Keela Scott, MD, Caitlyn J. Smith, BS, Deepthi Rao, MD University of Missouri, Columbia, MO
Introduction: Metastatic melanoma involving the gastrointestinal-tract is rare. Previous studies reported that the most common primary malignancy leading to the stomach's metastatic tumor was melanoma (27%). Another study demonstrated that Amelanocytic melanomas(AM) comprised only 9.8% of melanomas, which typically affected the face, and extremities, and conferred a worse prognosis.
Methods: A retrospective review of patient records between 2000 and 2020 was performed. Further investigation was conducted to evaluate clinical and microscopic findings.
Results: Our investigation identified seven patients with gastric metastatic melanoma. M:F ratio was 5:2. The mean age was 66.6 years (range 63 to 77 years). Interestingly, 86% (6/7) of the cases presented with gastric ulceration (Figure A). Remarkably, 57% of these cases were amelanocytic while only 43% were melanocytic (Figure B). The average time between initial diagnosis of melanoma and gastric metastasis was 12.8 months. Of note, two of seven patients presented with metastatic melanoma to the stomach with unknown primaries. Various morphologies were identified including epithelioid (71%), spindle (14%), and mixed epithelioid and spindle (14%). Lastly, 57% of the tumors presented with a diffuse, infiltrative pattern, while 43% presented as distinct mass lesions.
Discussion: AM presents an especially challenging scenario in the evaluation of metastatic disease to the stomach. The true prevalence of this malignancy may be greater due to misdiagnosis. Thus, there should be high suspicion for this entity when evaluating gastric specimens for metastatic disease. Further molecular studies are needed to understand the possible underlying mechanisms leading to gastric metastasis in melanoma, especially the AM given its higher propensity.
Figure: Gastric metastatic melanoma. Gastric ulceration (Figure A). Metastatic amelanocytic melanoma to the stomach (Figure B).
Disclosures:
Keela Scott indicated no relevant financial relationships.
Caitlyn Smith indicated no relevant financial relationships.
Deepthi Rao indicated no relevant financial relationships.
Keela Scott, MD, Caitlyn J. Smith, BS, Deepthi Rao, MD. B0694 - Do Amelanotic Melanomas Have a Higher Propensity to Metastasize to Stomach?, ACG 2022 Annual Scientific Meeting Abstracts. Charlotte, NC: American College of Gastroenterology.
