An 80-year-old man with a history of Merkel cell carcinoma of the right upper extremity with involvement of 2 local lymph nodes treated with excision and radiation 2 years ago presented with 4 days of progressive fatigue, pre-syncope, and melena. Physical examination revealed diffuse pallor, orthostatic hypotension, and black, guaiac-positive stool. Coffee-ground material was appreciated on gastric lavage. Initial laboratory work showed a hemoglobin level of 7.7 g/dL and a hematocrit of 22.6%. Subsequent esophagogastroduodenoscopy revealed a bulky anterior gastric antral mass with a large, penetrating ulcer (Figure A). Histopathologic analysis showed an infiltrate of malignant cells in the lamina propria with increased nuclear to cytoplasmic ratios, scant eosinophilic cytoplasm, finely granular chromatin, multiple nucleoli, and frequent mitoses. Cytokeratin 20 expression on immunohistochemical staining confirmed a diagnosis of metastatic Merkel cell carcinoma (Figure B). Computerized tomography scan revealed diffuse concentric thickening of the stomach (Figure C, small arrows) most prominently in the posterior aspect (Figure C, large arrows) with multiple enlarged perigastric lymph nodes. A positron emission tomography scan showed no other foci of metastatic disease. The patient underwent combined chemoradiation with 4 cycles of carboplatin and etoposide. Positron emission tomography after therapy noted a near-complete gastric response to therapy, however, abdominal wall metastases were noted. He died soon thereafter.View Large Image Figure ViewerDownload Hi-res image Download (PPT)View Large Image Figure ViewerDownload Hi-res image Download (PPT) Merkel cell carcinoma is a rare, aggressive neuroendocrine malignancy of the skin that generally carries a poor prognosis. Sun exposure is thought to be the major risk factor because lesions are found primarily in sun-exposed areas of elderly Caucasians. Reports also have suggested that altered host immune status may play an important etiologic role.1Goessling W. McKee P.H. Mayer R.J. Merkel cell carcinoma.J Clin Oncol. 2002; 20: 588-598Crossref PubMed Scopus (254) Google Scholar Patients typically present with a painless, firm, raised nodule with a flesh or bluish-red appearance on the head, neck, or extremities. Typical sites of metastasis include liver, bone, brain, and skin.2Voog E. Biron P. Martin J.P. et al.Chemotherapy for patients with locally advanced or metastatic Merkel cell carcinoma.Cancer. 1999; 85: 2589-2595Crossref PubMed Scopus (265) Google Scholar This case represents only the fourth documented case in the literature of gastrointestinal metastasis.3Li M. Liu C. Cytokeratin 20 confirms Merkel cell metastasis to stomach.Appl Immunohistochem Mol Morphol. 2004; 12: 346-349Crossref PubMed Scopus (13) Google Scholar, 4Idowu M.O. Contos M. Gill S. et al.Merkel cell carcinoma: a report of gastrointestinal metastasis and review of the literature.Arch Pathol Lab Med. 2003; 127: 367-369PubMed Google Scholar, 5Canales L.I. Parker A. Kadakia S. Upper gastrointestinal bleeding from Merkel cell carcinoma.Am J Gastroenterol. 1992; 87: 1464-1466PubMed Google Scholar Immunohistochemical staining confirms the diagnosis because Merkel cell carcinoma often resembles small-cell carcinoma, melanoma, and lymphoma histologically.1Goessling W. McKee P.H. Mayer R.J. Merkel cell carcinoma.J Clin Oncol. 2002; 20: 588-598Crossref PubMed Scopus (254) Google Scholar Treatment generally includes wide surgical excision of the primary tumor in conjunction with adjuvant radiation therapy and chemotherapy.1Goessling W. McKee P.H. Mayer R.J. Merkel cell carcinoma.J Clin Oncol. 2002; 20: 588-598Crossref PubMed Scopus (254) Google Scholar Formal staging and management guidelines do not exist because of low disease prevalence. The authors give special thanks to Dr. Kimberly Heightchew, MD, Department of Pathology, Mainline Health System.