Liver metastases from pituitary carcinomas mimicking visceral well-differentiated neuroendocrine tumors: a series of four cases

Elise R Venable,Thorvardur R Halfdanarson,Sarah E Kerr,Karra A Jones,M Beatriz S Lopes,Aditya Raghunathan,Rondell P Graham,Oksana Hamidi,Taofic Mounajjed,Mabel Ryder,Andrew M Bellizzi

doi:10.1186/s13000-020-00997-x

Abstract

BackgroundPathologists frequently encounter neuroendocrine tumors (NETs) presenting as multiple liver masses in routine practice. Most often, these are well-differentiated tumors with characteristic histologic features. In contrast, pituitary carcinoma is very rare, and there is limited data on its natural history and pathologic characterization.MethodsThe aim of this study was to describe clinical characteristics, histomorphology, immunophenotype and follow-up of pituitary carcinoma involving the liver and mimicking well-differentiated NETs of visceral origin. We selected a group of well-differentiated NETs of the pancreas to use as immunophenotypic controls. We identified 4 patients (age range, 51 to 73) with pituitary corticotroph carcinoma with liver metastases. Three patients presented with Cushing syndrome.ResultsAll cases histologically resembled well-differentiated NETs of visceral origin with Ki-67 proliferation indices of 5–42% and expression of T-PIT; metastatic tumors were not immunoreactive with CDX2, Islet 1 or TTF-1.ConclusionsFrequently, these cases display adrenocorticotropic hormone (ACTH) secretion and pituitary-specific transcription factor immunohistochemistry may be used as a reliable marker to distinguish metastatic pituitary carcinoma from NETs of visceral origin in addition to delineating a corticotroph carcinoma from somatotroph, lactotroph, thyrotroph, and gonadotroph lineage. Although rare, the differential diagnosis of pituitary carcinoma should be considered in metastatic well-differentiated NETs in which the site of origin is uncertain. In summary, pituitary corticotroph carcinoma can metastasize to the liver and mimic well-differentiated NET.

Highlights

Pathologists frequently encounter neuroendocrine tumors (NETs) presenting as multiple liver masses in routine practice
Pituitary carcinomas deriving from the adenohypophysis are exceedingly rare accounting for 0.1–0.5% of all pituitary tumors with only limited reports of its natural history [14, 15]
2 cases were identified in a single year and the initial clinical concern was for involvement by well-differentiated NET of gastroenteropancreatic or visceral origin

Summary

Introduction

Pathologists frequently encounter neuroendocrine tumors (NETs) presenting as multiple liver masses in routine practice. Most often, these are well-differentiated tumors with characteristic histologic features. When a metastatic neuroendocrine tumor is identified, the primary sites typically considered are the GI tract and pancreas followed by lung. These are typically well-differentiated tumors with characteristic cytomorphologic and/or histologic features. In our practices we have encountered rare cases of pituitary carcinoma metastatic to the liver simulating well-differentiated neuroendocrine tumors (NETs). The aim of this study was to describe the clinicopathologic features of a series of pituitary corticotroph carcinomas involving the liver and mimicking welldifferentiated neuroendocrine tumors of visceral origin

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