Malignant Duodenal Melanoma Presenting as Iron Deficiency Anemia

Abstract

Purpose: Malignant duodenal melanomas may be primary or metastatic lesions which can precede the onset of seemingly benign gastrointestinal symptoms including iron deficiency anemia by an average of > 4 years. Methods: A 48-year-old male presenting after an opiate and benzodiazepine overdose was found to be anemic with a hemoglobin of 6.4 mg/dl and an MCV of 72.3 fl. He reported generalized malaise and weight loss of 26 pounds over the past 2 months. He was transfused with two units of packed red blood cells and underwent endoscopic evaluation which found a mass in the third portion of the duodenum. Unfortunately, the patient left the hospital against medical advice prior to determining a histologic diagnosis of the findings found on esophagogastroduodenoscopy and numerous attempts to contact the patient afterwards were futile. Results: Esophagogastroduodenoscopy found a large fungating ulcerated mass in the third portion of the duodenum which histology later demonstrated as a malignant melanoma. Conclusion: Malignant melanomas can originate in as well as metastasize to the gastrointestinal tract. Primary malignant duodenal neoplasms are relatively rare and the diagnosis is often delayed because of their vague and nonspecific symptoms which may include weight loss, symptomatic anemia or an upper or lower gastrointestinal bleed. The criteria for the diagnosis of primary melanomas include lack of concurrent or previous removal of a melanoma or atypical melanocytic lesion from the skin, lack of other organ involvement, and in situ change in the overlying or adjacent gastrointestinal epithelium. Malignant melanomas, however, are the most common source of metastatic cancers to the gastrointestinal tract. Between 1% and 4% of all patients with malignant melanomas will have clinically apparent GI involvement diagnosed ante mortem and up to 60% are found to have gastrointestinal metastases at autopsy. Early detection of gastrointestinal metastases using abdominal CT scan has been shown to be useful in asymptomatic patients or those with nonspecific symptoms. Aggressive surgery remains the treatment of choice offering both symptom palliation and long-term survival for patients, with the median survival after curative resection in the small intestine being 49 months and the longest reported survival being 21 years. This case is presented to increase the awareness of considering malignant melanomas in the differential of iron deficiency anemia and the importance of investigating primary skin and ocular lesions since early detection and management can improve patient outcome.