IMAGE OF THE MONTH An Unusual Cause of Lower Gastrointestinal Bleeding Rahman Nakshabendi,* Andrew C. Berry,* and Juan C. Munoz‡ *Department of Medicine, ‡Department of Medicine, Division of Gastroenterology, University of Florida College of Medicine-Jacksonville, Jacksonville, Florida
53-year-old Caucasian woman presented with complaints of abdominal pain, constipation, pyrosis, and occasional red blood in her stool for 6 months’ duration. The abdominal pain was burning in nature, worse with eating, and radiated from her chest to her back. Physical examination was unremarkable and did not show any pigmentation of the skin or the eyes. Hemoglobin and hematocrit levels on admission were 14.3 g/dL and 43.1%, respectively. Colonoscopy showed internal hemorrhoids and a bi-lobed rectal polyp measuring 1.5 cm, which was snared and retrieved (Figures A and B). Immunohistochemical analysis was strongly positive for S-100, melan A, HMB-45, and negative for chromogranin, which is most consistent with the diagnosis of malignant melanoma (Figure C). After the skin and retina, anorectal malignant melanoma is the third most common location of melanoma. Anorectal melanomas make up less than 3% of all melanomas, and less than 1% of all malignant tumors of the anorectum are melanoma.1 Malignant melanomas can occur in the anorectum because of the presence of abundant melanocytes in the mucosa of the anal canal. However, only 20% of patients have clear melanin pigmentation.2 It is because of this that many of the symptoms, such as bleeding, often are confused with symptoms from hemorrhoids. The majority of patients who have malignant melanoma do not have clinically apparent gastrointestinal involvement antemortem. Melanomas with gastrointestinal involvement most commonly arise from metastasis from a known site. Commonly, metastatic melanoma patients manifest with
A
prior cutaneous and/or ocular involvement. However, metastasis from an unknown primary also can arise. In these situations, it is important to see whether the patient had any prior excised lesions, metastasis, or tumor regression. The patient in the case described had a solitary lesion combined with no prior cutaneous or ocular involvement and no prior excised lesions, metastasis, or tumor regression. Colonoscopy performed 1 year previously showed only internal hemorrhoids present in the anorectal area. These characteristics combined with immunohistochemical analysis positive for S-100, melan A, and HMB-45 represent a rare case of primary malignant melanoma of the rectum. Symptoms of hematochezia, especially when accompanied with systemic symptoms, may indicate serious underlying pathology. In this case, the patient was found to have an anorectal melanoma 1 year after an unrevealing colonoscopy.
References 1.
Schuchter LM, Green R, Fraker D. Primary and metastatic diseases in malignant melanoma of the gastrointestinal tract. Curr Opin Oncol 2000;12:181–185.
2.
Tpomioka T, Ojima H, Sohda M, et al. Primary malignant melanoma of the rectum: report of two cases. Case Rep Surg 2012; 2012:247348.
Conflicts of interest The authors disclose no conflicts. © 2015 by the AGA Institute 1542-3565/$36.00 http://dx.doi.org/10.1016/j.cgh.2014.11.016
Clinical Gastroenterology and Hepatology 2015;13:xxiii
53-year-old Caucasian woman presented with complaints of abdominal pain, constipation, pyrosis, and occasional red blood in her stool for 6 months’ duration. The abdominal pain was burning in nature, worse with eating, and radiated from her chest to her back. Physical examination was unremarkable and did not show any pigmentation of the skin or the eyes. Hemoglobin and hematocrit levels on admission were 14.3 g/dL and 43.1%, respectively. Colonoscopy showed internal hemorrhoids and a bi-lobed rectal polyp measuring 1.5 cm, which was snared and retrieved (Figures A and B). Immunohistochemical analysis was strongly positive for S-100, melan A, HMB-45, and negative for chromogranin, which is most consistent with the diagnosis of malignant melanoma (Figure C). After the skin and retina, anorectal malignant melanoma is the third most common location of melanoma. Anorectal melanomas make up less than 3% of all melanomas, and less than 1% of all malignant tumors of the anorectum are melanoma.1 Malignant melanomas can occur in the anorectum because of the presence of abundant melanocytes in the mucosa of the anal canal. However, only 20% of patients have clear melanin pigmentation.2 It is because of this that many of the symptoms, such as bleeding, often are confused with symptoms from hemorrhoids. The majority of patients who have malignant melanoma do not have clinically apparent gastrointestinal involvement antemortem. Melanomas with gastrointestinal involvement most commonly arise from metastasis from a known site. Commonly, metastatic melanoma patients manifest with
A
prior cutaneous and/or ocular involvement. However, metastasis from an unknown primary also can arise. In these situations, it is important to see whether the patient had any prior excised lesions, metastasis, or tumor regression. The patient in the case described had a solitary lesion combined with no prior cutaneous or ocular involvement and no prior excised lesions, metastasis, or tumor regression. Colonoscopy performed 1 year previously showed only internal hemorrhoids present in the anorectal area. These characteristics combined with immunohistochemical analysis positive for S-100, melan A, and HMB-45 represent a rare case of primary malignant melanoma of the rectum. Symptoms of hematochezia, especially when accompanied with systemic symptoms, may indicate serious underlying pathology. In this case, the patient was found to have an anorectal melanoma 1 year after an unrevealing colonoscopy.
References 1.
Schuchter LM, Green R, Fraker D. Primary and metastatic diseases in malignant melanoma of the gastrointestinal tract. Curr Opin Oncol 2000;12:181–185.
2.
Tpomioka T, Ojima H, Sohda M, et al. Primary malignant melanoma of the rectum: report of two cases. Case Rep Surg 2012; 2012:247348.
Conflicts of interest The authors disclose no conflicts. © 2015 by the AGA Institute 1542-3565/$36.00 http://dx.doi.org/10.1016/j.cgh.2014.11.016
Clinical Gastroenterology and Hepatology 2015;13:xxiii
