Medical Archive

Goiter and nodular thyroid disease

Diffuse nontoxic (simple goiter)

Etiology and pathogenesis

Clinical manifestations and diagnosis

Treatment

T4 suppression

Nontoxic multinodular goiter

Etiology and pathogenesis

Clinical manifestations

Diagnosis

Treatment

Due to relative iodine deficiency ??? ??

Toxic multinodular goiter

D/t persistent TSH-stimulation.
Age >60, often have a history of iodine deficiency.

Treatment

Regions become TSH-independent leading to T4 release and hyperthyroidism (TSH receptor mutation in 60%)
????? or BB ? RAI/surgery

Focal patches of hyperfunctioning follicular cells distended with colloid

Hyperfunctioning solitary nodule

D/t gain of function mutation in the TSH receptor gene that causes autonomous functioning of the TSH receptor.

Treatment

RAI ablation/surgery

Benign lesions

Follicular adenoma

Benign proliferation of follicles surrounded by a fibrous capsule.
Without capsular or vascular invasion.
Usually nonfunctional; less commonly, may secrete thyroid hormone

Histology: sheets of uniform cells forming small follicles.

Thyroid cancer

Treatment: <Sabiston>

Malignancy ???? ? ?	Medullary ca., MEN II FHx ??? ??? ?? ~20?, 45?~, ?? ??, ??, ?? irregular, >4cm Calcitonin, Tg ?? ?? Cold nodule
Thyroglosal duct cyst	m/c congenital midline mass Asymptomatic mass below the hyoid boin + local infection, fistula, etc. 1%? malignancy? ? ?? ? ?? ??? ???? hyoid bone? ????? ??? high ligation ?????.
Ectopic thyroid	90%? lingual, 30%? thyroid Sx? tongue base?? obstruction (?? ?? ??? ? ????) ???? ??? ??.

Classification

Pathogenesis and genetic basis

Well-differentiated thyroid cancer

Cytology	DTC (differentiated thyroid cancer, PTC+FTC)
??	????: ? ???? risk factor ??? ??? ??? ?? ??. ??, intermediate: ???? ????: 4m ??, ???? sono ? ??? ? ??? ??
?	??? ??? ? ?? or N+ or M+ or >4cm ? ??? ? ??? ?? ??? ? ??? ?? ??. 1cm ????? ?? ??. Minimally invasive?? ????? ??!

Papillary

70-80%
?risk with RET/PTC rearrangements and BRAF mutations, childhood irradiation.
??? ?? ?? (?? ?? ??? ??? ??) LN ?? ??. ?????? ?? 

• Histology
  • Psammoma body, Orphan annie’s eye, multinucleated giant cells (not specific)
  • (a) Tall cell variant 
    • In older individuals and carrier a relatively worse prognosis. Ddx with Graves.
  • (b) Columnar cell variant

?? ??: 40???, ?? ??, 4cm ??

Follicular

5-10%
Iodine ????? ??. Associated with RAS mutation and PAX8-PPAR-? translocations.
???? ?? (bone, lung, CNS) Invades thyroid capsule and vasculature (unlike follicular adenoma)

DDx from follicular adenoma

• Invasion through the capsule helps distinguish follicular carcinoma from follicular adenoma.
• Entire capsule must be examined microscopically.
• FNA only examines cells and not the capsule; hence, a distinction between follicular adenoma and follicular carcinoma cannot be made by FNA.
• FNA?? adenoma? ??? ???? ?? ?? ??

Variant – Hürthle cell carcinoma

• Hürthle cell: follicular cell with an abundance of finely granular cytoplasm.
• ?? ?? ?? ?? ?? ??? ± LND

Treatment

• Surgery
  • 1cm ??: lobectomy + isthmectomy
  • 1-2cm & 40? ??: total thyroidectomy
  • 2cm ??: total thyroidectomy
  • LN(+): Modified radical neck dissection
  • ?? ??
    • 1cm ??? ?? ?? ???? ???? ???.
    • ??? ?? Ix: ??? ?? ???? ??, ????, head & neck RTx? Hx., 45? ??.
• Postop treatment
  • TSH suppression therapy
  • Iodine (131 I) therapy – ??? ??? L/M (+)? ??.
• ??, ?? ? ?? ??
  • ?? 6?? ? initial whole body 131 I scan
  • Negative finding
    • ?? 1? ? ??
    • ?? ? negative: T4 suppression therapy ??? 6-12???? TSH, Tg, anti-Tg Ab titer ??.
  • Positive finding
    • Therapeutic 131 I
  • Tg? ?? low risk ??? ?? ? ? 1? ??? routine?? whole body scan ?? ?? Tg? ?? ??.

Anaplastic and other forms of thyroid cancer

Anaplastic thyroid cancer

3?? ? ??? ??: ????, ????, ????
Histology: pleomorphic giant cell nests with occasional multinucleated cells.

Thyroid lymphoma

Medullary thyroid carcinoma

• Epidemiology and pathophysiology
  • 5%. Parafollicular C cell origin.
  • MEN 2A, 2B, familial MTC
  • Calcitonin often deposits within the tumor as amyloid.
• Clinical features
  • Asymptomatic – m/c
  • Diarrhea and flushing – minority
• Lab findings
  • Serum calcitonin is usually normal, possibly d/t downregulation of calcitonin receptors.

Diagnosis

Confirmed with FNA
Histology: sheets of malignant cells in an amyloid stroma (Congo red-positive)

Management

• Total thyroidectomy + Central LND
  • LND ??? ??: LN ??? ???? ??? ??? ??? ???, ???? ??? ??? ??.
  • ????? ????? calcitonin? ???? ??
  • ¹³¹I ? ?? ??.
  • RET mutation? ?? ?? prophylactic thyroidectomy? ??.
• Postoperative thyroid replacement therapy
• Follow up
  • Calcitonin – correlate with the risk of metastasis, recurrence
  • CEA – correlate with disease progression

Approach to the patient

Thyroid nodule

DIAGNOSTIC CATEGORY	RISK OF MALIGNANCY
I. Nondiagnostic or unsatisfactory	1–5%
II. Benign	2–4%
III. Atypia or follicular lesion  of unknown significance (AUS/FLUS)	5–15%
IV. Follicular neoplasm	15–30%
V. Suspicious for malignancy	60–75%
VI. Malignant	97–100%

Follicular carcinoma? FNA? ??? ? ????, follicular neoplasm? ?? ?? carcinoma ??? ???? ?? diagnostic hemithyroidectomy? ????.