PDTC, earlier known as insular carcinoma
, is considered to have intermediate prognostic implication (between well differentiated and anaplastic carcinoma) [8,9].
Histological examination revealed only follicular and oxyphilic variants of multifocal papillary carcinoma (at least six foci) and none of insular carcinoma, with dimensions ranging from 2 to 15 mm, without signs of hematogenic, lymphatic, or perineural permeation, as well as no signs of invasion of the capsule or extrathyroidal extension, with resection margins uninvolved by tumour (pT1b[m]NxM1R0) (Figure 4).
However, the histological examination of the excised bone metastasis revealed insular carcinoma foci, suggesting primary tumour dedifferentiation during the process of distant metastization.
(33) In another institution, metastatic disease with cystic foci was seen in patients with synovial sarcoma, hepatocellular carcinoma and insular carcinoma
of the thyroid gland.
Under the malignant category, there were seven cytologically diagnosed cases: four cases of papillary carcinoma, two cases each of anaplastic carcinoma and medullary carcinoma, and a single case of insular carcinoma, respectively.
of cases Percentage (%) Colloid cyst/cystic colloid nodule 20 13.60 Colloid goiter 86 58.5 Hyperplastic nodule/adenomatoid goiter 3 2.04 Thyroglossal cyst 5 3.40 Infected cystic lesion 1 0.68 Granulomatous thyroiditis 2 1.36 Lymphocytic thyroiditis 4 2.72 Intra-thyroid reactive lymph node 1 0.68 Follicular neoplasm 3 2.04 Papillary carcinoma 4 2.72 Anaplastic carcinoma 2 1.36 Medullary carcinoma 2 1.36 Insular carcinoma 1 0.68 Table 3: Diagnostic categorization of thyroid FNACs Categories Total no.
This better differentiated tumor is usually a papillary carcinoma or one of its variants (particularly Warthin-like and tall cell variant), but it may also be a follicular carcinoma, as well as an oncocytic carcinoma, or an insular carcinoma [4, 26, 84, 85].
The small cell category, that was included in older classification of ATC, is no longer considered, as it comprised cases of bona fide lymphomas, medullary carcinomas, and insular carcinomas [2, 3, 5].
This subtype of tumors has been categorized as poorly differentiated or insular carcinoma
, based on its characteristic cell groupings.
of Cases Hyperplastic nodule 1 Goiter 4 Adenoma 3 Hurthle cell adenoma 5 PTC, usual 14 PTC, solid 2 PTC, Warthin-like 1 PTC, follicular variant 15 PTC, tall cell 5 PTC, columnar 1 PTC, diffuse sclerosing 2 PTC, microcarcinoma 2 Metastatic PTC 3 Follicular thyroid carcinoma 3 Hurthle cell carcinoma 8 Poorly differentiated carcinoma 1 Anaplastic carcinoma 2 Insular carcinoma
2 Medullary thyroid carcinoma 1 * PTC indicates papillary thyroid carcinoma.
The tumors were classified according to current criteria into the following categories: follicular carcinoma, papillary carcinoma, Hurthle cell carcinoma, insular carcinoma
, anaplastic carcinoma, and medullary carcinoma (Table 1).
Nearly 100% of thyroid carcinomas, including papillary carcinomas, follicular carcinomas, insular carcinomas
, and medullary carcinomas, are positive for TTF1.