• Benjamin J Van Treeck, Surendra Dasari, Paul J Kurtin, Jason D Theis, Samih H Nasr, Lizhi Zhang, Saba Yasir, Rondell P Graham, Ellen D McPhail, and Samar Said.
• Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA.
• Amyloid. 2022 Mar 1; 29 (1): 58-63.

ObjectiveTo report the clinicopathologic and proteomic characteristics of a novel form of amyloidosis derived from the precursor protein somatostatin.Materials And MethodsCases were identified by searching the Mayo Clinic amyloid liquid chromatography and tandem mass spectrometry (LC-MS/MS) typing database from 1 January 2008 to 1 September 2020 for specimens with the amyloid signature proteins and abundant somatostatin, in the absence of other amyloid precursor proteins. All available medical records and pathologic materials were examined.ResultsSomatostatin-derived amyloid deposits were found in four patients, two females and two males, with a median age of 61.5 years (range 47-73 years). One patient also had neurofibromatosis-1. The amyloid in each case was associated with a well-differentiated, somatostatin-producing neuroendocrine tumour arising in the small bowel or pancreas. The amyloid deposits were Congo Red-positive and were readily identified by LC- MS/MS analysis. Somatostatin was present exclusively in somatostatin-associated amyloid cases (p < .001), compared to small bowel and pancreas amyloidosis cases of other types. Long-term follow-up is available for one patient who is alive 6 years after initial presentation.ConclusionWe propose that somatostatin-related amyloidosis is a novel localised human amyloid type that arises in association with well-differentiated somatostatin-producing enteropancreatic neuroendocrine tumours. Treatment of the associated neuroendocrine tumour may be adequate therapy for these patients.

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