Appendicitis secondary to metastatic melanoma: review of the National Institutes of Health experience.

Importance: Malignant melanoma has an unusual propensity to metastasize to the small bowel; however, malignant melanoma with metastatic spread to the appendix presenting as acute appendicitis has rarely been reported. We describe cases of melanoma of the appendix presenting with appendicitis and review our institutional experience with this entity.
Observations: Medical records were reviewed in patients with melanoma at the National Cancer Institute between January 1, 1953, and December 31, 2010, who underwent appendectomy. Of 5822 cases of melanoma treated at the National Institutes of Health, appendectomies were performed on 31 patients, 2 of whom had acute appendicitis secondary to malignant obstruction and presented with symptoms of vague abdominal pain. Both patients had been heavily pretreated for metastatic melanoma and had multiple sites of intraperitoneal and extraperitoneal disease. On exploratory laparotomy, both patients showed clinical evidence of acute appendicitis, and an appendectomy was performed. Both patients recovered fully from the operation and proceeded to further systemic therapy.
Conclusions and Relevance: Although rare, the diagnosis of appendicitis should be considered in patients with melanoma and acute abdominal pain. Timely surgical intervention may allow palliation and the ability to pursue subsequent systemic treatment.