Pathogenesis, diagnosis and management of primary melanoma of the colon

Abstract

BackgroundMelanomas within the alimentary tract are usually metastatic in origin. On the other hand, primary melanomas of the gastrointestinal tract are relatively uncommon. There are several published reports of melanomas occurring in the esophagus, stomach, small bowel, and anorectum. The occurrence of primary melanoma of the colon has, however, only been rarely reported. The optimum modus operandi for the management of primary colonic melanoma remains nebulous due to the limited number of reports in literature.MethodsA comprehensive search of Medline, Cochrane and Highwire was performed using the following keywords: 'melanoma', 'malignant melanoma', 'primary melanoma', 'colon', 'gastrointestinal tract', 'alimentary tract', 'digestive tract', and 'large bowel'. All patients with primary melanoma localized to the colon were included in the review. Patients with metastatic melanomas to the gastrointestinal (GI) tract and primary melanomas localized to the GI tract in anatomic locations other than colon were excluded.ResultsThere have been only 12 reported cases of primary melanoma of the colon to date. The average age of patients on presentation was 60.4 years without any significant gender predilection. Right colon (33%) and cecum (33%) were the most common sites for the occurrence of primary colonic melanoma while abdominal pain (58%) and weight loss (50%) were the most common presenting complaints. Colonoscopy is the most reliable diagnostic investigation and offers the additional advantage of obtaining tissue for diagnosis. S-100 and HMB-45 are highly sensitive and specific for the diagnosis of this malignancy. For primary colonic melanomas that have not metastasized to any distant parts of the body, surgical resection with wide margins appears to be the treatment of choice. Although the management was individualized in every case, most of the authors preferred traditional hemicolectomy as the favored surgical approach. Chemotherapeutic agents including interferons, cytokines, biological agents and radiation therapy for brain metastases have been reported as adjuvant and palliative options while considering malignant melanomas in general. The average recurrence-free interval was 2.59 years. Nine of the 12 reports documented follow-up in their patients. Two of these 9 (22.2%) patients died.ConclusionsPrimary melanoma of the colon is a rare clinical entity. Whenever a seemingly primary melanoma is detected in an atypical location such as the colon, it is prudent to conduct a thorough clinical investigation to consider the possibility of metastatic disease. Further studies are needed to document the long term follow-up, survival advantage and safety of the management approaches employed in patients with primary colonic melanoma. Based on current data, surgical resection appears to be appropriate management for primary colonic melanomas; unless the disease has metastasized to distant sites where surgery may have a limited palliative role.

Ileocecal Intussusception Secondary to Bowel Metastases from Cutaneous Melanoma: Case Report

“…It is a known fact generally, that achieving negative surgical margins is the main principle of oncologic surgery and in patients, who have localized disease curative resection with wide margins is the crucial method. 16 On the other hand, if the patient has widespread disease or has multipl affected sites in the GIT, palliative surgery should be considered to relieve the symptoms of intestinal obstruction. 17 There are no effective chemotherapy regimens for prolong the survival of metastatic melanoma, but some agents may control the disseminated disease, reduce the local recurrence and improve the quality of life.…”

Primary Melanoma of the Right Colon Presenting With Gastrointestinal Bleeding

“…[12] In the only series of patients who had surgery for primary melanoma in various sites of the colon, the average time to recurrence was 2.59 years. [11] Presentation with obstruction or perforation was associated with a worse prognosis.…”

“…The occurrence of primary melanoma of the colon is relatively rare, with 12 cases reported in the literature to date, [11] with the right colon and the caecum being the commonest sites. This contrasts with metastatic melanoma, which seems to preferentially involve the ascending and descending colon [12].…”

“…Aggressive surgical intervention with wide excision margins is the first line treatment for localised resectable disease [11]. The role of adjuvant or neoadjuvant therapy in the setting of primary melanoma is also debatable as melanoma is generally chemoresistant.…”

Primary digestive melanoma in association with tubular adenoma: a case report illustrating the distinction from metastatic colonic melanoma

“…Other digestive localizations are exceedingly rare and affect the right colon and cecum, whereas ascending, transverse and descending colon are considered as the most frequent sites for metastatic colonic melanoma [3]. MM occurring at the anal site display acrolentiginous features, while histopathological features at the colonic level have not been well defined [2].…”