OBJECTIVE: The objective of our study was to assess the characteristics of locoregional lymph node enlargement after successful radiofrequency ablation (RFA) in the treatment of malignant lung tumors. MATERIALS AND METHODS: Follow-up CT examinations of 14 patients (seven men, seven women; age range, 30-90 years) who underwent 16 RFA sessions for the treatment of primary (n = 9) or metastatic (n = 5) lung tumors with a mean follow-up of 35 +/- 15 (SD) months (range, 7-60 months) were retrospectively reviewed by two thoracic radiologists. The site and size of hilar and mediastinal lymph nodes were recorded at baseline and at follow-up 1, 3, and 6 months after RFA sessions. In addition, the size, type, and location of the ablated lesion or lesions were recorded. All complications from RFA were recorded. Data were analyzed using the Fisher's exact test. RESULTS: An increase in lymph node size was detected after 10 of 16 (62.5%) RFA sessions at 1-month follow-up. In four of 10 patients, only one node had enlarged, and in the remaining six patients, more than one nodal region had enlarged. The average increase in nodal size was 3 mm in the short-axis diameter and 4 mm in the long-axis diameter. Twenty-eight percent of RFA sessions were associated with enlargement of at least one lymph node to greater than 10 mm in short-axis diameter at 1-month follow-up. CT showed that nodes had decreased in size at 3- and 6-month follow-ups. Lesion size, location, and complications were not shown to be significantly associated with mediastinal lymph node enlargement (p > 0.05). CONCLUSION: Recognition of reversible locoregional lymph node enlargement after RFA is important to prevent misdiagnosis of nodal metastatic disease.
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