DIFFERENTIATED THYROID CARCINOMA

ANGEL DAS

Endocrine gland – lower part of neckExtend – oblique line of thyroid to 5th or 6th tracheal ringsConsists – right & left lobes joined by isthmusCapsules – true & false

ANATOMY

Blood supply Arterial Supply• Superior thyroid arteries• inferior thyroid arteries. Venous Drainage• Superior• middle • inferior thyroid veins.

PHYSIO LOGY-

The primary ph ysiologic role is the production of thyroid h ormone, which plays an im portant role in metabolic homeostasis.

A secondary role is the production of calcitonin, a horm on e involved in calcium hom eostasis.

The follicular cells of th e thyroid gland synthesize and secrete thyroglobulin(Tg) and thyroid hormone in two biologically active form s,

thyroxine (3,5,3′,5′ iodothyronine or T4) and

triiodothyronine (3,5,3′ iodothyronine or T3).

T4 is considered the storage and transport form of the hormone and T3 is considered the metabolically active form.

CLASSIFICATION OF THYROID TUMORSBENIGN MALIGNA

NTFollicular adenoma

primary secondary

Parafollicular cells

Lymphoid cells

-Metastatic-Local infiltration-

follicular-papillary

-anaplastic

-medullary

-lymphoma

Differentiated

Undifferentiated

DIFFERENTIATED THYROID CARCINOMA

Tumors derived from follicular cells9o% of all thyroid malignanciesMost common presentation – Solitary thyroid nodule

Papillary CarcinomaAetiopathogenesisRadiation therapy- in childhood for adenoids,

thymus enlargement,

hemangiomasHashimoto thyroiditis

Familial

Genetic - chromosomal rearrangement fusion protein RET/PTC Mutational activation of BRAF gene Activation of

MAP kinase pathway

Altered gene expression

Uncontrolled growth

80% of thyroid malignancy

Commoner in females and younger age group

Lymphatic spread is common

Multiple foci in same lobe

GrossFeatures

Papillary projections

Orphan Annie eye nuclei

Psammoma bodies

Histology

Clinical features …..

o Compression features are less common

o Metastasis to cervical lymph node

o Microcarcinoma < 1cm

o Young females (20-40 years)

o soft / hard / firm ,solitary / multifocal swelling

Follicular carcinomaAetiopathogenesisDeficiency of dietary iodinePre existing multinodular goitreGenetic factors - Fusion of PAX8 gene to

PPAR gamma

10% of thyroid carcinoma

Common in women & older age group(40-60yrs)

Distant metastasis through blood into bones,lungs & liver

Bone secondaries – vascular, warm, pulsatile commonly in skull, long bones & ribs

Most common presenting feature – solitary thyroid nodule

Morphology

Minimally invasive – grossly

encapsulated

Widely invasive – may be

unencapsulated

• Capsular & vascular invasion

CLINICAL FEATURES . . . solitary thyroid nodule - firm/ hard

Stridor – tracheal compression / infiltration

Dyspnoea, hemoptysis, chest pain – lung secondaries

Hoarseness of voice – recurrent laryngeal nerve

involvement

F : M = 3: 1

Hurthle cell Carcinoma -more aggressive variant of follicular ca. -contain oxyphil cells

-They secrete thyroglobulin

-metastasize to local lymph nodes

-potentially malignant.

InvestigationsSerum TSH - Papillary Carcinoma

Thyroid imaging• Radionuclide Imaging – using radiolabelled iodine 123I / Technetium

FNAC -with /without ultrasound guidance -inconclusive in follicular carcinoma

Ultrasound -evaluation of thyroid nodule -provide information about size & multicentricity

CT/MRI -excellent image of thyroid gland & nodes -relationship with airway & vascular structures

PET scan -clinically occult thyroid carcinoma

Chest & Thoracic inlet X ray - confirm clinically important degrees of tracheal deviation - Pulmonary metastasis detected

Skull X ray

Lytic lesions

TNM StagingNODES N0 – No regional node metastasis N1a – level VI N1b – any other levels

METASTASIS M0 – No metastasis M1 – metastases present

Stage Under 45 yrs Over 45 yrsI Any T, any N, M0 T1 , N0, M0II Any T, Any N, M1 T2, N0, M0III T3/T1, T2 & N1a M0IVA T4/T1,T2,T3T4a&

N1b, M0IVB T4b, Any N, M0IVC Any T, Any N, M1

Tx-ThyroidectomyRose position

Kocher’s incision

Total thyroidectomy recommendations- If the papillary thyroid carcinoma is >1 cm Follicular adenoma > 4cm Multifocal disease Regional or distant metastases are present, The patient has a personal history of radiation therapy

to the head and neck The patient has first-degree family history of DTC.

Older age (>45 years) – near-total or total thyroidectomy - tumors <1–1.5 cm

Surgical Treatment

Hemithyroidectomy small (<1 cm), low-risk, unifocal, absence of

• prior head and neck irradiation• radiologically or clinically involved

cervical nodal metastases.

Lymph Node Dissection

Therapeutic central-compartment (level VI) neck dissection - clinically involved central or lateral neck lymph nodes

Prophylactic central-compartment neck dissection (ipsilateral or bilateral) – advanced papillary thyroid carcinoma (T3 or T4).

Not needed small (T1 or T2), noninvasive, clinically node-negative PTCs and most follicular cancer.

Modified Radical Neck Dissection – metastasis to lateral cervical lymph nodes

Post-Operative Management of Differentiated Thyroid Carcinoma

Radioiodine therapy - reduces recurrence & metastasisThyroxine- 0.1-0.2mg to suppress endogenous TSH productionThyroglobulin -

Complications Hemorrhage

Recurrent laryngeal nerve palsy

Hypoparathyroidism

Hypothyroidism

Injury to external laryngeal nerve

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