Biomarkers and Genomic Medicine (2013) 5, 113e116

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CASE REPORT

Ileus secondary to a retroperitonealmalignant melanoma

Chin-Fan Chen a,b, Chieh-Han Chuang c, Ching Hu d,Jaw-Yuan Wang a,b,e,*

aDepartment of Surgery, Kaohsiung Medical University Hospital, Kaohsiung, TaiwanbGraduate Institute of Clinical Medicine, College of Medicine, Kaohsiung Medical University,Kaohsiung, TaiwancDepartment of Surgery, Kaohsiung Municipal Hsiao-Kang Hospital, Kaohsiung, TaiwandDepartment of Pathology, Pingtung Hospital, Department of Health, Executive Yuan,Pingtung, Taiwane Faculty of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan

Received 23 June 2013; received in revised form 31 July 2013; accepted 31 July 2013Available online 8 September 2013

KEYWORDSileus;malignant melanoma;retroperitoneum

* Corresponding author. DepartmentKaohsiung 807, Taiwan.

E-mail address: cy614112@ms14.h

2214-0247/$36 Copyright ª 2013, Taiwhttp://dx.doi.org/10.1016/j.bgm.201

Abstract Retroperitoneal malignant melanomas, either primary or metastatic, are rare. Wepresent our clinical experience concerning one case with ileus secondary to a huge retroper-itoneal malignant melanoma. A 77-year-old woman was admitted to the hospital due to pro-gressive abdominal fullness and decreased appetite for 4 months. Plain films showed soft-tissue density in the left lower quadrant of the abdomen, as well as rightward displacementof the intestine. Laboratory data excluded any metabolic or septic causes of ileus. Abdominalcomputed tomography scan identified a huge retroperitoneal tumor with invasion of the leftlower peritoneal space. The mass measured approximately 18.2 � 21.5 cm in the largest sec-tion. Immunohistochemical analysis of the tumor biopsies at minilaparotomy showed positivestaining of tumor cells for S-100 protein, human melanoma black-45, and vimentin. Thus, adiagnosis of malignant melanoma with peritoneal metastases was established. This case high-lights the possibility of a retroperitoneal malignant melanoma exerting a mass effect on thesurrounding organs. The authors suggest that malignant melanoma should be taken into consid-eration as a possible differential diagnosis of retroperitoneal neoplasms.Copyright ª 2013, Taiwan Genomic Medicine and Biomarker Society. Published by ElsevierTaiwan LLC. All rights reserved.

of Surgery, Kaohsiung Medical University Hospital, Kaohsiung Medical University, 100 Tzyou 1st Road,

inet.net (J.-Y. Wang).

an Genomic Medicine and Biomarker Society. Published by Elsevier Taiwan LLC. All rights reserved.3.08.001

114 C.-F. Chen et al.

Introduction

Melanomas are derived from melanocytes, which origi-nate from the neural ectoderm and migrate to the skin,eyes, and leptomeninges in early embryonal life.1

Compared with most malignant melanoma that occursprimarily in the skin, fewer than 10% of malignant mel-anomas arise from noncutaneous regions, including thechoroid layer of the eyes, the leptomeninges, oral mu-cosa, and the mucosa of the gastrointestinal, respira-tory, and genitourinary tracts.2 Malignant melanomaarising in the retroperitoneum is extremely rare. Here,we report a case with ileus secondary to a huge retro-peritoneal malignant melanoma and briefly review theliterature.

Figure 1 Abdominal computed tomography scan of the pri-mary retroperitoneal malignant melanoma. (A) A retroperito-neal tumor with irregular margin, heterogenous density,measured approximately 18.2 � 21.5 cm in the largest section.(B) The tumor extended cross-midline of the abdomen,partially enclosing the left common iliac artery (arrow).

Case report

A 77-year-old woman visited our department of emer-gency due to progressive abdominal fullness anddecreased appetite over the previous 4 months. In addi-tion, she complained of nausea and vomiting in the pre-vious 3 days. She had underlying diabetes mellitus as wellas ischemic heart disease, and lived in a nursing home.General physical examination revealed abdominaldistension and hypoactive bowel sound, but no abdominaltenderness. Plain films showed soft-tissue density in theleft lower quadrant of the abdomen, as well as rightwarddisplacement of the intestine. Laboratory data excludedany metabolic or septic causes of ileus. Abdominalcomputed tomography (CT) scan identified a huge retro-peritoneal tumor with irregular margin, heterogenousdensity, and invasion of the left lower peritoneal spaceanteroinferiorly. The mass measured approximately18.2 � 21.5 cm in the largest section (Fig. 1A) and wasclearly separable from the pancreas, kidney, and bilateraladrenal glands. The tumor extended cross-midline of theabdomen, partially enclosed the left common iliac artery(Fig. 1B), and was inseparable from the left psoas muscle.The patient underwent minilaparotomy thereafter. Wenoted that the gross appearance of the mass was soft andgray-white in color (Fig. 2A). The tumor had a paren-chymal green-black necrotic area as well as a bleedingtendency. Multiple metastatic lesions were noted over thevisceral and parietal peritoneum (Fig. 2B). We checkedthe small intestine carefully during the operation and noobvious intestinal mass lesions were identified. Inconsideration of the patient’s intraoperative critical he-modynamics and late stage of the malignancy, we per-formed incisional biopsy instead of en bloc resection ofthe tumor as well as the peritoneal lesions. The specimenwas evaluated by histologic analysis and immunohisto-chemical staining. Microscopic study revealed abundanttumor necrosis, high nuclear/cytoplasmic ratio, andhypercellularity; with spindle or irregular nucleoli intumor cells (Fig. 3A). The cells showed positive stainingfor S-100 protein (Fig. 3B), human melanoma black-45(HMB-45; Fig. 3C) and vimentin (Fig. 3D), whereas cyto-keratin AE1/AE3, cytokeratin 7, epithelial membrane an-tigen, and CD34 were negative. Therefore, the diagnosis

of malignant melanoma with peritoneal metastases wasestablished. The detailed history revealed that the pa-tient had no previous melanoma. Subsequently, she wasreferred for further dermatologic and ophthalmologicexamination, and no suspicious primary lesion was iden-tified. Further investigations were also scheduled, but thepatient declined to receive subsequent examinations. Dueto poor nutritional status on admission, she receivedpostoperative nutritional support therapy prior to furthertreatment of the Stage IV malignant melanoma. However,systemic chemotherapy was postponed because the pa-tient developed pneumonia in the postoperative course.Consequently, she died 2 months after surgery.

Discussion

Primary retroperitoneal neoplasm includes a diverse groupof benign and malignant tumors that arise in the retro-peritoneum. Due to the inaccessibility of the region andbecause these tumors are often asymptomatic until theyhave reached a substantial size, they are usually large atpresentation.3 Therefore, diagnosis and management of

Figure 2 Intraoperative findings. (A) The surface of thetumor was gray-white in color grossly (double arrows). (B) Oneof the peritoneal metastatic lesions was identified over themesentery (single arrow).

Ileus caused by retroperitoneal malignant melanoma 115

these tumors is often challenging for clinicians because oftheir clinical features.

The most common symptoms in patients with retro-peritoneal tumors remain nonspecific, including earlysatiety, anemia, abdominal swelling, abdominal pain, andback pain.4e6 Additionally, patients may also present witha palpable abdominal mass. The most common histologyof primary retroperitoneal malignant tumors is lip-osarcoma, followed by leiomyosarcoma.4 By contrast,malignant melanoma arising in the retroperitoneum isextremely rare.

In this case report, we present a case with ileus sec-ondary to a huge retroperitoneal malignant melanoma. Areview of the literature was performed using PubMed withthe keywords “malignant melanoma” and “retro-peritoneum” to search for all case reports and reviewspublished between 1963 and 2013 on malignant melanomaoriginating from the retroperitoneal space. Similar searcheswere performed using Ovid MEDLINE. A solitary retroperi-toneal malignant melanoma with a maximal diameter>20 cm at diagnosis has not been previously reported in theliterature. Most cases reported so far with primary retro-peritoneal malignant melanoma are of the adrenal medullaorigin.7,8 There are only seven cases reported to date as a

primary retroperitoneal malignant melanoma that origi-nated from retroperitoneal tissue other than the adrenalgland.8e13 Because of their rarity, the epidemiology andclinical behavior of these tumors have not been wellcharacterized.

Regarding the possible etiology of primary retroperi-toneal malignant melanoma, several authors havepointed out that melanoma lesions may arise from theadrenal glands, lumbar sympathetic chains, and auto-nomic nerve plexuses.7,10 The findings may explain whymelanoma can arise within the retroperitoneal space.Previous studies have reported that primary retroperi-toneal malignant melanoma can cause a mass effect onthe surrounding organ.7,8,11,12 It is interesting to notethat the findings in the current case, like a solitary bulkytumor with a mass effect, are coincident with previouscase reports of primary retroperitoneal melanoma. Mostretroperitoneal metastatic melanomas (i.e., pancreas,kidney, lymph nodes) are usually multiple and smalllesions.14

Diagnosis of malignant melanoma in the abdomen isgenerally made by radiographic studies, histopathologicanalysis, and immunohistochemical stains. Abdominal CTscan is currently the most widely used imaging method fortumor staging, preoperative surveillance, and a follow-upto therapeutic response.15 However, a final diagnosis ofmalignant melanoma can only be made after histopatho-logic and immunohistochemical analysis. Cytologic featuresof malignant melanoma include enlarged nuclei, prominentnucleoli, thick and irregular nuclear membranes, abnormalcytoplasmic melanization, and atypical mitotic figures.1

Histologically, tumor cells may be classified into four celltypes: epithelioid, spindle cell, lymphoma-like, and pleomorphic.16

Immunohistochemical stains are now widely used for thediagnosis of malignant melanoma. Extracutaneous mela-nomas exhibit the same immunohistochemical and ultra-structural features as their cutaneous counterparts.11 S-100protein, HMB-45, melanin A, vimentin, and occasionallyantityrosinase antibodies are used as immunohistochemicaltools in the diagnosis of melanoma. S-100 protein is themost common screening immunohistochemical stain used inthe diagnosis of melanoma and it remains the most sensi-tive marker for melanocytic lesions (sensitivity nearly100%).16e18 Other markers such as HMB-45, melanin A,vimentin, and antityrosinase antibody demonstrate rela-tively good specificity but not the same sensitivity as S-100.18,19 The sensitivity of HMB-45 for melanoma is re-ported to reach 93e100%, with a distribution similar to thatof melanin A,11 and the reported sensitivity of vimentin is93%.16 Along with the wide application of immunohisto-chemical stains, Tousignant et al20 reported that simulta-neous positivity for S-100 protein and vimentin, confrontedwith the patient’s history and with histologic features,firmly establishes the diagnosis of malignant melanoma invirtually all cases.

In conclusion, we report a case with ileus secondary toa huge primary retroperitoneal malignant melanoma.This case highlights the possibility of a retroperitonealmalignant melanoma exerting a mass effect on the sur-rounding organs. Finally, the authors suggest that ma-lignant melanoma should be taken into consideration as a

Figure 3 Histologic and immunohistochemical analysis. (A) Hematoxylin and eosin stain (�400) showed high nuclear/cytoplasmicratio and hypercellularity, with spindle or irregular nucleoli in tumor cells. (BeD) Immunohistochemical analysis demonstratedpositive staining with S-100 protein (B, �400, arrow), HMB-45 (C, �400, arrow), and vimentin (D, �400, arrow).

116 C.-F. Chen et al.

possible differential diagnosis of retroperitonealneoplasm.

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