. Characteristic histopathologic features included location in the subcutis or dermis (or both); lobular, nodular, and nest-like architecture; and a component of epithelioid cells with clear cytoplasm. Additional features present in most cases included follicular dermal papilla-like structures, low mitotic index, nuclear pleomorphism, necrosis, and mineralization. Cytoplasmic periodic acid Schiff-positivity, which was abolished by pretreatment with diastase, indicated the presence of glycogen in all cases. The oil red O stain did not demonstrate cytoplasmic lipid. Melanin granules, accentuated by the Fontana-Masson method, were observed infrequently. A sparsely cellular mucinous stroma and stromal cartilaginous differentiation were uncommon. By immunohistochemistry, neoplastic cells stained positively for cytokeratin (29 of 29), vimentin (28 of 28), S-100 protein (24 of 29), and melan A (8 of 12); results were negative for smooth muscle actin and calponin in all cases. Clinical follow-up information was obtained on all 26 dogs. One tumor recurred, 1 metastasized to a regional lymph node, and 1 metastasized to regional lymph nodes twice. In another case, possible pulmonary metastasis was noted radiographically. The findings are consistent with a poorly differentiated, low-grade, adnexal carcinoma of the skin. Similar canine cutaneous neoplasms have been reported as "clear-cell hidradenocarcinoma" and "follicular stem cell carcinoma." The authors propose the designation "cutaneous clear cell adnexal carcinoma."     

Canine eyelid granular cell tumor: a report of eight cases

To describe a previously unreported neoplasm of the medial canthus and eyelid in dogs. Clinical and pathologic features of granular cell tumors in the dog were reviewed. Granular cell tumors, arising from the medial canthal eyelid of eight dogs, were identified from the archives of the Comparative Ocular Pathology Laboratory of Wisconsin (COPLOW). The affected dogs ranged in age from 5 to 12 years (mean of 9.25 years). Follow‐up information was available for seven of the eight cases. The clinical presentation included swollen hyperemic lids (4/8), ulcerated skin overlying the mass (2/8), and red conjunctiva (7/8). All eight of the cases had firm masses extending from the palpebral conjunctiva to the eyelid margin at the medial canthus. Histologically, the tissue was composed of a highly collagenous neoplastic growth. The neoplastic cells were oval to strap‐like cells with an oval bland appearing nucleus and abundant amounts of granular cytoplasm with very distinct cell boundaries. These granular cells were embedded in a dense collagen matrix. A PAS stain faintly highlighted the granular appearance of the neoplastic cells, which is a defining characteristic of this tumor. There was no recurrence in the seven cases available for follow‐up. Canine granular cell tumors of the medial canthus present clinically and histologically as a benign neoplasm. Granular cell tumors have a characteristic histological appearance. Granular cell tumors should be on the differential list for nodules of the medial canthus in dogs.     

Canine cutaneous epitheliotropic T‐cell lymphoma: a review of 30 cases

This retrospective study reviewed the clinical, histological and immunohistochemical features of 30 European cases of canine cutaneous epitheliotropic T‐cell lymphoma (CETL). The clinical presentation was highly variable and was not associated with the disease subtype. Diffuse erythema (86.6%) with scaling (60%) and focal hypopigmentation (50%) were the most common lesions. The skin was uniformly involved but muco‐cutaneous junctions or mucosae were affected in 50% of cases. The median age at diagnosis was 10 years (SD 2.79, range 4–15) and the median time between onset and final diagnosis was 5 months (SD 3.79, range 0–12). Five cases occurred in Bichon Frises. There was no evidence of a previous history of chronic dermatitis in any cases. Histologically, the follicular epithelium was affected in 86.7% of cases. One case with mainly follicular disease was considered folliculotropic mycosis fungoides (MF), but no follicular mucinosis was observed. Epidermal Pautrier’s microabscesses were uncommon (23.3%). Sweat glands were infiltrated in 70% of cases. Immunohistochemistry confirmed T‐cell neoplasia in all cases. B cells infiltrated as individual cells or formed linear bands or ectopic follicles at the base of the neoplasm. Ki67 labelling revealed a range of proliferation indices but did not correlate with severity. A final diagnosis of classical MF was made in 40% of the dogs, MF d’emblé in 36.7%, generalized Pagetoid reticulosis in 20% and localized Pagetoid reticulosis in one case (Woringer–Kolopp Pagetoid reticulosis). The median survival time after diagnosis was 6 months and this did not change appreciably with therapy (lomustine or prednisolone).     

Canine cutaneous epitheliotropic T‐cell lymphoma: a review

Cutaneous epitheliotropic T‐cell lymphoma in the dog is a rare neoplastic condition with unknown aetiology. The dermatitis is characterized by infiltration of neoplastic T lymphocytes with a specific tropism for the epidermis and the adnexal structures. The different clinical and histological forms (mycosis fungoides, pagetoid reticulosis and Sézary syndrome) are reviewed. The disease in the dog resembles the human syndrome, but in 80% of the canine cases, neoplastic cells are CD4^?/CD8⁺ versus CD4⁺/CD8^? in 90% of the human patients. Prognosis is poor with a survival time from few months to 2 years. Treatments frequently have a low efficacy. New protocols using lomustine may improve the poor prognosis of the disease.     

Canine inflamed nonepitheliotropic cutaneous T‐cell lymphoma: a diagnostic conundrum

Background –  Cutaneous T‐cell lymphoma (CTCL) in dogs is a heterogeneous disease complex, which consists of nonepitheliotropic (NE) and epitheliotropic forms. These lymphomas are readily recognized by the presence of dominant populations of cytologically atypical lymphocytes. Objective –  The objective of this study was to introduce the key features of inflamed NE‐CTCL, which is easily confused with reactive, inflammatory histiocytic disease. Animals –  Twenty‐four dogs (mean age 7.5 years) presented with inflamed NE‐CTCL. Lesions presented as nodules, plaques or masses. An initial diagnosis of cutaneous reactive histiocytosis (11 dogs) or histiocytic neoplasia (three dogs) was made by primary pathologists. Methods –  Lesions were assessed by histology and immunohistochemistry to detect canine leukocyte antigens. Lesional genomic DNA was extracted and gene rearrangement analysis of the T‐cell receptor γ locus was assessed. Results –  The cutaneous lesions consisted of pleocellular infiltration of the dermis with variable extension into the subcutis. The lesions often surrounded vessels and adnexae. Epitheliotropism was minimal or lacking. Small lymphocytes, plasma cells and intermediate to large, cytologically atypical lymphocytes were scattered between prominent histiocytic infiltrates. Atypical lymphocytes often had marked variation in the intensity of CD3 expression. Molecular clonality analysis of the T‐cell receptor γ locus revealed clonal expansion of T cells in 22 of 23 dogs tested. Conclusion –  The recognition of inflamed NE‐CTCL and its differentiation from cutaneous reactive histiocytosis depends on careful assessment of lymphocyte morphology and immunostaining patterns. Confirmation of the diagnosis is best accomplished by T‐cell antigen receptor gene rearrangement analysis.     

Canine granular cell tumour (myoblastoma): a report of four cases and review of the literature

Four cases of canine granular cell tumour (myoblastoma) were diagnosed at the Washington Animal Disease Diagnostic Laboratory between 1977 and 1981. Two of the tumours occurred in the tongue, one in the lip and one in the larynx. Three cell types were found in the tumours. Granular cells, with abundant periodic acid-Schiff (PAS)-positive cytoplasmic granules, were most numerous. Interstitial cells resembled fibroblasts and were often adjacent to collagen fibrils. Angulate body cells contained PAS-positive, ovoid cytoplasmic inclusions composed of microtubular subunits. Review of these and reported cases indicates no breed or sex predisposition for this rare tumour. The tongue is the most common site and all but one tumour have occurred in or adjacent to the oral cavity. There have been no reports of recurrence or metastasis of granular cell tumours except the recurrence of a disputed case in the subcutis of a dog.     

Canine adrenocortical atrophy: review of literature and a report of two cases

Primary adrenocortical atrophy is reported in a 3-year-old female Gordon Setter and a 2-year-old spayed female German Shepherd dog.
Résumé. On rapporte un cas d'atrophie adréno-corticale primaire chez une chienne Gordon Setter de trois ans et un autre chez une femelle castrée de la ram Berger Allemand, âgée de deux ans.
Zusammenfassung. Primäre adrenocorticale Atrophie wurde bei einer dreijährigen Gordon-Setter Hündin und einer zweijahrigen kastrierten Schaferhündin festgestellt.     

Canine lobular orbital adenoma: a report of 15 cases with distinctive features

Objective To describe a unique orbital neoplasm in dogs, of lacrimal or salivary gland origin. Animals studied Fifteen dogs with lesions consistent with a diagnosis of lobular adenomas involving the orbit were identified from the Comparative Ophthalmic Pathology Laboratory of Wisconsin from 1994 to 2001. Results The neoplasm occurred in nine females and six males. Affected dogs ranged in age from 7 to 17 years (mean = 9.7 years). Follow‐up information was available for 13 of the 15 cases. The clinical presentation included swollen/hyperemic eyelids (4/15), third eyelid protrusion (3/15), conjunctival mass (6/15), exophthalmos (4/15), resistance to retropulsion (2/15), or strabismus (1/15). In 13 cases the masses were composed of nodular, friable tissue and they were solid in two cases. Histologically, the tissue was found in encapsulated lobules resembling well differentiated lacrimal or salivary glands but completely lacking ducts. Granular PAS‐positive material was found within the cytoplasm. There was recurrence in 10 of the 13 cases available for follow‐up. Of those cases in which enucleation or exenteration was performed (3/15), there was recurrence of disease in one case. In three cases the dogs were euthanized before recurrence at 3 months, 5 months and 3 years post surgery. None of the deaths was related to the tumor. Conclusion In the 15 cases reviewed, lobular adenomas of the orbit presented clinically and histologically as a benign neoplasm of lacrimal or salivary gland origin. Recurrence was likely unless the mass was completely excised, at times requiring orbital exenteration.     

Canine eosinophilic folliculitis and furunculosis in three cases

The historical, clinical and histopathological features of three dogs with eosinophilic folliculitis and furunculosis are described. The disease was characterised by the rapid development of pruritic, papular, pustular and ulcerative lesions on the dorsum of the muzzle. Skin lesions were confined to the face in two cases. The third dog had more generalised pustular lesions. Skin biopsy specimens showed marked eosinophil infiltration particularly centred on pilosebaceous units. Dermal collagen necrosis was evident in two cases. Similar facial lesions have previously been described as ‘nasal pyoderma’. The three dogs failed to respond to initial antibacterial therapy but showed a rapid clinical response when prednisolone was given orally at doses ranging from 1 to 2-2 mg/kg, in addition to the antibacterial therapy, suggesting that glucocorticoids are indicated for the treatment of eosinophilic folliculitis and furunculosis. The aetiology of the disease was not determined.     

Canine paraganglioma: a case report

An 8-year-old castrated Cocker Spaniel with tympanic paraganglioma was presented. The tumour was resected twice with an interval of 120 days. The dog presented with tetraparesis 130 days after the second operation and had radiologic evidence of metastasis to the C5 vertebra. On pathologic examination, metastasis of the tumour was found in the myocardium, lungs, kidney, and C5 vertebra. The tumour, which is being described for the first time in the dog, was highly vascular, and was characterized by various-sized groups of medium-sized cells separated by vascular stroma. The neoplastic cells were round or polyhedral with moderately hyperchromatic nuclei, scattered chromatin, indistinct nucleoli, and eosinophilic granular cytoplasm. The metastatic lesions were histologically similar to the primary tumour.     

Partial colonic obstruction following ovariohysterectomy: a report of three cases

Partial extramural obstruction of the descending colon was diagnosed in two dogs and a cat as a complication of elective ovariohysterectomy. In each case, the obstruction was caused by fibrous tissue that encircled or crossed the descending colon, severely restricting the organ's normal mobility and luminal diameter. Clinical signs secondary to obstipation were observed in two cases, five weeks and 27 months after elective ovariohysterectomy. In one dog without clinical signs, the adhesion was an incidental finding during a laparotomy performed nine years after the ovariohysterectomy. The fibrous adhesions were removed surgically in all three cases without additional complications.