Thyroid and Parathyroid grossing

The grossing of thyroid specimens involves a systematic process where surgical specimens are carefully examined, measured, dissected, and sampled for microscopic evaluation to identify pathology such as nodules, tumors, or inflammation. Common types of thyroid specimens include total thyroidectomy, hemithyroidectomy (lobectomy), subtotal thyroidectomy, and isthmusectomy, each varying based on the extent of tissue removed. The parathyroid glands, small endocrine glands located near the thyroid, regulate calcium levels in the blood and may be examined in cases of hyperparathyroidism or suspected neoplasms. The TNM classification system is a standardized framework used for cancer staging and stands for Tumor size and extent (T), Node involvement (N), and presence of Metastasis (M); it is crucial for determining prognosis and guiding treatment planning in thyroid and other cancers.

1. GROSSING OF THYROID AND PARATHYROID GLAND Dr. Sonia. J Junior Resident Department Of Pathology KMCT Medical College

2. Thyroid is 'butterfly shaped' gland composed of two elongated lobes (right and left) connected by isthmus. Sometimes a conical pyramidal lobe is seen attached to isthmus or one of the lobes, ascending upwards. It is located in front of trachea.

3. Parathyroid glands located on posterior surface of lobes of thyroid gland.

4. Types of Thyroid Specimens • Lobectomy/ Hemithyroidectomy - Removal of one lobe of thyroid along with Isthmus. • Isthmectomy – Removal of isthmus • Near total thyroidectomy – Removal of most of the gland except small portion of posterior part of lower pole of contralateral lobe(solitary nodule) or bilateral lobes. • Total thyroidectomy – Entire thyroid gland is removed( in papillary thyroid carcinoma , multifocal tumor, poorly differentiated thyroid carcinoma , anaplastic and medullary thyroid carcinoma, large multinodular goiter)

5. Completion thyroidectomy : Removal of remaining portion of thyroid gland in post hemithyroidectomy patients, done for removal of residual malignant disease.

6. Steps in Grossing 1. Describe the type of specimen and laterality in case of lobectomy or hemithyroidectomy. 2. Weigh the specimen and record the dimensions of each of the lobes, isthmus, pyramidal lobe, if present and any other mass attached to the gland. 3. Orient the specimen: a. The lobes taper superiorly b. Isthmus is located inferiorly c. Posterior surface is flat to concave .

7. 4. Describe the external surface including : a. Colour b. Appearance (nodular, distorted ) c. Unilateral enlargement, presence of any nodule d. Capsule of thyroid gland (intact or breached) e. Any other structure adherent to gland f. Look for parathyroid gland along the posterior surface and note down if present/absent.

8. 5. Ink the thyroid gland completely and blot dry. 6. Serially section each lobe and isthmus Bisect the specimen by passing the first cut through the greatest dimension. Subsequent parallel cuts should be made at a distance of 5 mm. a ) Either slice the lobes transversely from upper to lower pole (bread loafing) b) Or bisect / slice longitudinally from medial to lateral surface

9. 7. On slicing each lobe and isthmus, note down: a. Consistency of the gland - cystic, firm or hard b. Appearance: Smooth, homogenous or nodular c. Presence of any lesion, nodules or cysts d. Describe the lesions or nodule including : Number, dimensions, shape Colour Appearance (cystic, papillary, nodular). Appearance of tumour can give clue towards type of tumour (e. g. papillary in papillary carcinoma)

10. Consistency (firm, hard or rubbery) Presence of calcifications, necrosis, hemorrhage C ircumscription (encapsulated or invasive) Resemblance to adjacent thyroid parenchyma.

11. e. Distance of tumour from thyroid capsule and inked external surface. f. Presence of extra thyroidal extension. g. Appearance of cut surface of adjacent thyroid gland (colour, nodularity etc.)

12. 8. Sections to be submitted: a)Take representative sections from the suspicious nodules. The sections of nodules should include : Capsule of the nodule Adjacent thyroid Closest thyroid capsule and inked surface of thyroid. Tumour with adjacent extra thyroidal tissue, if present.

13. b) For capsulated solitary nodule, include as much capsule and adjacent thyroid gland as possible. c ) For grossly invasive tumour, submit 3 to 4 sections, including adjacent thyroid as well as closest external inked surface or areas suspicious for extra thyroidal extension.

14. d) If no nodule or lesion is identified in FNAC proven case of papillary carcinoma, entire lobe may need to be submitted. e ) Take representative sections from adjacent thyroid, isthmus as well as the opposite lobe. f ) For grossly uninvolved lobe and multinodular goiter, 3 to 4 sections from one lobe and 2 sections from isthmus should be submitted.

15. g ) Submit lymph nodes attached to the main specimen ,if any, and those received separately. h)For medullary carcinoma and MEN syndrome patients: K nown medullary carcinoma – at least 1 to 2 section from bilateral upper mid poles need to submitted. Patients undergoing prophylactic thyroidectomy for MEN syndrome , submit the entire thyroid.

16. Inflammatory conditions with diffuse enlargement , A,B, C and D : Four bits, 2 from each lobe. E : One bit from the isthmus.

17. Multinodular Goiter A, B, C, D and E : Take representative samples from at least 5 nodules and include the rim and adjacent thyroid. If the nodules are very large sample adequately.

18. Parathyroid gland Types : excision biopsy, incidental in thyroidectomy . Grossing : Measure, weigh, describe color /consistency . Bisect if > 5mm Describe the cut surface: Yellow-brown or gray white, solid/cystic, areas of necrosis, hemorrhage and calcification. Comment on the surrounding thyroid tissue if present.

19. The entire specimen should be taken in one or more blocks depending on the number and size of the specimen.

20. TNM Definitions Primary tumor (pT) for papillary, follicular, poorly differentiated, Hurtle cell and anaplastic thyroid carcinomas: TX:  Primary tumor cannot be assessed T0:  No evidence of primary tumor T1:  Tumor ≤ 2 cm in greatest dimension limited to the thyroid T1a:  Tumor ≤ 1 cm in greatest dimension limited to the thyroid T1b:  Tumor > 1 cm but ≤ 2 cm in greatest dimension limited to the thyroid T2:  Tumor > 2 cm but ≤ 4 cm in greatest dimension limited to the thyroid

21. T3:  Tumor > 4 cm limited to the thyroid or gross extra thyroidal extension invading only strap muscles T3a:  Tumor > 4 cm limited to the thyroid T3b:  Gross extra thyroidal extension invading only strap muscles (sternohyoid, sternothyroid, thyrohyoid or omohyoid muscles) from a tumor of any size T4:  Includes gross extra thyroidal extension into major neck structures T4a:  Gross extra thyroidal extension invading subcutaneous soft tissues, larynx, trachea, esophagus or recurrent laryngeal nerve from a tumor of any size T4b:  Gross extra thyroidal extension invading prevertebral fascia or encasing carotid artery or mediastinal vessels from a tumor of any size

22. Primary tumor (pT) for medullary thyroid carcinomas: TX - T3:   Definitions are similar to the above T4:  Advanced disease T4a:  Moderately advanced disease; tumor of any size with gross extra thyroidal extension into the nearby tissues of the neck, including subcutaneous soft tissue, larynx, trachea, esophagus or recurrent laryngeal nerve T4b:  Very advanced disease; tumor of any size with extension toward the spine or into nearby large blood vessels, invading the prevertebral fascia or encasing the carotid artery or mediastinal vessels

23. Regional lymph node ( pN ): NX:  Regional lymph nodes cannot be assessed N0:  No evidence of regional lymph node metastasis N0a:  One or more cytological or histologically confirmed benign lymph nodes N0b:  No radiologic or clinical evidence of regional lymph node metastasis N1:  Metastasis to regional nodes N1a:  Metastasis to level VI or VII ( pretracheal , paratracheal , prelaryngeal or upper mediastinal) lymph nodes; this can be unilateral or bilateral disease N1b:  Metastasis to unilateral, bilateral or contralateral lateral neck lymph nodes (levels I, II, III, IV or V) or retropharyngeal lymph nodes

24. Distant metastasis (M): M0:  No distant metastasis M1:  Distant metastasis

25. AJCC Prognostic Stage Grouping Differentiated Thyroid Cancer: Age at diagnosis < 55 years Stage I : anyT anyN M0 Stage II : anyT anyN M1 Age at diagnosis ≥ 55 years Stage I : T1 N0/NX M0 T2 N0/NX M0 Stage II : T1 N1 M0 T2 N1 M0 T3a/ T3b anyN M0 Stage III : T4a anyN M0 Stage IVA : T4b anyN M0 Stage IVB : anyT anyN M1

26. Medullary Thyroid Cancer: Stage I : T1 N0 M0 Stage II : T2 N0 M0 T3 N0 M0 Stage III : T1 – 3 N1a M0 Stage IVA : T4a anyN M0 T1 – 3 N1b M0 Stage IVB : T4b anyN M0 Stage IVC : anyT anyN M1

27. Anaplastic Thyroid Cancer: Stage IVA : T1 - T3a N0/NX M0 Stage IVB : T1 - T3a N1 M0 T3b anyN M0 T4 anyN M0 Stage IVC : anyT anyN M1