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DEMS: Unit III > Thyroid Nodules: Clinical, Pathologic and Pathophysiologic Correlates > Flashcards

Thyroid Nodules: Clinical, Pathologic and Pathophysiologic Correlates Flashcards

1
Q

Disorders that can lead solitary thyroid nodules

A
  • follicular/hurthle cell adenoma
  • follicular/hurthle cell carcinoma (5-15%)
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2
Q

Characteristics of Hurthle cell adenoma

A
  • Benign neoplasm derived from follicular epithelium
  • Solitary nodule with a well formed capsule that compresses the adjacent non-neoplastic thyroid
  • Microscopically
    • Variable sized follicles lined by follicular cells or Hurthle cells; confined within the capsule
    • Microscopic view of entire capsule is only way to distinguish adenoma from carcinoma
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3
Q

Characteristics of Hurthle cell carcinoma

A
  • Very similar to the adenoma except that it may be minimally invasive or widely invasive
  • Solitary nodule, made of variable sized follicles, lined by follicular or Hurthle cells
  • Again, distinction between adenoma (benign) and carcinoma (malignant) can only be made after a thorough microscopic review of the entire capsule; nuclear atypia or other cytologic features are not helpful in this distinction
  • 50% are caused by PPAR ɣ - PAX 8 rearrangment
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4
Q

Minimally invavsive vs. Widely invasive Hurthle cell carcinoma

A
  • Minimally invasive carcinoma shows capsular or vascular invasion vs adenoma which is confined
  • Widely invasive carcinoma shows extensive invasion, may be even beyond the thyroid capsule into the surrounding soft tissues of the neck
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5
Q

Common cause multiple thyroid nodules

A
  • Papillary Thyroid Carcinoma (PTC):
  • Anaplastic carcinoma
  • Medullary carcinoma
  • Thyroid lyphoma
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6
Q

Microscopic appearance of Papillary thyroid carcinoma

A
  • Variable
  • Classically the architecture shows finger-like structures with fibrovascular cores and epithelial lining → upper right photo
  • Characteristic epithelial cell nuclear features:
  • Fine nuclear chromatin
  • Nuclear clearing = “Orphan Annie”
  • Nuclear grooves
  • Pseudo-inclusions → ground glass nuclei
  • Psammoma bodies, multi-nuc giant cells, and fibrosis may be seen.
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7
Q

Causes of papillary thyroid carcinoma (PTC)

A
  • 20% constitutive act RET by rearrangement
  • 20% Ras point mutation
  • 40% BRAF point mutation
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8
Q

Characteristics of papillary thuroid carcinoma

A
  • Most common type (85%) of thyroid malignancy
  • Any age, often young adults
  • May be multifocal
  • Metastasizes via lymphatics to the neck nodes are not ideal but ok
  • Slow growth, excellent prognosis
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9
Q

Characteristics of Anaplastic carcinoma

A
  • Older age group
  • Extremely aggressive, bulky mass with rapid enlargement, invasive into trachea and soft tissues
  • Composed of highly anaplastic cells exhibiting three distinct morphologic patterns:
    • Spindled
    • Giant cell → photo right
    • Squamoid
  • Poor prognosis, death within a year in most cases
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10
Q

Characterics of medullary carcinoma

A
  • Middle aged or elderly patients, but also children and young adults (MEN IIA|B)
  • Generally high levels of serum calcitonin (no systemic manifestations), hence the MEN link - Endocrine
  • Slow growth, metastasizes to local lymph nodes
  • Prognosis is poor in MEN cases
    *
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11
Q

Microscopic findings/immunostains in medullary carcinoma

A
  • Microscopic:
    • Neuroendocrine C cell nests/ribbons/sheets/cords
    • Amyloid or collagen in supporting stroma
  • Immunostains → neg TG, + Calcitonin, +Chromogranin
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12
Q

Characteristics of thyroid lymphoma

A
  • Primary lymphoma of thyroid is rare but usually arises in the setting of Hashimoto or other autoimmune thyroiditis
  • Common type is B-cell lymphoma
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13
Q

Basic types of thyroid nodules

A
  • Two basic types of thyroid nodules, hot and cold.
  • Cold nodules >> hot nodules.
  • Cold nodules are also the group at risk for being malignant.
  • Hot nodules concentrate radioiodine and are likely benign.
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14
Q

Main tests are helpful to evaluate for thyroid nodule

A
  • Serum thyroid stimulating hormone
  • thyroid scan
  • thyroid ultrasound
  • fine needle aspiration biopsy
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15
Q

Characterstics of serum TSH in evaluation of thyroid nodules

A
  • If the TSH is suppressed, the nodule is likely hot → benign
  • If the TSH is normal or elevated, the nodule is probably cold → malignant
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16
Q

Characterstics of serum thyroid scan in evaluation of thyroid nodules

A
  • Employs radioactive iodine (123I),
  • 123I is concentrated in a hot nodule, but relatively excluded from a cold nodule.
17
Q

Characteristics of thyroid ultrasound (US) in evaluation of thyroid nodules

A
  • Accurately defines number of distinct thyroid nodules as well as location and size
  • Recent studies: certain ultrasound features are more often associated with malignant nodules
  • US characterization of thyroid nodules can target the most suspicious nodules for the most helpful diagnostic tool, the fine needle aspiration biopsy
18
Q

Characteristics of Fine Needle Aspiration Biopsy (FNAB) in evaluation of thyroid nodules

A
  • Way of sampling cells from the thyroid nodule for cytological analysis.
  • Normal sample does not have many cells.
  • Papillary carcinoma has highly cellular aspirate
  • Very reliable way of separating malignant from benign disease.
  • 75- 80% of FNAB will be either clearly benign or clearly malignant and should be treated accordingly
  • Suspicious or indeterminate cytology, comprises up to 15-20% of FNAB results and is the most difficult to manage.
19
Q

Characteristics of suspicious or indertminate cytology on FNAB

A
  • Up to 20% of these nodules will be malignant, but 80% will, of course, be benign.
  • In this group, we consider a thyroid scan → determines if hot or cold nodules
    • If hot, low risk for malignancy, treat accordingly.
    • If cold, integrate clinical information to help direct therapy.
  • low clinical suspicion ==> followed closely with repeat biopsy in 3-6 months.
  • increased clinical suspicion ==> proceed to surgery.
20
Q

Cytologic features of benign FNAB

A

Flat sheets of cells →

Round uniform nuclei, “honey-comb” appearance

21
Q

Cytologic features of papillary cancer on FNAB

A
  • Papillae/sheets of cells + diagnostic nuclear features
  • If architecturally microfollicular, then it is called follicular variant of papillary
22
Q

Cytologic features of follicular neoplasm on FNAB

A

Abundant cells, often in sheets or forming microfollicles

23
Q

Cytologic features of hurthle cell neoplasm on FNAB

A
  • Large cells with abundant cytoplasm
  • Large pleomorphic nuclei
  • Can be seen in groups or as single cells
24
Q

Cytologic features of medullary carcinoma on FNAB

A
  • Small, round to oval parafollicular cells with eccentric nuclei and coarse chromatin,
  • Usually seen as single cells.
  • Stromal amyloid appears as spherical homogeneous material.
  • Immunocytochemistry demonstrates calcitonin.
25
Q

Cytologic features of anaplastic carcinoma on FNAB

A

Large pleomorphic nuclei, malignant-appearing

26
Q

Cytologic features of lymphomas on FNAB

A
  • Cellular aspirate with monotonous population of large lymphocytes.
  • Additional studies (immunostains and flow cytometry to needed to confirm)
27
Q

Risk of malignancy and usual management of non-diagnostic & benign thyroid tumors

A
  • Non-dx:
    • risk = unknown risk
    • tx = Repeat FNA
  • Benign
    • risk = 0-3%
    • tx = Clinical Follow Up
28
Q

Risk of malignancy and usual management of ACUS (indeterminate) thyroid tumors

A
  • risk = 5-15%
  • tx = repeat FNA
29
Q

Risk of malignancy and usual management of suspicious for follicular neoplasm thyroid tumors

A
  • Susp for Follicular Neoplasm:
    • risk = 15-30%
    • tx = lobectomy
30
Q

Risk of malignancy and usual management of suspicous for malignant and malignant thyroid tumors

A
  • suspicious:
    • risk = 60-75%
    • tx = thyroidectomy
  • malignant:
    • risk = 97-99%
    • tx = thyroidectomy

DEMS: Unit III (24 decks)

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