Mucinous adenocarcinoma of the appendix is a rare neoplasm with a low propensity for lymph node metastasis. The present case refers to an appendicular mucinous adenocarcinoma with inguinal lymph node metastasis. A 71-year-old woman underwent an appendectomy due to a clinical presentation of acute appendicitis. However, the histological examination of the surgical specimen revealed a mucinous adenocarcinoma of the appendix. After staging, the patient underwent a right hemicolectomy and was proposed for adjuvant chemotherapy. At the 3rd year of follow-up, inguinal lymphadenopathy was diagnosed, which biopsy confirmed inguinal node metastases from primary colorectal cancer, with areas of extracellular mucin. Restaging revealed liver and peritoneal metastasis, and the patient was proposed for palliative chemotherapy. Appendicular neoplasms, due to their rarity, represent a diagnostic and therapeutic challenge. This clinical case depicts an unusual metastasis pathway for an unusual neoplasm.