Indian Journal of Pathology and Microbiology

LETTERS TO EDITOR
Year
: 2019  |  Volume : 62  |  Issue : 4  |  Page : 641--642

Primary melanoma of cecum: A diagnostic challenge


Nouha Mahmood Alwani1, Sohaila Fatima2, Balkur Krishnamoorthi Adiga2, Nazima Haider2,  
1 Department of Laboratory Medicine, Aseer Central Hospital, Abha, KSA, Saudi Arabia
2 Department of Pathology, King Khalid University, Abha, KSA, Saudi Arabia

Correspondence Address:
Sohaila Fatima
King Khalid University, Abha
Saudi Arabia




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;62:641-642


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 2021 Jun 23 ];62:641-642
Available from: https://www.ijpmonline.org/text.asp?2019/62/4/641/269077


Full Text



Editor,

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 [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}{Figure 2}

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.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

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