Cutaneous Metastasis of Gastroenteropancreatic Neuroendocrine Tumors (GEP-Nets).

Background: Gastroenteropancreatic neuroendocrine tumors are neoplasms commonly found within the gastrointestinal tract that originate from endocrine cells. These are slow progressive tumors and often metastasize to other elements of the gastrointestinal tract including the liver. Consequently, these tumors release hormones including serotonin and/or histamine that are responsible for the symptoms including intermittent flushing and diarrhea. Metastasis of gastroenteropancreatic neuroendocrine tumors, although rare, is possible and may extend to local lymph nodes and viscera.

Case report: Our patient was a 69-year-old female who initially presented with postprandial abdominal pain, nausea, vomiting, and later was diagnosed with gastroenteropancreatic neuroendocrine tumors following surgical resection in 2014. Restaging after surgery showed regional lymph node involvement and hepatic metastasis. Of note she did not have a pre-operative computed tomography scan. She was started on octreotide, and later switched to lanreotide. In the interim, she did not have any positive findings on serial octreoscans depicting the skin lesion that was performed in the interim period every six months. However, she noticed a cutaneous mass in the upper right flank mass in 2016, which was followed up by a dermatologist. In 2017, the mass grew in size and hence biopsied which showed neuroendocrine tumors consistent with her primary tumor.

Discussion: Gastroenteropancreatic neuroendocrine tumors often metastasize to lymph nodes and liver but rarely can involve the skin and present as firm papules as found in our patient. Cutaneous metastasis of gastroenteropancreatic neuroendocrine tumors often has high morbidity and mortality and is usually associated with a primary lesion in the bronchopulmonary system. However, as demonstrated in this case report, cutaneous metastasis can originate from the gastrointestinal tract, including the small intestine as well.