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Year : 2019  |  Volume : 62  |  Issue : 4  |  Page : 641-642
Primary melanoma of cecum: A diagnostic challenge

1 Department of Laboratory Medicine, Aseer Central Hospital, Abha, KSA, Saudi Arabia
2 Department of Pathology, King Khalid University, Abha, KSA, Saudi Arabia

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Date of Web Publication14-Oct-2019

How to cite this article:
Alwani NM, Fatima S, Adiga BK, Haider N. Primary melanoma of cecum: A diagnostic challenge. Indian J Pathol Microbiol 2019;62:641-2

How to cite this URL:
Alwani NM, Fatima S, Adiga BK, Haider N. Primary melanoma of cecum: A diagnostic challenge. Indian J Pathol Microbiol [serial online] 2019 [cited 2023 Jan 27];62:641-2. Available from:


Melanomas are aggressive malignant tumors arising from melanocytes, which are neural crest-derived cells located in the basal layer of skin, hair follicles, squamous-covered mucosal membranes, and leptomeninges.[1] They are mainly found in the head and neck area and lower extremities. They account for <3% of all gastrointestinal tract (GIT) malignancies and are mainly metastatic in origin.[2] GIT is rarely the site of primary melanoma; however, metastasis to liver, small intestine, colon, and stomach occurs in decreasing order of incidence. About 60% of those with melanoma have GIT metastases at the time of autopsy.[3] We report a case of 47-year-old female who presented with intussusception and was diagnosed as primary cecal melanoma.

A 47-year-old female presented with right-sided abdominal pain and discomfort, nausea, and weight loss. The computed tomography (CT) of the abdomen with contrast revealed findings of irregular cecal wall thickening, ileocecal intussusception with matted bowel loops, and heterogeneous mass measuring 12 × 5 cm in right iliac fossa with subcentimeter lymphadenopathy. Terminal ileum showed wall thickening with mild dilatation of its distal part. The transverse colon and descending colon were collapsed. Subsequently, the patient underwent right hemicolectomy with resection of terminal ileum, cecum, appendix, ascending colon, part of transverse colon, and part of mesentery. Gross examination of the resected specimen showed a perforation in cecum measuring 2 × 2 cm. Cut section revealed a polypoid tumor mass in cecum measuring 10 × 8 × 4 cm invading the whole wall of colon and pericolic fat [Figure 1]a and [Figure 1]b. The mesentery included 17 lymph nodes, largest measuring 1.5 × 1 cm. Histologically, the mass was composed of sheets and nests of malignant cells. The tumor cells showed large pleomorphic hyperchromatic nuclei with prominent nucleoli and granular to clear cytoplasm. Several atypical mitoses and necrotic areas were seen [Figure 1]c and [Figure 1]d. The tumor extended through muscularis propria into serosa and pericolic fat (pT3), one of 17 lymph nodes was involved by tumor (N1). Immunohistochemical stain for HMB-45 was positive [Figure 2]a with focal positivity for melan-A and S100 [Figure 2]b and [Figure 2]c. The tumor was mitotically active with 60% Ki67 positivity. The tumor cells were negative for pan-cytokeratin, CD34, CD117, desmin, myogenin, smooth muscle actin, CD45, CDX2, CEA, HCG, CD30, AFP, and chromogranin. There was no history of cutaneous melanoma and physical and ophthalmological examination was normal. These findings were consistent with primary cecal amelanotic melanoma.
Figure 1: (a) Gross examination of the resection specimen showing a perforation in cecum measuring 2 × 2 cm. (b). Cut section revealing a polypoid tumor mass in cecum measuring 10 × 8 × 4 cm invading the whole wall of colon and pericolic fat. (c) Section showing cecal mucosa and tumor in submucosa (hematoxylin and eosin 10×). (d) Tumor composed of malignant cells in alveolar pattern. The tumor cells show large pleomorphic hyperchromatic nuclei with prominent nucleoli (hematoxylin and eosin 20×)

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Figure 2: An immunohistochemical study. (a) Showing human melanoma black-45 positivity in malignant cells (HMB 45 20×). (b) Showing Melan A positivity in malignant cells (Melan A 20×). (c) S100 positivity in malignant cells (S100 20×)

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Extracutaneous melanomas include ocular, mucosal, leptomeningeal, and rare cases originating in some internal organs. Primary mucosal melanomas arise from melanocytes located in mucosal membranes lining respiratory, gastrointestinal, and urogenital tract.[3] These arise at any site of gastrointestinal mucosa, most common being anorectum (31.4% in the anal canal and 22.2% in the rectum) and oropharynx (32.8%), whereas esophagus (5.9%), stomach (2.7%), small bowel (2.3%), gallbladder (1.4%), and large bowel (0.9%) are extremely rare sites of origin.[4] Blecker et al. proposed the following criteria for diagnosis of primary melanoma of bowel: presence of a solitary mucosal lesion in the intestinal epithelium, absence of melanoma or atypical melanocytic lesions of the skin, and presence of intramucosal melanocytic lesions in the overlying or adjacent intestinal epithelium.[5] However, a clear distinction between primary intestinal melanoma and metastatic deposits can be difficult when considering histopathological features alone.

Primary melanoma of the colon is exceptionally rare tumor with 14 cases reported to date. Mean age of patients on presentation is 60.4 years, with no gender predilection.[3] Tumors are mainly located in the right colon and cecum;[6] however, transverse colon involvement has also been seen.[7] The most common presentations being abdominal pain and weight loss.[6]

Neural crest–derived cells which are abundant within the bowel are considered to arise from the caudal branchial arches during embryogenesis. Cells with melanogenic potential are unable to colonize the bowel perhaps because of factors produced within the branchial arches [8] explaining the rarity of large bowel melanoma. Ectodermic cells capable of differentiating into multiple cell lines, including those of melanocytic derivation may approach the distal ileum and right colon via the omphalomesenteric duct and give rise to melanoma.[6] GI melanomas manifest from melanoma at another site, and if not found are called melanoma of unknown primary.[8]

The diagnosis is usually established by Barium studies, colonoscopy, which is the gold standard and CT scan. In our case, CT scan was done as patient presented with abdominal pain and intussusception. Malignant melanoma is notorious for exhibiting great microscopic variability. Melanin can be abundant, scanty, or absent (amelanotic melanoma).[1] Cells are generally positive for S-100 protein, NSE, Melan A, PAX3, HMB45, and vimentin; the intensity of these reactions shows marked variability depending on the functional status of the cells. Our case was amelanotic with the differential diagnosis including undifferentiated carcinoma, melanoma, gastrointestinal stromal tumor, clear cell sarcoma of soft parts (CCSS), epithelioid malignant peripheral nerve sheath tumor, and perivascular epithelioid cell tumor. CCSS exhibits t (12;22)(q13;q12), EWS/ATF1 gene region rearrangement.

Mucosal melanomas show overexpression of KIT in 39% of cases [9] providing a hope that KIT inhibitors such as imatinib and sunitinib could be effective therapeutic agents.[3] Aggressive surgical resection has been the mainstay of treatment for most melanomas that have not disseminated at the time of diagnosis followed by postoperative radiation therapy, chemotherapy, and immunotherapy for any residual disease or nodal involvement.[4] The prognosis of primary malignant melanoma of the colon appears to be better than other types of primary mucosal melanomas. However, both tend to be more aggressive than their cutaneous counterparts. In conclusion, primary melanoma of colon is a rare aggressive tumor, which needs to be differentiated from metastatic tumor with surgical resection being the main modality of treatment.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.

   References Top

Billings SD. Tumors and Tumorlike Conditions of the Skin. Rosai and Ackerman's Surgical Pathology. 11th ed., Vol. 2. St. Louis, Missouri: Mosby; 2017.  Back to cited text no. 1
Castro-Villabón D, Mojica I, López R, Esquinas P, García A, Rodríguez-Urrego PA. Melanoma involving the ileum: Report of a case and review of literature. Case Rep Clin Med 2014;3:42-6.  Back to cited text no. 2
Mihajlovic M, Vlajkovic S, Jovanovic P, Stefanovic V. Primary mucosal melanomas: A comprehensive review. Int J Clin Exp Pathol 2012;5:739-53.  Back to cited text no. 3
Cheung MC, Perez EA, Molina MA, Jin X, Gutierrez JC, Franceschi D, et al. Defining the role of surgery for primary gastrointestinal tract melanoma. J Gastrointest Surg 2008;12:731-8.  Back to cited text no. 4
Blecker D, Abraham S, Furth EE, Kochman ML. Melanoma in the gastrointestinal tract. Am J Gastroenterol 1999;94:3427-33.  Back to cited text no. 5
Khalid U, Saleem T, Imam AM, Khan MR. Pathogenesis, diagnosis and management of primary melanoma of the colon. World J Surg Oncol 2011;9:14.  Back to cited text no. 6
Raja J, Hegde R, Srodon M, Katoch A, Kurtzman S, Zhang Z. A Case of primary melanoma of the transverse colon. Cureus 2017;9:e1803.  Back to cited text no. 7
Jacobs-Cohen RJ, Wade PR, Gershon MD. Suppression of the melanogenic potential of migrating neural crest–derived cells by the branchial arches. Anat Rec 2002;268:16-26.  Back to cited text no. 8
Curtin JA, Busam K, Pinkel D, Bastian BC. Somatic activation of KIT in distinct subtypes of melanoma. J Clin Oncol 2006;24:4340-6.  Back to cited text no. 9

Correspondence Address:
Sohaila Fatima
King Khalid University, Abha
Saudi Arabia
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/IJPM.IJPM_636_18

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