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Endocrine Pathology Online

Pathology of Follicular Thyroid Carcinoma

Dr Sampurna Roy MD




Full thickness capsular transgression and or vascular invasion in or beyond the capsule,

are the absolute defining features for follicular carcinoma of the thyroid gland.

Since this is an architectural feature which may not be evident until many blocks are

examined, frozen section is not recommended  in diagnosis of follicular thyroid lesions.

Subdivision into minimally invasive and widely invasive subtypes (obvious

macroscopic invasion) is prognostically useful as is grading.

Beware of the rare non-encapsulated variant which may be widely invasive without

any capsule in which to see the invasion.

Where histological features of papillary carcinoma are also present, the diagnosis

becomes that of follicular variant papillary carcinoma, which behaves as papillary


True vascular invasion must be distinguished from impaction of tumour cells into

vessels at cut-up.

Elastin stains and immunohistochemistry for endothelial markers are possibly

overrated because true vascular is generally apparent without their use.

Aberrant cytological features, necrosis and vascular invasion within the tumour

confined by the capsule point to a diagnosis of "atypical  adenoma".

These have a benign course.

Fine needle aspiration cytology may implant follicular epithelium into the capsule

giving a pseudomalignant appearance.

Over diagnosis of follicular neoplasms is a risk if the features of hyperplastic nodules

in multinodular goiter are overlooked.

Further reading

Prognostic factors in papillary and follicular thyroid carcinoma: their implications for cancer staging.  

Follicular thyroid carcinoma

Follicular thyroid carcinoma: the role of histology and staging systems in predicting survival. 

Follicular thyroid carcinoma: histology and prognosis.

A clinicopathologic study of minimally invasive follicular carcinoma of the thyroid gland with a review of the English literature.

Prognosis and prognostic factors of follicular carcinoma in Japan: importance of postoperative pathological examination.



Dr Sampurna Roy  MD

Consultant  Histopathologist (Kolkata - India)  ;  Dermpath-India  ;   Soft Tissue Tumour Online ; Cardiac Path Online ;

Infectious Disease Online ;  Paraganglioma-Online Mesothelioma-Online ; Pathology Quiz Online ;

GI Path Online ; Pulmonary Pathology Online  ; Lung Tumour Online ; Endocrine Pathology Online ;

Ear Pathology Online ;   Eye Pathology Online ; Paediatric Pathology Online ;

E-book - History of Medicine ; Microscope - Seeing the Unseen





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