Gastric metastases from invasive primary mucosal epithelioid malignant melanoma of the hard palate: report of the first case in the English literature

Abstract

Melanocytes arise from the neural crest and migrate to the epidermis, meninges, uveal tract and ectodermal mucosa. Normal gastric mucosa lacks melanocytes. A 64-year-old woman presented to us with nausea and vomiting. She had a past history of invasive primary mucosal epithelioid malignant melanoma of the hard palate 21 months ago, treated by a wide surgical excision. Gastroscopy revealed multiple punched out ulcers involving the stomach and the first part of duodenum. Immunohistology and clinicopathologic correlation established the diagnosis of metastatic gastric malignant melanoma. To our knowledge, this is the first report in the English literature about gastric metastases arising from primary palatal mucosal melanoma.

Keywords::

• gastric
• melanoma
• metastasis
• oral
• stomach

Financial & competing interests disclosure

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

No writing assistance was utilized in the production of this manuscript.

Key issues

• Cutaneous malignant melanoma has an unusual tendency to metastasize to the gastrointestinal tract.

• Gastric metastases from extracutaneous malignant melanomas are rare events.

• The primary gastric melanomas are exceptional neoplasms. Their clinical manifestations include athenia, abdominal discomfort and weight loss.

• Grossly, primary gastric melanomas appear as ulcerated dark brown, fungating masses.

• Gastric metastatic melanomas are asymptomatic and are usually discovered at autopsy. Clinical presentations are nonspecific and include abdominal pain, nausea, repeated vomiting, weight loss, melena and anemia.

• Gastric metastatic melanomas are slowly growing tumor that may grow extraluminally, making their detection a tedious task. The time interval between the diagnosis of primary malignant melanoma and the diagnosis of gastric metastatic melanomas is variable ranging from few months to several years.

• In oral mucosa, melanocytes are located along the tips and peripheries of the rete pegs. Their function is not clear, and under normal physiological conditions, they do not produce melanin.

• Primary mucosal melanomas arise from melanocytes located in mucosal membranes lining respiratory, urogenital and gastrointestinal tract. They can arise in almost any part of mucosal membranes.

• Most of the mucosal melanomas occur in occult sites and have nonspecific clinical presentations and therefore late diagnosis. These features coupled with their highly vascularized stroma and tendency for lymphovascular invasion contribute to their dismal outcome.

• The differential diagnosis of undifferentiated tumor should include the possibility of malignant melanomas, especially if there is a prior history of melanomas or atypical melanocytic proliferation elsewhere.

• Application of a screening panel is very useful for determination of the lineage of a given undifferentiated malignant neoplasm. This should include: pancytokeratin AE1/AE3 (epithelial marker), Vimentin (mesenchymal marker), S100/HMB45 (melanocytic markers) and CD45 (hematopoietic marker). In certain circumstances, adjuvant immunostains should be added such as CD117 (gastrointestinal stromal tumor), synaptophysin (neuroendocrine marker) and placental alkaline phosphatase (germ cell tumors).