Distant metastasis from papillary thyroid carcinoma (PTC), particularly from papillary thyroid microcarcinoma, is rare. We present a case of perigastric lymph node metastasis from PTC in a patient with early gastric cancer and breast cancer. During post-surgical follow-up for breast cancer, a 56-year-old woman was diagnosed incidentally with early gastric cancer and synchronous left thyroid cancer. Therefore, laparoscopic distal gastrectomy with lymph node dissection and left thyroidectomy were performed. On the basis of the pathologic findings of the surgical specimens, the patient was diagnosed to have papillary thyroid microcarcinoma with perigastric lymph node metastasis and early gastric cancer with mucosal invasion. Finally, on the basis of immunohistochemical staining with galectin-3, the diagnosis of perigastric lymph node metastasis from PTC was made. When a patient has multiple primary malignancies with lymph node metastasis, careful pathologic examination of the surgical specimen is necessary; immunohistochemical staining may be helpful in determining the primary origin of lymph node metastasis.