An 8-year-old boy suffered from worsening snoring and obstructive sleep apnea that had begun 4 months prior. The patient developed a fever and persistent yellowish nasal discharge, leading to a diagnosis of acute otitis media at a local clinic. Fever and nasal symptoms did not improve, irrespective of 6 weeks of antibiotic treatment. Moreover, the patient was developing hearing impairment. Neck computed tomography was performed, revealing a nasopharyngeal mass and hypertrophy of both palatine tonsils. A punch biopsy of the nasopharyngeal mass confirmed a diagnosis of malignant B-cell lymphoma. The patient was subsequently transferred to our hospital for further evaluation and treatment. On hospital day 6, the patient experienced anal itching, and two parasite segments were detected in his stool. Two years prior, the patient visited Jeju-do, consumed seafood dishes, and thereafter experienced four or five episodes of the emergence of this parasite. The patient and all his family members received early albendazole treatment; however, the symptoms recurred intermittently. Nonetheless, the patient presented no abdominal symptoms, such as nausea, vomiting, abdominal pain, diarrhea, or constipation. The patient had a self-reported history of raw beef and fish consumption and no history of traveling abroad. Laboratory findings revealed a mild degree of eosinophilia (eosinophil count: 791/μL). Two segments that had passed out in his stool were submitted to our clinical laboratory. The segments exhibited movement, and they were pressed between two microscope slides and examined macroscopically without staining. More than 15 branched uterine structures were observed in the segments. However, Taenia species ova were not identified upon stool examination using the formalin–ether concentration method. T. saginata-induced taeniasis was tentatively diagnosed based on the proglottid morphology. After praziquantel (10 mg/kg) treatment, long parasite segments approximately 84 cm in length were expelled (Fig. 1A). To identify the tapeworm species, we conducted a molecular analysis of the proglottid segments. Genomic DNA was extracted using the QIAamp DNA Mini Kit (Qiagen, Hilden, Germany) and subsequently used as a template for polymerase chain reaction (PCR) analysis. The mitochondrial cytochrome c oxidase subunit I (cox1) gene was targeted for PCR amplification. The PCR primers were as follows: Tsag cox 1 F (5′- GAG GAA ATT GTG AAG TTA CTG CTA-3′) and Tsag cox 1 R (5′- ATG ATG CAA AAG GCA AAT AAA CCT-3′). PCR was performed using a 30-μL reaction mixture containing 15 μL Smart 2 × PCR Pre-Mix (SolGent Co., Ltd., Daejeon, Korea), 2 μL template DNA, 10 μM of each primer, and 11 μL distilled water, as described in a previous study [4,6]. The amplification process comprised pre-denaturation (94°C for 3 min), 40 cycles of denaturation (94°C for 60 s), annealing (52°C for 60 s), extension (72°C for 60 s), and final extension (72°C for 10 min). The PCR products were sent to Cosmogenetech (Seoul, Korea) for direct sequencing using the same PCR primers. The 1750-bp cox1 sequence had a 100%, 95.9%, and 92.7% match with the T. saginata (accession no. AB465235), T. asiatica (accession no. AP017670), and T. multiceps (accession no. JX535570) sequences, respectively. DNA sequences were aligned using the CLUSTAL W computer program [7]. Phylogenetic trees were constructed using the neighbor-joining method, and genetic distances were computed via the Tamura–Nei method using the Geneious computer program [8]. The neighbor-joining tree based on GenBank sequences indicated that our specimen was in the same phylogenetic group as T. saginata, but not in the same group as T. asiatica, T. multiceps, or T. solium (Fig. 1B). No T. saginata proglottids or ova were detected in his stool, and the patient subsequently commenced chemotherapy for ly phoma.