Melanoma metastatic to the appendix is extremely rare. Here we describe a case of a 31-year-old female from Bolivia with a remote history of metastatic malignant melanoma first diagnosed as a cutaneous malignant melanoma ten years prior to this presentation. The patient was being followed for a mucocele which on resection was found to be metastatic melanoma. “Mucocele” is a generic diagnosis that warrants further characterization and treatment.
Malignant melanoma involving the gastrointestinal (GI) tract is a rare condition although it is one of the most common malignancies having the potential to metastasize to the GI tract [
We report a case of malignant melanoma metastatic to the appendix presenting as acute appendicitis in the background of a mucocele.
The patient is a 31-year-old female from Bolivia with a history of melanoma removed from her back ten years prior to this presentation. The pathology report was not available. In November 2005, the patient, now living in the USA, developed increasing headaches, vomiting, and blurred vision. CT scan showed a large left frontal cerebral mass with edema and displacement of the midline structures. The patient then underwent surgical resection of brain tumor which was interpreted as metastatic melanoma. After receiving palliative therapy, the patient enrolled in a chemotherapy trial, Temozolomide along with Sorafenib, at the University of Pennsylvania. Later in 2008, she developed a new 4 mm lesion in right frontal brain lobe. She had no evidence of other metastases. While the patient was being followed by serial CAT scans, a slow growing mass was noted in the appendix approximately one year prior to this presentation, which was interpreted as a mucocele and managed conservatively. In April of 2010, she presented to our institution with symptoms of acute appendicitis. A CT scan of the abdomen and pelvis revealed inflammatory changes and gas in the wall of the distended appendix (Figure
CT scan (coronal view) of the abdomen and pelvis showing an appendiceal mucocele with intraluminal gas and wall edema.
Cloudy peritoneal fluid was noted intraoperatively, and the postoperative diagnosis was gangrenous appendicitis superimposed on a mucocele. She recovered uneventfully.
On gross examination, the appendix was 8.0 cm in length and 1.5 to 3.2 cm in diameter attached to a partial cecectomy. The serosal surface was smooth with areas of hyperemia, and a focal disruption measured 1.5 cm was located in mid appendix. Sectioning revealed an 7.5 cm in length with 1.4–3.0 cm in diameter tumor occupying more than 80% of the appendix. The tumor was soft, pink/tan in the distal aspect, and lobulated green/brown in the proximal portion (Figure
Gross examination: cross-section of appendix, lobulated green/brown partially hemorrhagic, and pigmented tumor occupy the proximal portion of the appendiceal lumen.
On microscopic examination, tumor cells replaced most of the appendiceal mucosa and muscularis with no extension to the serosa. The lesional cells formed nests and cords and had an abundant eosinophilic cytoplasm with mildly pleomorphic nuclei and prominent nucleoli, some of which had intranuclear inclusions (Figures
Microscopic examination: (a) solid cords and nests of tumor cells fill the appendiceal lumen and replace the appendiceal mucosa and submucosa with partial extension to the muscularis, no involvement of the serosa; (b) tumor cells with abundant eosinophilic cytoplasm, some of which are vacuolated, with pleomorphic nuclei, prominent nucleoli, and atypical mitosis (Hematoxylin and eosin staining, (a) x200; (b) x400). (c) Tumor cells strongly express HMB45, and (d) S-100 (HMB45 and S-100 immunostaining, x400).
Malignant melanoma represents 1–3% of all cancer in the USA [
Melanocytes are normal residents of the mucous membranes of the upper aerodigestive tract, gastrointestinal, and urogenital tracts [
Metastatic melanoma has been observed in almost all regions of the human body. The most common sites of metastases were the lymph nodes (74%) and lungs (71%), followed by the liver (58%), brain (55%), bone (49%), adrenal glands (47%), and GI tract (44%), but only 1% to 4% of them are diagnosed antemortem [
We found one reported case describing a malignant melanoma in the vicinity of the appendix. The reported case was that of a 55-year-old Caucasian woman with no available medical history who presented with abdominal pain. Ultrasound suggested a periappendicular abscess or a tumor, but no other intraabdominal lesion was identified. The tumor cells in that case were positive for Melan-A, S-100, HMB45, and vimentin. No primary source of melanoma in this case was evident [
The prognosis of metastatic GI malignant melanoma is very poor with a 5-year survival of less than 10% [
Preoperative diagnosis of appendiceal metastases from malignant melanoma is difficult but should be considered in any patient with a history of melanoma who develops GI symptoms, even in the absence of radiographic findings. Mucocele of the appendix should be managed with resection to ascertain its pathologic features and prevent pseudomyxoma peritonei or other complications.