Thyroid gland
Competency Assessment
6. Neoplasm

Author: Ricardo R. Lastra, M.D., Michelle R. Pramick, M.D., Zubair W. Baloch, M.D. (see Authors page)

Revised: 20 January 2017, last major update November 2013

Copyright: (c) 2013-2017, PathologyOutlines.com, Inc.

Cite this page: Neoplasm. PathologyOutlines.com website. http://pathologyoutlines.com/topic/thyroidcompneoplasm.html. Accessed July 26th, 2017.
Follicular Neoplasms
Medical knowledge
  1. Recognize clinical and radiologic features suggestive of a follicular neoplasm
  2. Understand the histologic criteria utilized to diagnose follicular adenomas and minimally invasive follicular carcinomas in surgical pathology material and their implication in cytologic evaluation of thyroid FNAs
    • Usually single
    • Encapsulation
    • Presence or absence of capsular and / or vascular invasion
  3. Understand the histologic criteria utilized to diagnose widely invasive follicular carcinoma
  4. Recognize the architectural and cytologic criteria for diagnosing follicular neoplasms
    • Hypercellular specimen
    • Altered architectural pattern
      • Microfollicle formation - most common
      • Macrofollicle formation
      • Solid pattern
      • Significant cell crowding
      • Decreased amount of colloid in background
    • Classic cytologic characteristics
      • Minimal to mild nuclear atypia
      • Nuclear hyperchromasia
      • Inconspicuous nucleoli
  5. Recognize that large follicular neoplasms may undergo cystic degeneration

Practice based learning
  1. Understand the clinical and surgical implication of diagnosing follicular neoplasm in a thyroid FNA specimen
  2. Understand that differentiation of a follicular adenoma from a follicular carcinoma cannot be made in thyroid FNA specimens
  3. Recognize that cases exhibiting nuclear features of papillary thyroid carcinoma are excluded from this category
  4. Recognize widely invasive follicular carcinoma as an aggressive neoplasm with a clinical presentation that differs from that in follicular adenoma and minimally invasive follicular carcinoma
  5. Differentiate follicular neoplasms with cystic degeneration from nodular goiter
  6. Recognize cases in which repeat FNA might help clarify the nature of the lesion
    • Hypocellular lesion with microfollicular pattern - "Atypia of Undetermined Significance"
  7. Recognize mimics of follicular neoplasms
    • Accidental aspiration of parathyroid gland


Images hosted on other servers:

Cytology images:

FNA: follicular neoplasm; Excision: follicular adenoma

Solid cellular nodule, microfollicular lesion

Cells with round nuclei arranged in acini, microfollicular lesion

Cells with round
nuclei in acini and
monolayered sheet,
microfollicular lesion

Oncocytic Follicular Neoplasm
Medical knowledge
  1. Understand the histologic criteria utilized to diagnose Hürthle cell adenomas and Hürthle cell carcinomas in surgical pathology material and their implication in cytologic evaluation of thyroid FNAs
    • Exclusively (or almost exclusively) composed of Hürthle cells
    • Usually single
    • Encapsulation
    • Presence or absence of capsular and / or vascular invasion
  2. Recognize the altered architectural pattern characteristic of oncocytic follicular neoplasms
    • Predominantly single cells
    • Syncytial-like sheets
    • Decreased colloid
  3. Recognize the cytologic characteristics of Hürthle cells
    • Finely granular cytoplasm
    • Large and round central nuclei
    • Prominent nucleoli
  4. Recognize the absence of lymphocytic or plasma cell infiltrate in the specimen

Practiced based learning
  1. Recognize the significance of differentiating oncocytic follicular neoplasms from follicular neoplasms NOS
    • Significantly different histology
    • Potentially different molecular alterations
  2. Understand the clinical and surgical implication of diagnosing oncocytic follicular neoplasm in a thyroid FNA specimen
  3. Understand that differentiation of an oncocytic follicular adenoma from a Hürthle cell carcinoma cannot be made in thyroid FNA specimens
  4. Recognize that cases exhibiting nuclear features of papillary thyroid carcinoma are excluded from this category
  5. Recognize prominent Hürthle cell metaplasia in nodular goiter and chronic lymphocytic thyroiditis as a potential mimic of oncocytic follicular neoplasm
  6. Recognize cases in which repeat FNA might help clarify the nature of the lesion
    • Hypocellular lesion with exclusively oncocytic follicular cells - "Atypia of Undetermined Significance"
  7. Recognize mimics of oncocytic follicular neoplasms
    • Accidental aspiration of parathyroid gland with oncocytic change
    • Medullary thyroid carcinoma with abundant granular cytoplasm


Images hosted on other servers:

Cytology images:

Hürthle cells (pap)

Hürthle cells (Diff-Quik)

Hürthle cell adenoma (pap)

Hürthle cell adenoma (Diff-Quik)

Other
Medical knowledge
  1. Recognize architectural and cytologic criteria of distinct but less common follicular neoplasms
    • Hyalinizing trabecular adenoma
    • Clear cell adenoma

Practice based learning
  1. Recognize characteristic cytologic features of hyalinizing trabecular adenoma as a major mimic of papillary thyroid carcinoma and medullary thyroid carcinoma
  2. Understand that clear cell change can be present in all major variants of thyroid neoplasms and is not unique to follicular neoplasms
  3. Understand that thyroid lesions with clear cell change can represent metastatic disease from other primary organs
    • Metastatic renal cell clear cell carcinoma


Images hosted on PathOut server:

Cytology images:

Metastatic renal cell carcinoma to thyroid gland, contributed by Dr. Mark R. Wick



Images hosted on other servers:

Cytology images, hyalinizing trabecular neoplasm:

Acellular hyaline material within tumor cell cluster

Elongated tumor with acellular stroma

Nuclear overlapping and intranuclear inclusions



Cytology images, metastatic renal cell carcinoma to thyroid gland:

Metastatic renal cell carcinoma, clear cell type

Bloody background with clusters of atypical cells nuclei are somewhat pleomorphic with prominent nucleoli