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

• Published in: Diagnostic pathology 2020-07, Vol.15 (1), p.81-81, Article 81
• Main Authors: Venable, Elise R, Kerr, Sarah E, Lopes, M Beatriz S, Jones, Karra A, Bellizzi, Andrew M, Mounajjed, Taofic, Raghunathan, Aditya, Hamidi, Oksana, Halfdanarson, Thorvardur R, Ryder, Mabel, Graham, Rondell P
• Format: Article
• Language: English
• Subjects: Abdomen; Adrenocorticotropic hormone; Aged; Automation; Biomarkers, Tumor - metabolism; Biopsy; Brain cancer; Cancer; Cancer metastasis; Carcinoma; CDX2 protein; Cellular biology; Corticotropin; Cushing syndrome; Diagnosis, Differential; Differential diagnosis; Female; Humans; Immunohistochemistry; Liver; Liver metastasis; Liver Neoplasms - diagnosis; Liver Neoplasms - secondary; Male; Metastases; Metastasis; Middle Aged; Mimicry; Nervous system diseases; Neuroendocrine tumor; Neuroendocrine tumors; Neuroendocrine Tumors - diagnosis; Pancreas; Patients; Pituitary; Pituitary (anterior); Pituitary carcinoma; Pituitary gland; Pituitary Neoplasms - diagnosis; Pituitary Neoplasms - secondary; Pituitary tumor; Tumors
• ISSN: 1746-1596; 1746-1596
• DOI: 10.1186/s13000-020-00997-x

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. In contrast, pituitary carcinoma is very rare, and there is limited data on its natural history and pathologic characterization. The 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. All 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. Frequently, 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.