investigations thyroid carcinoma

INVESTIGATIONS

By,NEHA HUSSAINRoll no:30

WHY INVESTIGATE?• To establish a definitive diagnosis in cases

where clinical examination gives indistinguishable results.

• To differentiate between malignant and benign tumors

• Treatment(conservative or surgical line of management)

Laboratory Evaluation• Serum TSH, T3 and T4 levels:If a 1 cm or larger nodule is identified.

Low TSH(<0.5µIU/ml) Denotes subclinical hyperthyroidism; radioisotope

scan is indicated. Correlates with a lower likelihood of malignancy.

High TSH:Suggests hypothyroidism(Hashimoto’s thyroiditis)

• Serum calcitonin levels: High in Medullary carcinoma.

Male: >13.8 ng/L Female: >6.4 ng/L

• Detection of Thyroid antibodies in patients with toxic features(anti-thyroglobulin antibodies).

Thyroid ImagingUltrasound:All nonthyrotoxic nodules should be evaluated. Determines the location and

characteristics(cystic versus solid) Useful in patients who are being managed

conservatively to detect increased volume of a suspicious lesion.

Detect Lymph nodes.

Disadvantages:Limited ability to predict the diagnosis of solid nodules accurately.FINDINGS: Microcalcifications Hypervascularity Infiltrative margins Being hypo-echoic compared to the surrounding

parenchyma Having a shape that is taller than its width on

transverse view

The size of the nodule on ultrasound determines the need for further evaluation.A nodule <1 cm in size is not further evaluated unless it is associated with:

suspicious characteristics or

suspicious lymphadenopathy

Family history of papillary carcinoma of thyroid

Prior personal history of thyroid cancer

Radiation exposure

PET positive lesions

RADIOISOTOPE SCANNING:

Assessment of thyroid function.

Dominant thyroid nodule larger than 1cm in size with low TSH using technetium-99m pertechnetate or 123I

99mTc is trapped by follicular cells and its rapid absorption allows quick evaluation of increased uptake or cold nodule

123I and 131I iodine scintigraphy is also used to evaluate the functional status of the gland.

131I is a good choice for imaging thyroid carcinoma and is the screening modality of choice for the evaluation of distant metastasis.

Categorized as Hot, Warm or Cold nodule Malignancy has known to occur in 15-20% of

cold nodules and 5-9% of hot nodules.

FINE NEEDLE ASPIRATION BIOPSY • KEY MODALITY for evaluation(86% sensitivity)• ‘Fine or thin’ gauge needle(23 to 27 gauge)

used.

• All dominant non functioning thyroid nodules that are 1 cm or larger should be evaluated.

Results of FNA biopsy can be grouped into:Malignant, indeterminate or suspicious, benign and non-diagnostic.

Malignant changes:Papillary carcinoma:Cellular changes include: Intranuclear grooving, Ground glass cytoplasmic inclusions(‘Orphan

Annie eyes’) Presence of Psammoma bodies.

Medullary carcinoma: Typically, aspirates are hypercellular,

composed of large, poorly cohesive cells,

predominantly spindle‑shaped.

Amyloid is often, but not invariably, present, and there is no colloid

Follicular carcinoma:Demonstration of capsular or vascular invasion by follicular cells not by cellular cytology alone but on complete histological examination of the resected specimen.

Indeterminate: Repeat aspiration,resection,or close

conservative follow-up of the nodule

Benign Lesions: The tissue immediately adjacent to or

contained within another part of the nodule may harbour malignant cells(false negetive rate:1-6%)

Monitor with ultrasound.

In cases of non-diagnostic cytology, repeat FNA under ultrasound guidance

Lesions in which FNA is found to be persistently non-diagnostic is associated with a high risk of malignancy and must be followed up closely or excised.

FNA can also be done for lesions that appear cystic on ultrasound: occasionally papillary carcinoma may manifest as a cyst.

COMPUTED TOMOGRAPHY AND MAGNETIC RESONANCE IMAGING

Both are equally sensitive and specific for evaluating local extension in more advanced stages of thyroid cancer.

It is appropriate for a suspicious mass with palpable cervical lymph nodes

CT or MRI is advisable in pre-operative planning for large thyroid masses that show tracheal deviation suggestive of a substernal goiter on chest radiographs

Thyroid nodule

High TSHLow TSH

History and physical exam

Serum TSH

Radioisotope scan

Ultrasound

HOT Nodule COLD Nodule

131I or Surgery

>1cm or suspicious <1cm

Follow-upCyst aspirate Solid

FNANon-

Diagnostic

Malignant

Suspect mal’cy

Indeterminate Hurthle

Indeterminate follicular

Benign

Repeat

SURGERY

123I scan

Follow-Up

Cold nod.

Ultrasound

Malignant

SURGERY