investigations thyroid carcinoma
TRANSCRIPT
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