RESUMO
Background: Sinus neoplasms are reported as low frequency in horses. Its clinical characteristics are often nonspecific, depend on complementary methods for diagnosis, and when diagnosed, generally they are already advanced, limiting therapeutic possibilities. The objective of this case series was to detail clinical aspects and complementary exams for sinus neoplasms for early diagnosis, comparing them with the literature. Cases: Four horses were treated at the College of Veterinary Medicine and Animal Science of the University of São Paulo, with different clinical signs and previous diagnoses, which when evaluated by respiratory endoscopy, radiography, oral cavity evaluation and histopathological exams, revealed the diagnosis of anaplastic carcinoma, poorly differentiated carcinoma, ossifying fibroma and lymphoma. Previous diagnosis, based mainly on clinical signs, were sinusitis secondary to apical infection, ethmoidal hematoma, sinus cyst and sinusitis secondary to periapical disease. The cases of anaplastic carcinoma (case 1) and lymphoma (case 4) presented with an advanced degree of the disease with involvement and destruction of paranasal structures and adjacent tissues, in addition to a poor general condition, which made surgical treatment impossible and led to euthanasia. In these cases, previous treatment was made to apical infection and periodontal disease with secondary sinusitis, but negative evolution led to suspicion of neoplasia, confirmed by histopathological exam of incisional biopsy of the mass in oral cavity. Benign ossifying fibroma (case 3) presented with progressive respiratory difficulty due to occlusion of the lumen of some nasal meatus and radiographic signs of invasion and deformation of the adjacent bones, it was submitted for surgical excision and there was no recurrence until hospital discharge. The poorly differentiated carcinoma (case 2) was a multilobulate neoformation in the ethmoidal region, similar to ethmoid hematoma in endoscopic and radiographic evaluation, it was submitted for excision and two sessions of electrochemotherapy with bleomycin, associated with administration of piroxicam, which obtained a good result until the period of 1 year after discharge. Discussion: It was found that many characteristics are common with these types of neoplasms, and the clinical signs, such as nasal secretions, airway obstruction, increased facial volume, severe alterations in oral cavity, although unspecific, suggest the differential diagnosis for neoplasms. It is important to differentiate from other diseases noting the evolution and growth of these tumors, like in cases 1 and 4, especially the growth to internal tissues, using complementary methods described here, like endoscopic and radiographic examination. Late identification or even manipulation of neoplasms, without proper diagnosis, leads to a few prognoses regarding life. When it is possible to perform surgical excision, complementary methods are important to guide the procedure, and definitive diagnosis is made through histopathologic exam and some need immunohistochemistry analysis. Cases 2 and 3 had surgical access, were submitted to excision and treatment with good results, both with close monitoring in first months and prolonged quality of life. These results highlight the importance of complementary methods for early diagnosis, correct intervention and monitoring of evolution.