Primary malignant melanoma of the small intestine: report of a case

An Intestinal Melanoma of Unknown Origin Presenting as an Intussusception: A Case Report of a Rare Entity

Melanoma involving the gastrointestinal (GI) tract is an exceedingly rare and clinically challenging entity, often presenting with nonspecific symptoms that can delay diagnosis and treatment. This report describes the case of a 74-year-old male with a history of melanoma of unknown primary origin who presented with acute intestinal obstruction secondary to metastatic melanoma in the small intestine. The patient's clinical course was complicated by intermittent subocclusion, anemia, and hemodynamic instability, culminating in exploratory laparotomy and resection of the affected intestinal segment. Histopathological examination confirmed metastatic melanoma, positive for SOX10, HMB45, and Ki67 markers. This case highlights the diagnostic and therapeutic challenges of GI melanoma, emphasizing the importance of considering rare malignancies in patients with atypical abdominal symptoms, particularly those with a history of melanoma. The discussion underscores the aggressive nature of GI melanoma, the role of surgery as the primary treatment modality, and the need for further research into systemic therapies to improve outcomes in this patient population.

Clinical and pathological characteristics of pulmonary meningioma: a case report and literature review

This case report aimed to examine the clinical pathological characteristics, immunohistochemical phenotype, and differential diagnosis of primary pulmonary meningioma (PM), which is a rare tumor. A retrospective analysis was conducted on the clinical data, imaging manifestations, histological features, immunohistochemical results, and in situ hybridization results of a 60-year-old male patient who underwent surgical resection and was diagnosed with PM by pathology. Additionally, the relevant literature was reviewed. Multiple nodules were detected in the right lung of the patient during a re-examination because of a novel coronavirus infection but there were no obvious clinical symptoms. Imaging revealed well-defined masses in the upper, middle, and lower lobes of the right lung, and the masses were surgically removed. Microscopy showed that the boundary between the tumor and surrounding lung tissue was clear, and consisted of spindle cells and epithelioid cells. The final diagnosis was multiple grade II meningiomas of the right lung. No postoperative radiotherapy or chemotherapy was performed. There was no recurrence or metastasis during a 6-month follow-up. Pulmonary metastatic meningioma is rare, while primary PM is even rarer. Surgical resection is the preferred treatment method for PM, with a generally good prognosis, but a few malignant manifestations may require close follow-up.

Primary malignant melanoma of the small bowel: A case report

Malignant melanoma comprises 1%-3% of all malignant tumors of the gastrointestinal tract. The small bowel melanoma is an extremely rare malignancy. Very few cases have been reported in the literature. The small intestine is mostly affected by the metastatic tumors of the primary lesions especially cutaneous. This malignancy is diagnosed at the late stages as the patient remains asymptomatic. In this report we present a case of malignant melanoma arising from the small bowel in a 58-year-old male. There was no primary lesion in the eye, skin, anus, rectum or elsewhere in the body. The patient was treated with surgery. Afterward the patient presented to the emergency room with respiratory distress for which he was on ventilator support, sadly the patient died after 10 days. Malignant melanoma is an aggressive tumor and does not respond well to chemotherapy or radiotherapy.

Primary Duodenal Melanoma: Challenges in Diagnosis and Management of a Rare Entity

Primary melanoma of the duodenum is an extremely rare, aggressive and life-threatening malignant neoplasm. Published data regarding the effectiveness of current treatment strategies is limited, and our knowledge relies mostly on sporadic case reports. The diagnosis of primary duodenal melanoma is challenging and is based on the patient's medical history and findings from physical examination and radiological and endoscopic imaging as well as proper and careful pathological examinations of the tumor. Despite the many advances in cancer treatment, the prognosis for patients with this type of melanoma remains extremely poor. Delayed diagnosis at advanced disease stage, the general aggressive behavior of this neoplasm, the technical difficulty in achieving complete surgical resection, along with the rich vascular and lymphatic drainage of the intestinal mucosa, all have a negative impact on patients' outcome. In the present review, we aimed to collect and summarize the currently available data in the literature regarding the pathogenesis, clinical features, diagnosis, management and long-term outcomes of this rare, malignant tumor, in order to expand knowledge of its biological behavior and investigate optimal therapeutic options for these patients. Additionally, we present our experience of a case involving a 73-year-old female with primary duodenal melanoma, who was successfully treated with complete surgical resection.

Primary jejunal amelanotic melanoma: case report and review of literature

Intussusception more commonly occurs in pediatrics but is a rare cause of bowel obstruction and gastrointestinal bleeding in adults. It typically occurs in adults due to a malignancy, which serves as a pathologic lead point. We present a case of a 64-year-old female with nausea, vomiting, and melena who was found to have intussusception associated with a primary jejunal amelanotic melanoma. Both intussusception and primary small bowel melanomas are rare causes of obstruction and bleeding. Intussusception occurring as a result of a primary small bowel amelanotic melanoma is exceedingly rare with very few reported cases. We provide a case report and review of the literature.

Presentation, Management, and Prognosis of Primary Gastrointestinal Melanoma: A Population-Based Study

BACKGROUND

Primary gastrointestinal (GI) melanomas, compared with cutaneous melanomas, have a much lower incidence. As a result, there is a paucity of data regarding their presentation, treatment, and prognosis. The aim of this study was to analyze the incidence, patient characteristics, treatment patterns, and survival of primary GI melanomas in comparison with cutaneous melanomas using a population-based cohort.

METHODS

Patients diagnosed with primary GI and cutaneous melanomas were identified from Surveillance, Epidemiology, and End Results 1973-2016 data.

RESULTS

A total of 872 primary GI melanomas and 319,327 cutaneous melanomas were identified. GI melanoma incidence increased by an annual percent change of 1.82 (P < 0.05) during the study period. The most common sites for GI melanoma were the anus (50%) and rectum (34%). Compared to cutaneous melanoma, patients diagnosed with GI melanomas were older, women (58% versus 45%), non-White (16% versus 6%), and presented with a higher stage (36% versus 4% distant stage, all P < 0.001). GI melanomas had significantly worse cancer-specific survival (CSS) than cutaneous melanoma. Despite the poor prognosis, the CSS has increased in recent years. Among patients with anorectal melanomas, local excision with chemotherapy and/or radiation had a similar CSS compared with those with major surgery only.

CONCLUSIONS

Despite a steady increasing incidence since 1975, GI melanomas are rare, present with advanced stages, and have worse outcomes than cutaneous melanomas. The improved prognosis of these tumors in recent years might reflect the impact of novel targeted treatments and the more common use of local tumor excision over major resections.

Ileal Melanoma, A Rare Cause of Small Bowel Obstruction: Report of a Case, and Short Literature Review

BACKGROUND

Malignant melanoma frequently spreads to the gastrointestinal tract, with 60% of patients with advanced metastatic disease showing digestive involvement; however, primary MM of the small intestine is a controversial diagnosis. In fact, whether these lesions arise as true small bowel primary neoplasms or represent metastases from unidentified cutaneous melanomas remains debatable. The most common complications are intestinal obstruction, massive gastrointestinal bleeding, and perforation.

OBJECTIVE & METHODS

We report a case of a 64-year-old patient, with an unremarkable medical history, in which a late diagnosis of primary ileal malignant melanoma in the setting of an emergency laparotomy due to small bowel obstruction, and where PET-scan showed costal metastasis. Therefore, we provide a narrative review of the scientific literature about this topic.

RESULTS

36 cases of primary small bowel melanoma, included that in the present study, were found through our search in the scientific literature.

CONCLUSION

Primary small bowel MM appears to be an extremely rare entity which clinicians should be more aware of, in order to plan better a correct strategy of early diagnosis and appropriate treatment.

Primary Malignant Melanoma of the Small Bowel a Case Report and Review of the Literature

Although small bowel involvement by malignant melanoma is most frequently metastatic, a primary origin at this site has been reported in rare cases. The biological and clinical features of these cases have not yet been summarized. Here, another case of small bowel melanoma is described, and a review of the existing literature is given. An 81-year-old man presented with anemia and gastrointestinal bleeding. A tumor of the ileum was detected by video capsule endoscopy and removed by segment resection. Histological examination revealed a malignant melanoma of the ileum. Another primary site could be excluded by clinical and radiographic examination. The patient felt well five months after surgery.

Only 18 cases of primary small bowel melanoma (including the present one) have been reported to date. A literature review reveals that this rare neoplasm is associated with a slight predilection for the male gender, a predilection for the ileum and a poor prognosis.

Primary jejunal melanoma as a cause of adult intussusception: a case report and review of literature

Primary melanoma of the small bowel is a rare clinical entity with a paucity of published reports in literature. Most cases of gastrointestinal melanomas are metastatic lesions arising from skin or ocular origins. This is a case report of a 63 year old female with adult intussusception with jejunal melanoma as the lead point. The index patient had a long history of abdominal pain associated with significant weight loss and presented with features of intestinal obstruction. The possibility of a regressed or unidentified extra-intestinal site cannot be absolutely excluded as the patient did not have a PET scan. Due to the vague nature of clinical symptoms and signs, the diagnosis of small bowel melanoma is difficult, especially in patients with no obvious cutaneous pathology. A high index of suspicion for melanoma as a malignant lead point for adult intussusception should always be entertained.

A Case of Primary Small Bowel Melanoma Diagnosed by Single-Balloon Enteroscopy

Although metastasis from cutaneous malignant melanoma to the small intestine is not uncommon, primary small bowel melanoma (SBM) is extremely rare. This case report describes a rare case of primary SBM, diagnosed by single-balloon enteroscopy. A 74-year-old man presented with recurrent melena. Upper endoscopy and colonoscopy were unremarkable. Abdominal computed tomography (CT) revealed an ileal mass with ileo-ileal intussusception. Subsequent single-balloon enteroscopy identified an ileal tumor, which was histologically diagnosed as melanoma. Extensive clinical examination did not reveal any primary cutaneous lesions. To the best of our knowledge, this is the first case of primary SBM in South Korea.

Primary melanoma of the small bowel revealed by gastrointestinal bleeding: a case report

Background

Primary melanoma of the small bowel is extremely rare. Only a limited number of cases have been described in the literature. Mostly, the small intestine is affected by metastatic tumors of other primary lesions, especially cutaneous.

Case presentation

We report the case of a 75-year-old North African woman with a small bowel melanoma. The diagnosis was made by histological examination and immunohistochemical profile matching after a segmental small bowel resection. Postoperative investigations looking for cutaneous, gastrointestinal or ocular primary lesions found no abnormalities.

Conclusions

The diagnosis of primary small bowel melanoma can be retained although it remains difficult to exclude the possibility of metastatic melanoma.

Primary small bowel melanomas: fact or myth?

Small bowel melanoma (SBM) is a rare entity, which often evades diagnosis and therefore presents late. Its origin, whether arising primarily or metastatically from an unidentified or regressed primary cutaneous melanoma, remains debatable. In this report, we present a rare case of primary SBM and review the current literature. A 60-year-old man presented with melena and microcytic anemia. A series of investigations including abdominal ultrasonography (US), esophago-gastro-duodenoscopy (EGD) and colonoscopy were normal. Abdominal computed tomography revealed no specific pathology. Subsequent capsule endoscopy identified a jejunal mass, which was confirmed on laparotomy, was resected, and histologically diagnosed as melanoma. Extensive postoperative clinical examination revealed no cutaneous lesions. This report discusses gastrointestinal (GI) malignant melanoma, and examines the evidence both for and against the existence of true primary vs. metastatic disease. Furthermore, this case highlights the capabilities of capsule endoscopy in identifying an extremely rare GI tumor, which evaded other diagnostic modalities. Finally, the origins and pathophysiology of this rare cancer are evaluated, with the aim of promoting early diagnosis and treatment, and therefore improving current poor outcomes.

Duodenal and gallbladder metastasis of regressive melanoma: a case report and review of the literature

BACKGROUND

Malignant melanoma involving the gastrointestinal (GI) tract may be primary or metastatic. Small bowel is the commonest site of GI metastases from cutaneous malignant melanoma, metastatic lesion in the gallbladder is extremely rare.

CASE PRESENTATION

This case report describes the presentation of metastatic melanoma in duodenum and gallbladder. A 45-year-old man has presented melena with intermittent abdominal pain. On physical examination we found a small lesion between the fourth and fifth toes, associated with inguinal lymph node. An Abdominal ultrasound revealed diffuse duodenal thickening. Upper endoscopy was performed and discovered an ulcerative lesion in the second part of the duodenum. The biopsy with immunohistochemical stains was in favor of a duodenal location of melanoma. Computed tomography (CT) revealed many circumferential thickening of ileal loops associated with a nodular lesion in the anterior wall of the gallbladder. The patient was treated by palliative chemotherapy.

DISCUSSION

Malignant melanoma of the GI tract may be primary or secondary. The small bowel is the most affected, but it's rare in the gallbladder. The clinical presentation can mimic the other intestinal tumors, and the diagnosis is based on imaging; CT scan and GI endoscopy have a key role on the diagnosis, and the treatment depends on the location and the number of lesions.

CONCLUSIONS

Metastases of melanoma in the GI tract are uncommon, the diagnosis must be suspected in any patient with a history of melanoma with digestive signs.

Primary colonic melanoma presenting as ileocecal intussusception: Case report and literature review

Primary malignant melanoma originating in the colon is an extremely rare disease. Herein, we report a case of primary melanoma of the ascending colon. The patient was a 57-year-old male who was admitted to our hospital for persistent abdominal pain and episodes of bloody stool, nausea and vomiting. A computed tomography scan revealed lower intestinal intussusception and enlarged lymph nodes in the abdominal cavity and retroperitoneum. During laparoscopic operation, multiple enlarged lymph nodes were found. Several segments of the proximal small intestine were incarcerated into the distal small intestine, forming an internal hernia and obstruction. The necrotic terminal ileum was invaginated into the ascending cecum. Subsequently, adhesive internal hernia reduction and palliative right hemicolectomy were performed. Pathologic examination of the excised specimen revealed a polypoid mass in the ascending colon. Histological examination showed epithelioid and spindle tumor cells with obvious cytoplasmic melanin deposition. Immunohistochemical staining revealed that the tumor cells were positive for S-100, HMB-45 and vimentin, confirming the diagnosis of melanoma. The patient history and a thorough postoperative investigation excluded the preexistence or coexistence of a primary lesion elsewhere in the skin, anus or oculus or at other sites. Thus, we consider our case to represent an aggressive primary colon melanoma presenting as ileocecal intussusception and intestinal obstruction.

Intestinal obstruction due to primary intestinal melanoma in a patient with a history of rectal cancer resectioning: A case report

The vast majority of the cases of intestinal melanomas are metastatic lesions, originating from an occult primary cutaneous or ocular lesion, whereas primary small intestinal melanomas are extremely rare. This is a rare case of primary small intestinal malignant melanoma with intestinal obstruction in a patient with a prior history of rectal cancer resection. The patient was admitted for abdominal pain and obstipation. Following an overall inspection, the patient was subjected to surgical treatment and a small intestinal tumor was removed. The histopathological examination of the lesion revealed a diffuse neoplastic infiltration involving the entire thickness of the intestinal mucosa. The neoplastic cells exhibited marked atypia, pleomorphism and immunoreactivity to S-100, anti-melanoma antibody (HMB-45) and melanocyte/melanoma tumor antigen (Melan-A). The diagnosis of primary small intestinal melanoma was confirmed. The patient underwent an uneventful postoperative recovery and was administered adjuvant therapy. At the 3-month, 6-month and 1-year follow-up, the patient remained alive, with no signs of tumor metastasis and/or recurrence. In this case, the patient was repetitively assessed by abdominal computed tomography (CT) and plain film, confirming that the obstruction was caused by small intestinal melanoma. There was no association between the rectal cancer history and the melanoma. A definitive diagnosis requires detailed clinical, histopathological and immunohistochemical analyses.

Survival after resection of a primary malignant melanoma of the small intestine in a young patient: report of a case

The occurrence of primary melanoma of the small intestine is rare. We describe the case of a 25-year-old man found to have a primary melanoma of the ileum. The patient presented with gradual onset of abdominal pain, fever, diarrhea, weight loss and fatigue. A preoperative diagnosis of a small intestinal tumor was based on the findings of computed tomography scanning. This diagnosis was confirmed at laparoto-my and a partial small bowel resection was performed. Histopathological examination of the resected specimen clarified the exact nature of the lesion, confirming the diagnosis of melanoma. Thorough postoperative investigation did not reveal a primary lesion in the skin, gastrointestinal tract, oculus or brain. Thus, we diagnosed this tumor as a primary lesion. One year after his operation, the patient remains well without any evidence of recurrence. Thus, we diagnosed this small bowel tumor as a primary melanoma of the small intestine.

Primary malignant melanoma of the duodenum without visible melanin pigment: a mimicker of lymphoma or carcinoma

Primary malignant melanoma of the duodenum is an unusual oncologic entity. Patients usually present the similar clinical symptoms like other common tumors in this site. And there are no specific radiological features either. The cases with only little melanin pigment or without notable melanin pigment are very misleading, especially in small biopsies or frozen sections. Definite diagnosis depends on both careful histologic examination and the use of proper immunohistochemical stains. Moreover, detailed history and thorough investigation should be made to exclude the preexistence or coexistence of a primary lesion elsewhere. Herein we report the case of a 60-year-old male patient with primary malignant melanoma of the duodenum, which was misdiagnosed as lymphoma or undifferentiated carcinoma in frozen consultation. The patient had achieved disease-free survival for more than 46 months without any evidence of recurrence after surgery.

Epithelioid melanoma of the rectum: reappraisal of a deceptive microscopic simulator

We report 2 cases of rectal melanoma. The patients were a 48-year-old man and an 88-year-old woman. In both cases, the tumor presented as polypoid and necrotic masses, making initial diagnostic assessment difficult because of the regressive tissue changes. Microscopically, tumors were mostly composed of epithelioid, highly atypical cells mimicking poorly differentiated carcinoma or large cell lymphoma. Tumor cells were negative for keratin, leukocyte common antigen, and epithelial membrane antigen and positive for S100 protein and several melanoma markers, although in endoscopic biopsy specimens, the positive reaction was focal due to the limited viable tissue. One patient was treated with abdominoperineal resection. Pathologic examination of the surgical specimen revealed a polypoid mass infiltrating the muscle coat of the rectum. Local lymph nodes contained metastatic deposits. Microscopic examination of the rectal mucosa adjacent to the infiltrating neoplasm revealed colonization of the intestinal crypts by atypical melanocytes. This patient is alive 1 year after surgery with no evidence of recurrent disease. The other case was not deemed amenable to radical surgery because of the patient's advanced age and evidence of diffuse metastatic disease. She was alive 6 months after the initial diagnosis but was lost to follow-up. Data indicate that the diagnosis of melanoma, although feasible in large resection specimens, may be problematic in endoscopic biopsy, especially when only small tissue fragments are available and tumor regression hampers the accuracy of immunohistochemical stains. Documentation of intracryptic atypical melanocytes in nonneoplastic mucosa conceptually corroborates claims that rectal melanoma is related to preinvasive precursors as in cutaneous melanoma.

Melanoma of the small intestine

Intestinal melanomas can be primary tumours or metastases of cutaneous, ocular, or anal melanomas. Primary intestinal melanoma is extremely rare, whereas metastatic melanoma of the small bowel is common because of the tendency for cutaneous melanoma to metastasise to the gastrointestinal tract. Because distinguishing between primary and metastatic intestinal melanoma can be difficult, the main features of each are discussed, and the diagnostic images used to detect intestinal melanoma are assessed. Routine barium examinations and CT have limited sensitivity, but PET imaging can improve detection of melanoma metastases to the small bowel. Although various treatment strategies have been tried in patients with intestinal melanoma, surgical removal of intestinal metastases is the treatment of choice in patients with resectable tumours. No systemic therapy improves survival in patients with melanoma metastatic to the intestines; thus, the prognosis for these patients is poor. Patients with primary melanoma of the small intestine have a worse prognosis than do patients with metastases of cutaneous melanoma.

Primary malignant melanoma of the duodenum: aggressive management and long-term survival of an unusual oncologic entity

Primary malignant melanoma originating in the small bowel is extremely rare. We report the case of a 55-year-old man who presented with a preoperative bleeding duodenal tumor. A standard pancreaticoduodenectomy was performed. Histopathological examination ascertained the diagnosis of a duodenal malignant melanoma with locoregional lymphatic spread. A thorough postoperative investigation did not reveal any primary melanotic lesions. Thus, the diagnosis of a primary melanoma originating from the duodenum was suggested. Fourteen months after surgery, the patient had no evidence of recurrence. Primary malignant melanoma of the duodenum is an existing, though unusual, oncologic entity. Aggressive surgery remains the treatment of choice offering both symptom palliation and long-term survival.

Defining the role of surgery for primary gastrointestinal tract melanoma

OBJECTIVE

The objective of the study was to determine the outcomes for primary gastrointestinal melanomas (PGIM).

MATERIAL AND METHODS

The Surveillance, Epidemiology, and End Results database (1973-2004) was queried.

RESULTS

Overall, 659 cases of PGIM were identified. The annual incidence of PGIM was approximately 0.47 cases per million in 2000. Overall median survival time was 17 months. Tumors were identified in the oral-nasopharynx (32.8%), anal canal (31.4%), rectum (22.2%), esophagus (5.9%), stomach (2.7%), small bowel (2.3%), gallbladder (1.4%), and large bowel (0.9%). Univariate analysis demonstrated age, tumor location, stage, surgery, and lymph node status were significant predictors of improved survival. MST has not been reached for tumors located in the large bowel, while tumors located in the stomach demonstrated the shortest median survival (5 months). Improvement in MST was observed for those patients undergoing surgical resection. The presence of lymph node involvement conferred a poorer prognosis. Multivariate analysis of the cohort identified that location, advanced tumor stage, failure to undertake surgical resection, positive lymph node status, and age were all independent predictors of poorer outcome.

CONCLUSION

PGIM occurs most often in the oral-nasopharynx and anal canal. Surgical extirpation is the only identifiable treatment modality that significantly improves survival.

Gastrointestinal stromal tumors: diagnostic challenges and practical approach to differential diagnosis

Over the last decade, gastrointestinal stromal tumors (GISTs) have evolved from histogenetically obscure gastrointestinal mesenchymal tumors to well-defined tumors with distinctive clinical, morphologic, ultrastructural, histogenetic, and molecular characteristics, for which targeted therapy is available. This is largely attributable to the discovery of CD117 overexpression and activating mutations in c-kit or platelet-derived growth factor alpha genes in most of GISTs. The availability of specific diagnostic tests and targeted therapy for GISTs has led to an increased awareness of these tumors. At the same time, the list of potential GIST mimics has lengthened considerably and it has become increasingly important that GISTs be distinguished from their mimics because correct diagnosis has implications for both treatment and prognosis. The purpose of this review is to provide an update of the expanding differential diagnosis of GISTS, to draw attention to unusual GIST variants, to provide a practical approach the differential diagnosis of GISTs and to highlight some of the challenges faced by pathologists in resolving this differential diagnosis.

Ileal malignant melanoma causing intussusception: report of a case

Cutaneous malignant melanoma (MM) often metastasizes to the gastrointestinal (GI) tract; however, primary MM of the small intestine is a controversial diagnosis. We report the case of a 76-year-old woman found to have a primary MM in the ileum. After clinical evaluation, the radiological workup, which included magnetic resonance enteroclysis (MRE), revealed a large polypoid intraluminal tumor. She underwent laparotomy and the lesion was excised. Histological examination of the resected specimen revealed morphological and immunohistochemical characteristics of MM and a detailed postoperative examination failed to identify a primary lesion on the skin, anus, oculus, or any other site. The patient died of brain metastasis 6 months after surgery. According to our review of the literature, this is the first case of primary MM of the small intestine diagnosed with the help of MRE.

Primary colonic malignant melanoma

Primary malignant melanoma originating in the digestive tract is extremely rare. A case of primary malignant melanoma in the descending colon is described. The tumor was an elevated mass with surface necrosis. Histologically, tumor cells were arranged with compact nests surrounded by fibrous stroma. The tumor cells had pleomorphic nuclei and rich cytoplasm. In some areas, cells of signet ring-like appearance were found. An immunohistochemical examination showed that most of the tumor cells were positive for S-100 protein, HMB-45, melan-A, vimentin and CD38. Ultrastructural examination confirmed some premelanosomes. EWS-ATF-1 fusion transcript, which is usually detected in clear cell sarcoma, was not demonstrated on reverse transcriptase-polymerase chain reaction. Because there was no evidence of either cutaneous or ocular primary melanoma, the tumor was thus diagnosed as primary colonic malignant melanoma. The patient has remained free of recurrent disease for 3 years after a surgical resection. Colonic malignant melanoma must be differentiated from other intestinal tumor, and the possibility of metastasis from another more common primary site must be ruled out.

Primary Malignant Melanoma of the Right Colon

The small and large intestines are the most common sites for metastases from cutaneous malignant melanoma. However, primary melanomas in these sites are exceedingly rare. There are several case reports of patients with primary melanoma of the small bowel, but finding of a solitary primary melanoma in the colon is exceedingly rare. We describe a patient that was operated on for bowel obstruction due to colonic intussusception resulting from a right colonic tumor. Histopathological examination confirmed a diagnosis of malignant melanoma. A thorough postoperative investigation did not reveal a primary lesion in any other site. Two years after surgery, there was no evidence for recurrent disease. The treatment and prognosis of metastatic and primary melanoma of the gastrointestinal tract is discussed as well as the embryonic base for development of primary malignant melanoma of the intestine. Primary malignant melanoma of the intestine is an extremely rare lesion that may arise in the large bowel as well. It must be differentiated from other intestinal tumors and mandates a thorough investigation to rule out the possibility of being a metastasis from another more common primary site.