RESUMEN
Nodal metastatic foci of colorectal carcinoma are usually solid nodules. Serous inclusions are occasionally found in lymph nodes, particularly in female patients, and they occasionally form cysts. An 86-year-old woman was treated with laparoscopic low anterior resection and D3 lymph node dissection for advanced rectal carcinoma. A cyst with serous fluid and no necrotic debris was found within one of the dissected pararectal lymph nodes. Histologically, the cyst was lined by low columnar-to-cuboid epithelium with mild nuclear atypia, mimicking a serous inclusion cyst. Immunohistochemically, the epithelial cells were positive for caudal type homeobox 2 and negative for Wilms' tumor suppressor gene1. Immunohistochemistry for p53 showed a diffuse strong positivity, indicating a mutant TP53 as seen in primary rectal carcinoma. Thus, the nodal cystic lesion was confirmed to be a metastatic lesion. It is important to carefully assess a nodal cystic lesion to confirm whether it is benign or malignant.