Swelling of the cervical lymph nodes may indicate lymphadenitis, malignant lymphoma, or metastasis. Lymph nodes larger than 10 mm on computed tomography (CT) are strongly indicative of postoperative metastasis from carcinoma. Here, we report a case of large, inflamed lymph nodes mimicking metastasis. The patient was a 76-year-old woman who experienced discomfort in the left-side maxillary gingiva commencing in August 2011. By September, the area had become painful, causing her to visit the Tokyo Dental College Chiba Hospital, at which time a 75×50-mm swollen ulcer was observed in the maxillary gingiva on the left side. A CT image revealed a neoplastic lesion between the alveolar bone on the left side of the maxilla and the base of the maxillary sinus, together with evidence of osteoclastic activity. The bilateral cervical lymph nodes were Level II and had a uniform interior of approximately 5 mm. The lesion was subsequently excised under general anesthesia. At 34 days postoperatively, CT imaging revealed bilateral 40-mm internal heterogeneous lymphadenopathy at Level II. No inflammation of the maxillary gingiva was observed, however, and blood tests revealed no inflammatory findings. Bilateral cervical lymph node metastasis was diagnosed based on CT and oral cavity observation. Radical neck dissection of left cervical region was performed under general anesthesia. Histopathological examination of the lymph nodes revealed no metastasis at Levels I–V, however. The reason for this increase in lymph node size is discussed.