Primary Gastric Mucosal Melanoma: A Rare Etiology of Iron Deficiency Anemia.

Iron deficiency anemia is a concerning finding, particularly in males and post-menopausal females, and can have numerous underlying causes. When evaluating potential sources of gastrointestinal blood loss, bidirectional endoscopy is often necessary. We report the case of an 89-year-old female with multiple comorbidities, including atrial fibrillation treated with apixaban, who presented with symptomatic iron deficiency anemia. Extensive dermatological and radiological assessments ruled out a primary source, and subsequent endoscopy identified a rare etiology: primary gastric mucosal melanoma. This case highlights the importance of thorough evaluation in identifying uncommon causes of iron deficiency anemia such as unsuspected malignancies, hereditary conditions, and different autoimmune conditions amongst other etiologies.

Wandering Mucosal Melanoma Presenting as Occult Gastrointestinal Blood Loss Anemia.

Malignant melanoma is a highly aggressive cancer arising from the skin, retina, and mucosal lining of the respiratory, gastrointestinal (GI), or genitourinary tracts, all of which contain melanocytes. Mucosal or extracutaneous melanomas (ECMs) are rare accounting for 1% of all melanomas. We herein report a case of a metastatic mucosal melanoma presenting as occult blood loss anemia. A 58-year-old male presented with generalized weakness, anorexia, weight loss, and intermittent melena for one year. On exam, he was tachycardic, borderline hypotensive, and pale without epigastric tenderness. Labs showed severe anemia [hemoglobin, Hgb 3.8 mg/dL, mean corpuscular volume (MCV) 72 fl] for which he received two units of red cells. Endoscopy revealed an 8 mm non-bleeding, gastric ulcer with a raised border and a clean base on the wall of the gastric body. Histologic analysis was consistent with malignant melanoma displaying strong positivity for S-100, Melan A, and HMB 45 stains. The CT of the abdomen revealed multifocal metastatic disease with subcutaneous, intramuscular, and perinephric implants with suspicion of small bowel carcinomatosis. The patient underwent an excisional biopsy for the abdominal wall mass and surgical pathology confirmed melanoma. The patient is planned to be started on immunotherapy for advanced disease. Most melanomas found in the GI tract are metastatic. Mucosal melanoma presenting as a gastric ulcer is extremely rare. As a result, metastasis from other sites must be ruled out before making a diagnosis of primary gastric melanoma (PGM). In our case, a widespread disease with unknown primary elucidated the diagnosis but post-operative inspection failed to find any potential lesion on the skin, genitals, or other organs, suggesting the possible diagnosis of metastatic gastric melanoma. However, follow-up is still required to confirm the diagnosis according to the established criteria. Pathologic diagnosis of melanoma requires the identification of melanin in the cytoplasm and immunohistochemistry with specific markers such as S-100, Melan A, and HMB-45. Although the pathologic diagnosis of PGM is similar to cutaneous melanoma, preoperative diagnosis is difficult due to the extremely low incidence, lack of obvious melanin pigmentation, similar microscopic patterns as more common gastric cancers, and lack of awareness among physicians and pathologists. The prognosis of mucosal melanoma is poor, with a five-year survival rate of 25% versus 80% for cutaneous melanoma. Advanced age, surgically unresectable disease, and lymph node involvement are all poor prognostic markers. There is no standard protocol for treatment. Surgery is the only curative treatment for the resectable disease. Adjuvant chemotherapy, radiation, and immunotherapy have an established role in cutaneous melanoma but there is only limited data on adjuvant systemic therapy with mucosal melanoma. Further research is imperative to establish proper management guidelines for this rare disease entity.

Primary Gastric Malignant Melanoma.

Primary gastric malignant melanoma (PGMM) is an extremely rare clinical entity, and few cases have been described in the literature. Here, we report a histologically confirmed PGMM case of a 74-year-old man with a mass in the stomach found by gastroscopy. The patient had no history of melanoma. This rare disease may be misdiagnosed for another gastric malignant tumor type when there is no known primary lesion. Early detection and surgical intervention are critical for long term survival or cure, though the tumor is often advanced at the time of diagnosis and is associated with a dismal outcome.

Primary gastric malignant melanoma: challenge in preoperative diagnosis.

Primary gastric melanoma is an extremely rare clinical entity. The clinical manifestation is not specific and usually similar with other common malignancies at this site, such as gastric cancer and lymphoma. And there are no specific radiological features either. Preoperative diagnosis via biopsy is usually difficult, since melanoma pigment could be absent in the biopsy tissue. Here, we report a case of a 50-year-old woman with a mass in the stomach found by gastroscopy. Biopsy was taken twice preoperatively under gastroscope and it was diagnosed as gastric carcinoma and neuroendocrine tumor respectively. Radical surgery was performed with gastrectomy and D2 lymph node dissection. Postoperative pathological examination finally made a definite diagnosis of gastric melanoma by immunohistochemistry. We summarize the reasons for preoperative misdiagnosis and discuss the difficulty in diagnosing gastric melanoma according to literature.