PURPOSE: To report a case of tonsillar asymmetry presenting as the primary sign of a diffuse large B cell lymphoma. CASE REPORT: A 41-year-old white woman housekeeper was evaluated in December 2012 for swelling of the right tonsil associated with dysphagia and odynophagia. She was a non-smoker and denied alcohol consumption. She was seen at a local otorhinolaryngology (ORL) service and was treated with antibiotics and an anti-inflammatory for 14 days; however, her condition continued to deteriorate with worsening dysphagia and phonation disorder. The patient sought treatment at the ORL division of Sao Jose do Avai Hospital. Fiberoscopy showed tonsillar asymmetry with enlargement of the right tonsil. The tonsillar mucosa was hardened and fixed, and the uvula was shifted to the left. The left tonsil was clinically changed. There were no palpable cervical lymph nodes. The patient was referred for surgery, and on January 20, 2013, a right tonsillectomy was performed without complications. Subsequent pathological examination and immunohistochemical analysis confirmed the diagnosis of a diffuse large B cell lymphoma in the right tonsil. The patient's speech improved immediately after the surgery. She was referred to the oncology service and was undergoing chemotherapy at the time of this report. CONCLUSION: Waldeyer's ring is one of the extra nodal sites commonly involved in diffuse large B cell lymphoma, with the tonsils being most commonly affected site. Malignancy should be considered when a patient presents with tonsillar asymmetry and tonsillectomy should be performed whenever there is such a suspicion.