RESUMEN
BACKGROUND: Pneumatosis intestinalis is a rare disease characterized by gas-filled cysts within the submucosa or serosa of the intestinal tract. In recent years, pneumatosis intestinalis was reported in patients undergoing cancer treatment, and some case reports exist that report that pneumatosis intestinalis occurs during administration of vascular endothelial growth factor inhibitors, such as bevacizumab and sunitinib. Here, we report the first case of pneumatosis intestinalis during lenvatinib treatment. CASE PRESENTATION: A 77-year-old Japanese man presented to our hospital with a chief complaint of numbness in the right leg and weakness of the lower limbs 9 years after right thyroid lobectomy. Computed tomography showed a tumor 90 mm in size from the lumbar spine to the sacrum, causing spinal cord compression. Blood tests showed that the patient's thyroglobulin level was increased to 11,600 ng/ml. We diagnosed him with thyroid cancer with bone metastases. External beam radiotherapy (39 Gy/13 Fr) was performed on the bone metastases, followed by total thyroidectomy and radioactive iodine therapy. Four months after radioactive iodine therapy, lenvatinib was introduced because the symptoms of numbness and weakness recurred. Lenvatinib was introduced at dose of 24 mg, and then it was reduced to 14 mg owing to Common Terminology Criteria for Adverse Event grade 3 paronychia of the right foot. Although no further significant adverse events occurred, a scheduled computed tomography image showed pneumatosis intestinalis of the ascending colon 14 weeks after the introduction of lenvatinib. No abdominal or digestive symptoms were observed; therefore, we selected conservative treatment. We discontinued lenvatinib for a week, but we were required to restart lenvatinib as the numbness in the right leg worsened after withdrawal. Since the introduction of lenvatinib, 3 years and 5 months passed; we continued lenvatinib treatment, and the therapeutic effect remains partial response. There has been no recurrence of pneumatosis intestinalis. CONCLUSIONS: Although rare, it is important to recognize that pneumatosis intestinalis can occur in association with lenvatinib and should be differentiated from intestinal perforation. Pneumatosis intestinalis association with lenvatinib can be improved by withdrawal.