OBJECTIVES: Describe a rare case of dacryocystomucopyocele caused by the surgical approach taken to the paranasal sinuses. CASE REPORT: E.P.S., 61-year-old brown man started to complain of redness, tearing, pain, swelling in the left eye, cacosmia, and bloody/purulent oral discharge 9 months ago. There were no other complaints. At follow-up, there was an increase in intraocular pressure due to the presence of a lesion expanding toward the orbit. As a child, the patient had undergone sinus surgery (Caldwell Luc). The physical examination revealed bulging of the orbital floor. Anterior rhinoscopy revealed no active discharge in the middle meatus. The oral exam showed a fistula with purulent discharge on the left canine. Tomography of the orbits revealed an expansive lesion infiltrating the left nasolacrimal duct, extending to the masticatory space and infratemporal and temporal fossae, with slight marginal enhancement of the lesion, corresponding to mucocele. Intravenous antibiotic therapy was administered and endoscopy was performed (uncinectomy and maxillary antrostomy). We observed abundant purulent discharge from the maxillary sinus and a thick-walled cystic lesion in the region of the nasolacrimal sac. The cyst was removed from the left nasal cavity by using the "Caldwell Luc" technique. Pathological analysis allowed for the identification of respiratory mucosa with hyperplasia of the seromucosa acini, fibrosis, and chronic nonspecific inflammation. CONCLUSION: Dacryocystocele should be considered in the differential diagnosis of patients with obstruction of the lacrimal sac or duct in association with an expansive lesion.