Thyroid & parathyroid

Papillary thyroid carcinoma

Other subtypes

Invasive EFVPTC



Last author update: 23 March 2022
Last staff update: 4 May 2023

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PubMed Search: Invasive EFVPTC

Rachel Jug, M.B.B.Ch., B.A.O.
Xiaoyin
Page views in 2022: 3,468
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Cite this page: Jug R, Jiang X. Invasive EFVPTC. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/thyroidinvasiveEFVPTC.html. Accessed September 22nd, 2023.
Definition / general
  • Prognostically distinct entity from counterpart NIFTP (noninvasive follicular thyroid neoplasm with papillary-like nuclear features)
Essential features
  • Same nuclear features and follicular architecture as NIFTP but with vascular or tumor capsule invasion present
Terminology
  • Encapsulated follicular variant of papillary thyroid carcinoma with invasion
ICD coding
  • ICD-10: C73 - malignant neoplasm of thyroid gland
Epidemiology
Sites
  • Thyroid
Pathophysiology
Etiology
Clinical features
  • May be found incidentally on imaging or present as a visible or palpable tumor in the thyroid
Diagnosis
Laboratory
  • Follicular variants of papillary thyroid carcinoma may be associated with elevated serum thyroglobulin (Thyroid 2016;26:872)
Radiology description
  • Ultrasound features include solid composition, smooth margins, parallel orientation, round to oval shape and presence of a halo (hypoechoic rim surrounding thyroid nodule) (Thyroid 2017;27:1177)
Prognostic factors
  • Good prognosis
  • Based on an international, multidisciplinary, retrospective study in which 101 participants had invasive EFVPTC, 12 patients experienced an adverse event (including 5 patients developing distant metastases and 2 patients dying of the disease) by a median follow up time of 13 years (JAMA Oncol 2016;2:1023)
Case reports
  • 35 year old man with invasive encapsulated follicular variant of papillary thyroid carcinoma metastatic to lung at presentation (Mod Pathol 2010;23:1191)
  • 43 year old patient with encapsulated follicular variant of papillary thyroid carcinoma showing capsular and vascular invasion on histology (ARS Medica Tomitana 2018;24:15)
  • 3 cases of encapsulated follicular variant of papillary thyroid carcinoma with focal vascular invasion and bone metastases (Mod Pathol 2000;13:861)
Treatment
  • Hemithyroidectomy with or without isthmusectomy, near total thyroidectomy or total thyroidectomy
  • Depending on size and stage, may consider lymph node dissection and radioactive iodine ablation for subtotal thyroidectomies (Thyroid 2009;19:1167)
Gross description
Frozen section description
  • Frozen sections generally not recommended on primary thyroid tumors, particularly ones with preoperative cytology diagnoses of follicular patterned lesions, as diagnosis of these requires evaluation of the entire capsule
Microscopic (histologic) description
  • Tumor invades capsule or extends into adjacent thyroid tissue or has evidence of lymphovascular invasion
  • Nuclear features of papillary thyroid carcinoma:
    • Size and shape: nuclear enlargement / overlapping / crowding, elongation
    • Nuclear membrane irregularities: irregular contours, grooves, pseudoinclusions
    • Chromatin characteristics: clearing with margination / glassy nuclei
  • Follicular growth pattern may be microfollicular, normofollicular or macrofollicular with abundant colloid
Microscopic (histologic) images

Contributed by Andrey Bychkov, M.D., Ph.D. and Rachel Jug, M.B.B.Ch., B.A.O.
Vesicular nuclei with irregular membranes

Vesicular nuclei with irregular membranes

Evident major and minor diagnostic features

Evident major and minor diagnostic features

Dark colloid with frequent scalloping and clefting

Dark colloid with frequent scalloping and clefting

Free floating of small tumor fragment in vascular lumen

Free floating of small tumor fragment in vascular lumen

Small piece of tumor floats in vascular lumen

Small piece of tumor floats in vascular lumen


Capsular invastion and extrathyroidal extension

Capsular invasion and extrathyroidal extension

Tumor plug is associated with thrombus

Tumor plug is associated with thrombus

Overlapping, elongation and a single mitotic figure

Overlapping, elongation and a single mitotic figure

Irregular nuclear contours, grooves, pseudoinclusions

Irregular nuclear contours, grooves, pseudoinclusions

Clear chromatin with margination

Clear chromatin with margination

Cytology description
  • FNA samples are usually hypercellular with neoplastic cells containing nuclear features of papillary thyroid carcinoma arranged in microfollicles
  • Nuclear features are more subtle than conventional papillary thyroid carcinoma (Endocr Pathol 2014;25:257)
  • Colloid may be present
  • Cannot distinguish invasive EFVPTC from NIFTP on cytology, as cannot evaluate capsule on FNA
Cytology images

Contributed by Xiaoyin "Sara" Jiang, M.D.
Microfollicles and nuclear enlargement

Microfollicles and nuclear enlargement

Negative stains
Molecular / cytogenetics description
  • Shares molecular features (RAS type mutations) with follicular adenoma, follicular carcinoma (Mod Pathol 2010;23:1191)
  • Follicular variants of papillary thyroid carcinoma more commonly harbor RAS type mutations than classic variant of papillary thyroid carcinoma (more BRAF type mutations); however, invasive EFVPTC is associated with more BRAF type mutations than noninvasive EFVPTC (which is associated with more RAS type mutations) (Cell 2014;159:676, Mod Pathol 2010;23:1191)
Sample pathology report
  • Right lobe, partial thyroidectomy:
    • Invasive encapsulated follicular variant of papillary thyroid carcinoma
Differential diagnosis
Board review style question #1

Which histological feature in the image above separates invasive encapsulated follicular variant of papillary thyroid carcinoma from noninvasive follicular thyroid neoplasm with papillary-like nuclear features?

  1. Capsular invasion
  2. Lymph node metastasis
  3. Microfollicular growth pattern
  4. Mitotic figures
  5. Nuclear enlargement
Board review style answer #1
A. Capsular invasion

Comment Here

Reference: Invasive EFVPTC
Board review style question #2

Which of the following histologic descriptions meets the criteria for capsular invasion?

  1. Bosselation on inner aspect of capsule
  2. Follicles aligned parallel to capsule
  3. Follicles aligned perpendicular to capsule
  4. Tumor bud invading into but not through capsule
  5. Tumor transgresses through and beyond outer contour of capsule
Board review style answer #2
E. Tumor transgresses through and beyond outer contour of capsule

Comment Here

Reference: Invasive EFVPTC
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