Medullar carcinomas represent 3 to 10% of malignant tumors of the thyroid. Their prognosis is generally worse than papillary and follicular carcinomas, but much better than for undifferenciated carcinomas. Most frequently they occur sporadically, but in about 20% of the cases they occur in familiar forms, with an autosomal dominant pattern of inheritance called MEN (multiple endocrine neoplasia).

Medullar carcinoma of the thyroid stem from parafollicular interstitial C cells. They are associated with follicular cells, on the basal membrane, either isolated or in small groups. They produce calcitonin, a hormone that lowers the level of seric calcium. It acts at the level of the bone, the kidney and the gastrointestinal tract. It protects the skeleton in periods of need in calcium (growth, pregnancy, lactation). High seric levels of CEA (carcinoembryonic antigen) are also found in medullar carcinoma.

Usual routine histologic staining do not demonstrate C cells. These cells contain cytoplasmic eosinophilic or basophilic secretory granules, only seen with MGG staining. Grimelius staining shows their argyrophilia. C cells are part of the neuroendocrine cell group. These cells are widely distributed throuthout the body and share morphological and biochemical similarities. Whilst they are not all embryologically neural crest derived. They are also called APUD cells (amine precursor uptake decarboxylation).

Amyloid deposits often form between tumor cells and conjonctive septa. This is an amorphous purple stained substance with MGG. These deposits exhibit yellow-green birefringence in polarized light. Sometimes amyloid deposits induce foreign body reaction with giant cells.

In cytology, the cells are typically spindle-shaped, in cohesive groups. Important anisonucleosis can be observed. Binucleation and plasmacytoid aspect (triangular cells with excentric nuclei) are also a typical criteria. MGG staining allows small cytoplasmic basophilic or eosinophilic granulations to be seen.

-54 year old woman.

 
  Spindle-shaped tumor cells with coarsely clumped chromatin, and basophilic cytoplasm (MGG).  
       
  Spindle-shaped tumor cells on imprint smear (PAP).  
       
  Marked anisonucleosis and coarse chromatin (MGG).  
       
 
Binucleated tumor cells
   
       
 
Triangular tumor cells with eccentric nucleus. Basophilic granulations on MGG (left).
    
       
  Amyloid deposits surrounded by tumor cells (PAP).  
       
  In histology too, cells focally display a spindle-shaped aspect.  
       
 
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Dernière mise à jour: le 31 janvier, 2004
   
 

Pour en savoir plus:

Droese M: Cytological Aspiration Biopsy of the Thyroid Gland. F.K. Schattauer Verlag, Stuttgart-New-York, 1980.

Kini SR: Guides to Clinical Aspiration Biopsy. Thyroid. Igaku-Shoin, New-York-Tokyo, 1987.

LiVolsi VA: Surgical Pathology of the Thyroid. Major problems in pathology, vol 22. W.B. Saunders Co, Philadelphia, 1990.

Miller JM, Kini SR, Hamburger JI: Needle Biopsy of the Thyroid. Praeger 1983.

Meissner WA, Warren S: Tumors of the Thyroid Gland. Atlas of tumor pathology fascicle 4. Armed Forces Institute of Pathology, 1969.

Rosai J, Carcangiu ML, DeLellis RA: Tumors of the Thyroid Gland. Atlas of tumor pathology fascicle 5. Armed Forces Insitute of Pathology, 1992.

Papaparaskeva K, Nagel H, Droese M: Cytologic diagnosis of medullary carcinoma of the thyroid gland. Diagn Cytopathol 22(6):351-358, 2000.

Kaserer K, Scheuba C, Neuhold N: C-Cell hyperplasia and medullary thyroid carcinoma in patients routinely screened for serum calcitonin. Am. J. Surg. Pathol. 22(6):722-728, 1998.

Forrest CH, Frost FA, de Boer WB: Medullary carcinoma of the thyroid. Accuracy of diagnosis by fine-needle aspiration cytology. Cancer (Cancer-Cytopathol)84(5):295-302, 1998.

Galera-Davidson H: Diagnostic problems in thyroid FNAs. Diagn Cytopathol 17(6):422-428, 1997.