Pacientes com carcinoma de células escamosas - relação do tratamento com o prognóstico

Abstract

Background: Squamous cell carcinoma (SCC) is a malignant cutaneous neoplasm which occurs frequently in small animals. Histopathology or fine needle aspiration cytology is necessary to confirm diagnosis; macroscopic diagnosis is not possible since the lesions are very similar to others of distinct etiologies. Owing to the fact that it is a neoplasm, diagnosis and treatment are usually not well accepted by owners, especially since it can cause esthetic changes to the animal and adjunct treatments can cause unwanted side effects. The objective of this study was to report clinical cases of SCC with distinct tumor subtypes and relate the recommended treatment with prognosis of patients.

Case: Two dogs and one cat with SCC that were subjected to physical and dermatological examination, and tested negative for sporotrichosis, cryptococcosis, and manges. Dog 1 (male, 9-year-old, yellow Labrador retriever) exhibited inspiratory dyspnea for three weeks owing to an ulcerative hemorrhagic lesion on the nose. In view of the site of the lesion, a radiographic exam was requested, and the bony portion of the septum was found to be compromised. Cat 2 (female, 10-year-old, bicolor, mixed-breed cat) exhibited a focal, punctate, ulcerated, hemorrhagic lesion on the nose. Dog 3 (female, 10-year-old, white Dogo Argentino) exhibited several ulcerative lesions, and papulae, plaques and comedones on the ventral region of the abdomen.Treatment for deep pyoderma and comedone syndrome were initially instituted; on follow-up, more ulcerative lesions were present, which prompted the inclusion of neoplasm as a differential diagnosis. In cases 1 and 3, histopathology was performed with diagnosis of undifferentiated and differentiated SCC, respectively. In both cases, surgical margins were compromised after resection of the lesion. In case 2, high malignancy SCC was diagnosed with cytology. Use of sunscreen was recommended in all cases, as well as avoidance of sun exposure during the hours not recommended by the National Cancer Institute. In case 1, a nosectomy with partial resection of the nasal septum was recommended as well as chemotherapy with intra-tumoral administration of carboplatin (1.5 mg/cm3 of lesion) and vincristine sulfate (0.05 mg/ kg/IV/week) every 15 days.However, the owner opted for the nosectomy alone with one month of chemotherapy with vincristine sulfate. In case 2, polychemotherapy was instituted using daunorubicin (4 mg/kg/IV/week) and vincristine sulfate (0.05 mg/kg/IV/week) every 15 days for four weeks, with maintenance for six weeks, with total remission of the lesion at the end of treatment. In case 3, eight intralesional chemotherapy sessions were performed (carboplatin – 1.5 mg/cm3 of lesion) every 15 days; maintenance was kept for two months with biweekly administration. The patient exhibited actinic lesions on the third month after the protocol was suspended, which was treated with isotretinoin (3 mg/kg/day PO) until remission; reduction of solar exposure was recommended. The animal in case 1 exhibited intense dyspnea three months after the end of treatment and the lesion was incompatible with preservation of quality of life and euthanasia was performed. In the other two cases, patients were followed-up annually and remained in remission throughout life.

Discussion: Adherence to proposed treatment by the owner is directly related to a better prognosis. On the punctate and focal lesion in the cat, administrations of daunorubicin (4 mg/kg/IV/week) and vincristine sulfate (0.05 mg/kg/IV/week) in a total of 10 cycles resulted in an excellent prognosis. On the dog with multifocal lesions, partial resection and intralesional administration of carboplatin (1.5 mg/lesion/cm3) in a total of eight biweekly applications following maintenance for two months resulted in a good prognosis.