Neuroendocrine/Small Cell Carcinoma

Neuroendocrine/Small Cell Carcinoma
Histologic features of neuroendocrine differentiation include an organoid growth pattern with uniform epithelioid cells having moderate amounts of cytoplasm, dispersed chromatin, and rosette formation.
Neuroendocrine breast carcinoma must express a neuroendocrine marker such as chromogranin in ≥ 50% of tumor cells image. Normal breast epithelial cells are negative for these markers image.
TERMINOLOGY
Abbreviations
  • Neuroendocrine breast carcinoma (NEBC)
    • Solid neuroendocrine breast carcinoma (SNEBC)
    • Small cell/oat cell breast carcinoma (SCOCBC)
    • Large cell neuroendocrine breast carcinoma (LCNEBC)
Synonyms
  • Invasive carcinoma with endocrine differentiation (argyrophilic carcinoma)
  • Mammary carcinoma with endocrine features
Definitions
  • WHO classification recognizes 3 categories of neuroendocrine breast carcinoma
    • Solid neuroendocrine breast carcinoma
    • Small cell/oat cell breast carcinoma
    • Large cell neuroendocrine breast carcinoma
  • Carcinomas must have “morphologic features similar to those of neuroendocrine tumors of both gastrointestinal tract and lung”
    • Tumors must express at least 1 neuroendocrine marker in > 50% of cells to qualify
  • Some carcinomas with typical morphologic appearance will not express neuroendocrine markers
  • Alternatively, not all carcinomas that express neuroendocrine markers have a distinctive morphologic appearance
  • This is a heterogeneous group of carcinomas; not all cases will easily fit into 3 groups as defined by WHO
ETIOLOGY/PATHOGENESIS
Biology of NEBC
  • Gene expression profiling analysis of NEBC
    • NEBC belongs to luminal A subgroup
    • SNEBC has transcriptional pattern identical to type B mucinous carcinoma (hypercellular type)
    • This association is present whether or not mucinous carcinomas express neuroendocrine markers
    • Type A mucinous carcinomas (paucicellular) cluster in separate but related group
CLINICAL ISSUES
Epidemiology
  • Incidence
    • NEBCs comprise 2-5% of breast carcinomas
  • Age
    • NEBC has same age distribution as carcinomas of no special type; median age at diagnosis is 61 years
Presentation
  • NEBC usually presents as palpable mass or mammographic density
    • Calcifications have not been associated with these tumors
  • Very rare breast carcinomas produce ectopic hormones
    • Human chorionic gonadotropin, calcitonin, adrenocorticotrophic hormone, parathormone, and epinephrine have been reported
    • Clinical symptomatology from these hormones is very rare
Treatment
  • Not altered by presence of neuroendocrine markers
Prognosis
  • Information is limited due to small numbers of patients and varying definitions of NEBC
  • In small studies, SNEBC, especially if associated with solid papillary pattern or mucin production, has better prognosis
  • In 1 study, LCNEBC had worse prognosis compared to matched controls with carcinomas of no special type
IMAGE FINDINGS
Radiographic Findings
  • No specific imaging features
MACROSCOPIC FEATURES
General Features
  • No specific gross features
MICROSCOPIC PATHOLOGY
Histologic Features
Jul 6, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Neuroendocrine/Small Cell Carcinoma

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