encapsulated papillary thyroid carcinoma

Definition: Encapsulated papillary thyroid carcinoma (EPTC) can have a histologic growth pattern similar to the one seen in classical papillary thyroid carcinoma (PTC) or akin to the follicular variant of PTC (FVPTC). E-CPTC resembles classical PTC in its propensity to metastasize to lymph nodes and its vascular/capsular invasive pattern while E-FVPTC behaves more like follicular carcinoma/adenoma group of tumors.

Meticulous search for capsular and vascular invasion can reliably predict the metastatic potential of E-FVPTC but not of E-CPTC. The latter can therefore be treated like unencapsulated classical PTC.

Variants

 NIEFV-PTC / non-invasive encapsulated FV-PTC

• or NIFT-P
• Non-invasive E-FVPTC could be managed like "minimally invasive follicular carcinoma" by lobectomy without RAI therapy.
• Ecapsulated or well-circumscribed
• papillary-like nuclear features
• exclusion criteria :
  • true papillae > 1% (CPTC )
  • psammoma bodies (CPTC )
  • invasive growth (IEFV-PTC )
  • tumor necrosis (PDTC )
  • high-mitotic activité (> 3/10 HPFs) (PDTC )
  • cell morphological characteristics of other variants (other PTC variants)

 IEFV-PTC / invasive encapsulated FV-PTC

• Invasive E-FVPTC seem quite indolent if no distant metastases are found at presentation.

References

 Encapsulated papillary thyroid carcinoma: a clinico-pathologic study of 106 cases with emphasis on its morphologic subtypes (histologic growth pattern).
Rivera M, Tuttle RM, Patel S, Shaha A, Shah JP, Ghossein RA. Thyroid. 2009 Feb;19(2):119-27. doi : 10.1089/thy.2008.0303 PMID: 19191744