Thyroid
Background
Thyroid lesions may be investigated by fine needle aspiration followed by partial or total thyroidectomies to remove benign tumours such as follicular adenomas or malignant neoplasms such as papillary, follicular, medullary and anaplastic carcinomas.1-3 Expertise in endocrine pathology is required to distinguish pseudomalignant conditions that mimic thyroid cancers.4,5
Enlarged thyroid gland (goitre) due to hyperplastic conditions such as such nodular hyperplasia and Grave’s disease may also be treated by surgery.6 Thyroidectomy may be required to treat compression symptoms that have not been resolved by medical treatment. Multinodular goitre and Hashimoto’s thyroiditis may also be treated by surgery for cosmetic reasons or to investigate a suspicious nodule within the thyroid gland.5,7
Parathyroid glands and lymph nodes may be included in resection specimens. Thyroids may be resected prophylactically where there is a high risk of familial medullary carcinoma on genetic testing.8
Record the patient identifying information and specimen description as designated on the container.
Record the clinical notes including all relevant previous history and treatment. Note the receipt of fresh tissue, requests for special studies and any intraoperative consultant performed.
Inspect the specimen and dictate a macroscopic description.
- No
- Non-routine fixation (not formalin), describe.
- Yes
- Special studies required, describe. Describe and ensure samples are taken prior to fixation.
- Not performed
- Performed, describe type and result
- Frozen section
- Imprints/cytology
- Other, describe
External Inspection
Orientate and identify the anatomical features of the specimen.
Orientate the thyroid by identifying the isthmus which is located inferiorly to the two lateral lobes which have concave surfaces posteriorly. The lobes tend to taper superiorly.1,9
Record additional orientation or designation provided by operating clinician:
- Absent
- Present
- Method of designation (e.g. suture, incision)
- Featured denoted
Photograph the intact specimen if required.
Describe the following features of the specimen:
Procedure
Describe as stated by the clinician.
Orientate and identify the anatomical features of the specimen.
- Partial lobectomy
- Lobectomy
- Lobectomy with isthmusectomy (hemithyroidectomy)
- Subtotal thyroidectomy
- Total thyroidectomy
- Completion thyroidectomy
- Neck dissection See specific protocol
- Other, describe
Anatomical components included (more than one may apply) and specimen dimensions (mm)
Describe and measure the components present.
Thyroid
- Right lobe, in three dimensions
- Left lobe, in three dimensions
- Isthmus, in three dimensions
Parathyroid glands
- Absent (or not identified)
- Present, number. See specific parathyroid protocol for more detail.
- Other, describe
Specimen weight (g)
Record the weight of the entire specimen.
Specimen laterality (if applicable)
Specimen integrity
- Intact
- Disrupted, describe
Thyroid capsule
Describe the capsular surface and measure the maximum dimension (mm) of each area of abnormality.
- Adhesions
- Fibrotic
- Purulent
- Nodular
- Tumour present
Dissection
Paint the entire throid gland surgical margins with ink and record the colours applied.
Serially section the specimen transversely from superior to inferior at 3-4mm intervals. One suggested method is to retain orientation is to leave slices attached at lower edge rather than completely cutting through the specimen.1
After opening the specimen may require longer fixation in larger quantity of formalin.
Photograph the dissected specimen if required. An annotated photograph may be useful to facilitate block labelling.
Internal Inspection
Describe the cut surface appearance including the following items:
Focal lesions
Multiple lesions
- No
- Yes
- Number; if more than one tumour, designate and describe each tumour separately
Tumour location1
- Right lobe
- Superior
- Central
- Inferior
- Left lobe
- Superior
- Central
- Inferior
- Isthmus
Lesion size (mm)
Tumour description
- Solid or cystic
- Colour
- Consistency8
Borders1
- Encapsulated
- Infiltrating
Distance of tumour to margins (mm)
- Distance of tumour to nearest excision margin1
Non-lesional tissue appearance
- Colour
- Consistency
- Contour
- Calcifications
Retrieved from resection specimen
- Describe site(s)
- Number retrieved
Separately submitted
- For each container, record specimen number and designation
- Collective size of tissue in three dimensions (mm)
- Number of grossly identified lymph nodes submitted
- Maximum diameter of each (mm)
Others
- Describe any adjacent tissue such as fat, skeletal muscle, and parathyroid glands, and note any extension of tumor into these tissues.9
Processing
Dissect the specimen further and submit sections for processing according to the illustrations provided.
There is no single universal method for sampling thyroid neoplasms. It is recommended that tissue is widely sampled between the nodule and adjacent capsule and thyroid tissue. Areas of thickened capsule, fleshy cut surface, pale or very solid areas are considered suspicious.1
Submit representative sections of:
- Each lobe, at least three sections
- Isthmus, at least one section
- Multinodular thyroid gland
- Each nodule, at least one section including rim and adjacent normal gland
- Additional sections to be submitted from nodules with thick capsules or heterogeneous appearance.9
- Submit sections from all foci of white-cream tissue (as they may represent cancer)1
These thyroids are often small and any tumours present may be difficult to detect macroscopically. It is therefore common practice to submit all thyroid tissue including the isthmus for processing.2 Immunohistochemistry for Calcitonin will assist in identifying medullary carcinoma and the presence of C cell hyperplasia.2
- < 30mm in maximum dimension, submit the entire lesion1
- >30mm in maximum dimension, alternate serial sections2 or one section per 10mm of lesion1
- Regardless of the size of the lesion, submit the entire capsule demonstrating relationship with adjacent tissue
- Non-lesional tissue, two further blocks from in each lobe and one from the isthmus
For suspected invasive cancer i.e. papillary, medullary or undifferentiated carcinoma1
- <20mm, submit all tumour tissue
- >20mm, at least one section per 10mm of tumour
- Non-lesional tissue - three further sections from each lobe and one from the isthmus
It may be considered necessary to submit all tissue from suspected medullary carcinomas.1 Other rare inflammatory conditions are occasionally encountered that may require more extensive sampling of the thyroid.
Submit all foci of white-cream tissue,1 if present. Alternatively submit all tissue for processing.2
Submit all lymph nodes and parathyroid glands, if present.1
Record details of each cassette.
An illustrated block key similar to those provided may be useful.
Block allocation keys
|
Cassette id
|
Site
|
No. of pieces
|
|
A-C
|
Right lobe
|
|
|
D-F
|
Left lobe
|
|
|
G
|
Isthmus
|
|
|
H-J
|
Nodules, if applicable, including rim and normal gland
|
|
|
K-L
|
White-cream foci, if applicable
|
|
|
M+
|
Lymph nodes, if applicable
|
|
|
|
Parathyroids, if applicable
|
|
|
Cassette id
|
Site
|
No. of pieces
|
|
A-C
|
Lesional tissue, all sections or representative sections (see above)
|
|
|
D-E
|
Lesion demonstrating relationship with margins
|
|
|
F-G
|
Entire capsule demonstrating relationship with adjacent tissue
|
|
|
H-I
|
Non-lesional tissue, representative sections
|
|
|
J+
|
Lymph nodes, if applicable
|
|
|
|
Parathyroids, if applicable
|
|
|
Cassette id
|
Site
|
No. of pieces
|
|
A-C
|
Lesional tissue, all sections or representative sections (see above)
|
|
|
D-E
|
Lesion demonstrating relationship with margins
|
|
|
F-H
|
Non-lesional tissue, representative sections one from each lobe and the isthmus
|
|
|
I+
|
Lymph nodes, if applicable
|
|
|
|
Parathyroids, if applicable
|
|
|
Cassette id
|
Site
|
No. of pieces
|
|
A-H
|
White-cream foci or all sections, as applicable
|
|
|
I+
|
Lymph nodes, if applicable
|
|
|
|
Parathyroids, if applicable
|
|
Acknowledgements
Prof Alfred Lam, Prof Jane Dahlstrom and A/Prof Kais Kasem for their contribution in reviewing and editing this protocol.
References
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-
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Rosai J, Carcangiu ML and DeLellis RA. Tumors of the Thyroid Gland. Atlas of tumor pathology. Armed Forces Institute of Pathology, Washington DC, Third series, Fascicle 5, 1992.
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Al-Sam S, Lakhani SR and Davies JD (eds). A Practical Atlas of Pseudomalignancy: Benign Lesions Mimicking Malignancy, Hodder Arnold, London, 1998.
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Lloyd RV, Douglas BR and Young WF (eds). Endocrine Diseases: AFIP Atlas of Nontumor Pathology, American Registry of Pathology and Armed Forces Institute of Pathology, Washington, 2002.
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Lester, S. C. Manual of Surgical Pathology E-Book, Elsevier Health Sciences, 2010.