Canine conjunctival mast cell tumors: a retrospective study

Eyelid and conjunctival mast cell tumors: A retrospective study of 26 dogs and 8 cats

OBJECTIVE

The objective of the study was to describe clinical and histologic characteristics of eyelid (LMCT) and conjunctival (CMCT) mast cell tumors in dogs and cats presented to a referral clinic in Germany.

ANIMAL STUDIED

Medical records were reviewed to identify dogs and cats diagnosed with LMCTs or CMCTs between 2006 and 2020.

RESULTS

LMCT were diagnosed in 31 patients and were cutaneous (n = 28; 20 dogs and 8 cats) or subcutaneous (three dogs). Five cases involved the mucocutaneous junction (four dogs, one cat). CMCTs occurred only in dogs (n = 3). At the time of presentation two of the four canine LMCT cases involving the mucocutaneous junction had metastasized to a mandibular lymph node. When applying the Kiupel system, both these cases were categorized as high grade. 85.7% (18/21) of the canine (19 cutaneous and 2 subcutaneous) LMCT and all CMCT cases were categorized as Kiupel low grade. No local recurrences occurred in all LMCT cases in which clean surgical margins were obtained (n = 18, mean surgical margin width: dogs 9.4 mm, cats 3.8 mm). Two cats (2/4) and four dogs (4/7) with questionable or incomplete surgical margins experienced local recurrences (mean time to recurrence of 180 and 637 days in dogs and cats, respectively).

CONCLUSION

Recurrence of low-grade LMCTs and CMCTs following excision with clean margins is rare. Tumors involving the mucocutaneous junction may be of higher grade and prone to lymphatic metastasis.

Weishaar's classification system for nodal metastasis in sentinel lymph nodes: Clinical outcome in 94 dogs with mast cell tumor

BACKGROUND

The therapeutic role and prognostic relevance of lymphadenectomy in mast cell tumor (MCT) has historically been evaluated on regional rather than sentinel lymph nodes.

HYPOTHESIS/OBJECTIVES

To update information about the association of histological nodal (HN) classes with clinical outcome in dogs with MCT after tumor excision and extirpation of normal-sized sentinel nodes (SLN) guided by radiopharmaceutical.

ANIMALS

Ninety-four dogs with histologically-confirmed treatment-naïve MCT (71 cutaneous, 22 subcutaneous and 1 conjunctival MCT) were included if without: distant metastases, lymphadenomegaly, concurrent mixed cutaneous, and subcutaneous MCT.

METHODS

This was a monoistitutional cohort study. Tumors characteristics were retrieved and SLNs were classified according to Weishaar's system. Incidence of MCT-related events (local, nodal, distant relapse), de novo MCT or other tumors and death (MCT-related and non-MCT-related), were recorded. Incidence curves were compared among the HN classes.

RESULTS

Twenty-seven dogs had HN0, 19 HN1, 37 HN2, and 11 HN3 SLN. Thirteen (2 HN0, 4 HN2, and 7 HN3) received adjuvant chemotherapies. Kiupel high grade, increasing number of SLN and lymphocentrums were associated with higher HN classes. Five dogs died for MCT-related causes: 1 low-grade (HN0) and 1 subcutaneous (HN3) had a local relapse, 2 high-grade had distant relapse (HN3-HN0) and 1 dog developed disease progression from a de novo subcutaneous MCT. No nodal relapse was registered. Fourteen dogs developed de novo MCTs.

CONCLUSION/DISCUSSION

Low grade/low-risk MCT with nonpalpable and normal sized SLN have a favorable outcome independently from the HN. Result should be considered strictly related to the successful SLN detection guided pre- and intraoperative by radiopharmaceutical markers.

Basal cell adenocarcinoma on bulbar conjunctiva of third eyelid in a dog

An 8-year-old castrated Toy poodle presented with swelling and proptosis of the right third eyelid caused by an exophytic mass on the bulbar surface. Histologically, the mass was composed of stratified neoplastic basaloid cells, arranged in nests and interconnecting islands, which were mixed with tubular structures. Immunohistochemically, the basaloid cells were positive for p63 and cytokeratin (CK) 14, and the inner epithelial cells of the tubular structures were positive for CK7, CK8, and CK19. According to these findings, the mass was diagnosed as a basal cell adenocarcinoma. Although basal cell adenocarcinoma is rare in animals, it should be included in the list of differential diagnoses for superficial tumors of bulbar conjunctiva of third eyelid in dogs.

Angioceratoma conjuntival canino: relato de caso

RESUMO O angioceratoma é um tumor de origem vascular, semelhante ao hemangioma, que se diferencia deste por alterações histológicas epiteliais. A apresentação ocular do angioceratoma é pouco frequente em cães, sendo mais comum a ocorrência de hemangioma e hemangiossarcoma. Neste relato, é descrito o caso de um cão, macho, da raça Border Collie, que apresentava uma massa localizada, hiperêmica, bem vascularizada e protrusa, na região temporal da conjuntiva bulbar do olho direito (OD). Foi realizado exame oftalmológico completo e ultrassonografia ocular, tendo sido possível observar que a massa não envolvia outras estruturas oculares além da conjuntiva. Dessa forma, foi realizada a conjuntivectomia parcial, e o material foi encaminhado para análise histológica. O exame histopatológico foi conclusivo para um angioceratoma e mostrou que as margens da amostra estavam livres. O procedimento cirúrgico com margem de segurança foi eficiente no tratamento da neoplasia, sem recorrência até o momento do presente relato.

Feline Epitheliotropic Mastocytic Conjunctivitis in 15 Cats

Mast cell infiltration occurs in malignant, inflammatory (eg, allergic, infectious), and idiopathic disease processes in humans and animals. Here, we describe the clinical and histological features of a unique proliferative conjunctivitis occurring in 15 cats. Ocular specimens were examined histologically, and polymerase chain reaction (PCR) for feline herpesvirus 1 (FHV-1) was performed on ocular tissues obtained from 10 cats. Cats had a median age of 8 years (range: 7 months-17.5 years). The known median duration of ocular lesions prior to biopsy was 4 months (range: 1 week-3 years). Ocular disease was unilateral in 12 cats, and 9 cats had coexisting corneal disease. Clinically and histologically, proliferative or nodular conjunctival lesions were noted in 13 cats. The nictitating membrane was affected in 10 cats. Histologically, lesions were characterized by mixed inflammatory infiltrates with an abundance of Giemsa-positive and toluidine blue-positive intraepithelial and subepithelial mast cells, marked edema, and papillary epithelial hyperplasia. Feline herpesvirus 1 was demonstrated by PCR in 1 of 10 cats tested. Follow-up information was available for 14 cats: 8 had no recurrence during a median follow-up period of 17.5 months (range: 4.5-30 months), 2 underwent orbital exenteration, 3 had recurrence that was medically managed, and 1 cat had diffuse conjunctivitis at the time of biopsy and recurrence was deemed irrelevant. Various ocular medications were administered before and after surgical biopsy. This condition was designated as feline epitheliotropic mastocytic conjunctivitis, with intraepithelial mast cells being an essential feature and papillary epithelial proliferation being characteristic but not diagnostic alone. The condition appears to be uncommon and benign. Although the cause is unknown, an allergic component is possible.

Biology and Diseases of Dogs

Historically, the dog played an important role as a laboratory animal in biomedical research. Although numbers are declining, the use of dogs continues to be common in pharmacokinetics and cardiovascular studies. The normal biology of the dog as both a laboratory and a companion animal has been well studied and reference values are presented here as a clinical and experimental resource. This provides the necessary background to discuss the spontaneous diseases, including infectious and neoplastic conditions, prevalent in purpose bred as well as random source dogs used in biomedical research. In addition, diseases and conditions that arise secondary to the housing and experimental manipulation of dogs is discussed with emphasis on treatment and prevention.

Canine mast cell tumors: diagnosis, treatment, and prognosis

Mast cell tumors (MCTs) are the most common malignant skin cancer in dogs, and significant variability exists in their biological behavior. Most MCTs are cured with appropriate local therapy, but a subset shows malignant behavior with the potential to spread to lymph nodes, liver, spleen, and other areas and to thus become a systemic cancer. Because of this variable behavior, it is difficult to predict how any individual tumor is going to behave. The variability thus creates uncertainty in deciding what a particular dog’s prognosis is, whether staging tests to assess for metastasis are needed, and even what treatments will be necessary for best outcome. In addition to controversies over the potential for development of systemic disease, or diffuse metastasis, controversies also exist over what treatment is needed to best attain local control of these tumors. This article will briefly discuss the diagnosis of MCTs in dogs and will summarize the literature in regards to the controversial topics surrounding the more aggressive form of this disease, with recommendations made based on published studies.

Unilateral intraocular mastocytosis and anterior uveitis in a dog with subcutaneous mast cell tumors

A 9-year-old male castrated Scottish terrier was referred to the Radiation Oncology Service at the William R. Pritchard Veterinary Medical Teaching Hospital for palliative radiation therapy of an incompletely excised, recurrent subcutaneous mast cell tumor (MCT) located over the right scapula, and surgical removal of a perianal MCT. Three weeks after initial presentation and prior to the fifth radiation treatment, the patient was presented with cloudiness of the left eye of 3-7 days duration. Ophthalmic consultation revealed 3+ aqueous flare with a dependent, swirling component filling approximately one-third of the anterior chamber. Aqueocentesis was performed under general anesthesia. Cytology revealed mast cells with highly atypical morphology and considered most consistent with neoplasia. The patient died 7 months after pathologic diagnosis of MCT on the right shoulder and 2 months after the cytologic diagnosis of malignant mast cells in the left anterior chamber. To the authors' knowledge, this is the first report of intraocular involvement in a mammal with MCTs, described here as intraocular mastocytosis.