Thymic neuroendocrine tumor

Carcinoid tumor

Last author update: 1 December 2012
Last staff update: 1 March 2023

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PubMed Search: Carcinoid tumor mediastinum

Hanni Gulwani, M.B.B.S.
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Cite this page: Gulwani H. Carcinoid tumor. website. Accessed June 8th, 2023.
Definition / general
  • Similar to carcinoid tumors elsewhere
  • Also called well differentiated neuroendocrine carcinoma
  • Usually of thymic origin in anterior mediastinum, occasionally in middle or posterior mediastinum
Diagrams / tables

Images hosted on other servers:

Features of 4 patients
(tables 1 and 3)

Clinical features
  • Mean age 48 years old, 80% men
  • 20% occur in MEN1 or MEN2 patients
  • One - third have paraneoplastic Cushing syndrome, syndrome of inappropriate antidiuretic hormone, Eaton-Lambert syndrome or rarely PTH production (Ann Thorac Surg 2002;73:675)
  • Coexisting carcinoid syndrome is very unusual
  • Behavior similar to atypical carcinoid at other sites; must be considered to have metastatic potential with metastasis to mediastinal lymph nodes, bone, liver, skin
  • May recur after up to 10 years
Prognostic factors
  • Poor prognosis (Korean J Pathol 2012;46:221)
  • Poor prognostic factors: ectopic ACTH production or association with MEN syndromes
  • 5 year survival: 70% without endocrinopathy versus 35% with endocrinopathy
Case reports
  • Aggressive, presents at advanced stage; complete surgical resection with postoperative radiotherapy to tumor bed is recommended (Interact Cardiovasc Thorac Surg 2010;11:732)
  • Radiation therapy and chemotherapy are ineffective
Gross description
  • Well circumscribed but unencapsulated, firm, gray-pink, fleshy, gritty on cut section, hemorrhage, necrosis, no internal fibrous septa
Microscopic (histologic) description
  • Organoid pattern with islands, ribbons, festoons, trabeculae, rosettes of small round cells with minimal cytoplasm, salt and pepper chromatin, no / rare mitotic activity
  • Cellular nests may become detached from septa during processing and contain foci of central geographic necrosis with dystrophic calcification
  • Marked vascularization, frequent angiolymphatic invasion, may have amyloid type stroma, sclerotic (desmoplastic type) stroma, melanin pigment, mucin
  • May coexist with sarcomatoid carcinoma, thymoma, thymic cyst
  • No lymphocytes, no perivascular spaces
Microscopic (histologic) images

Case #278

Atypical carcinoid

Atypical carcinoid -
AE1 / AE3

Atypical carcinoid - synaptophysin

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Figures a - d

Thymic carcinoid

Atypical carcinoid

Various stains

Positive stains
Electron microscopy description
  • Numerous dense core neurosecretory granules, perinuclear whorls of intermediate filaments, intercellular junctions
  • No complex nucleoli, no premelanosomes, no branching surface microvilli, no complex desmosomes, no tonofilaments
Differential diagnosis
Spindle cell carcinoid of thymus
Clinical features
  • Very rare
  • May cause death
  • Associated with MEN1, syndrome of inappropriate antidiuretic hormone secretion
  • Aggressive clinical behavior (Mod Pathol 1999;12:587)

Case reports
Gross description
  • Tan-brown, well circumscribed, encapsulated, 2 - 15 cm

Microscopic (histologic) description
  • Fascicles of plump spindle cells separated by thin fibrovascular septa
  • Amphophilic and granular cytoplasm, finely dispersed chromatin
  • Frequent mitotic figures, frequent focal necrosis
  • No / vague organoid pattern, no prominent nucleoli

Positive stains
Electron microscopy description
  • Neurosecretory granules
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Image 01 Image 02