Thymic carcinoid tumour, well-differentiated thymic neuroendocrine carcinoma

Alomst all carcinoids of the thymus fulfil the criteria for atypical carcinoids.

Clinical features

There is an association with MEN I and with Cushing syndrome2,3. Almost all MEN-associated cases occur in men. Carcinoid syndrome is very rare.

Histopathology

This is a well-differentiated tumour composed of a uniform population of cells forming nests, ribbons, festoons and glands.

Some cases arise from germ cell tumours4.

Immunohistochemistry

 

Typical carcinoid

atypical carcinoid

Cytokeratin

 

11/123, 3/35

EMA

 

1/35

Chromogranin

3/3 (one case only weak)2

5/62, 3/35

Synaptophysin

3/32

5/62, 2/35

Grimelius

 

8/133

NSE

3/32

6/62, 13/133

CD56

3/32

6/6 (one case focal)2

bcl-2

 

2/35

S-100

 

0/133

p53

 

3/133, 1/35

CD5

 

0/35

     

Differential diagnosis

Management

Thymic carcinoids are often not ameneable to complete resection3.

Prognosis

The prognosis is poor, irrespective of grade2, with a median survival of 28 months in one series3. Half of all atypical carcinoids show local invasion or metastases. Distant metaastases are common3.

References

J Rosai et al. Histological typing of tumours of the thymus. WHO International histological classification of tumours. Springer-Verlag, second edition, 1999.

Moran, C. A. and S. Suster (2000). "Thymic neuroendocrine carcinomas with combined features ranging from well-differentiated (carcinoid) to small cell carcinoma. A clinicopathologic and immunohistochemical study of 11 cases." Am J Clin Pathol 113(3): 345-50.

2Tiffet, O., A. G. Nicholson, et al. (2003). "A clinicopathologic study of 12 neuroendocrine tumors arising in the thymus." Chest 124(1): 141-6.

3de Montpreville, V. T., P. Macchiarini, et al. (1996). "Thymic neuroendocrine carcinoma (carcinoid): a clinicopathologic study of fourteen cases." J Thorac Cardiovasc Surg 111(1): 134-41.

4Warren, J. S. and M. N. Yum (1987). "Carcinoid tumor arising in a treated primary germ cell tumor of the mediastinum." South Med J 80(2): 259-61.

5Histopathology 2004;44:367-374.

This page last revised 13.4.2004.

©SMUHT/PW Bishop