Thursday, 28 November 2013

Thyroid Disease : Hashimoto’s thyroiditis – The Misdiagnosis

Thyroid disease is defined as a condition of malfunction of thyroid. Hyperthyroidism is a condition in which the thyroid gland is over active and produces too much thyroid hormones. Hypothyroidism is a condition in which the thyroid gland is under active and produces very little thyroid hormones. Thyroid cancer is defined as condition in which the cells in the thyroid gland have become cancerous.
Hashimoto’s thyroiditis (chronic lymphocytic thyroiditis)
Hashimoto’s thyroiditis is an autoimmune disease in which the immune system attacks the thyroid gland of that mostly often leads an underactive thyroid gland (hypothyroidism). According to the study by the University of Pisa, Women with Hashimoto’s thyroiditis (HT) suffer from a high symptom load independently from hypothyroidism, which results just a contributing factor to the development of the clinical syndrome. In agreement with these results, we recently reported on the presence of symptoms and signs consistent with fibromyalgia (FM) in patients with HT regardless thyroid dysfunction, focusing to the weight of anti-thyroid autoimmunity in the HT-associated clinical syndrome(a).
D.1. Misdiagnosis
Fine-needle aspiration (FNA) cytology in the evaluation of thyroid lesions with diagnostic accuracy of 98.6% with 100% sensitivity, 98.6% specificity, 80% positive predictive value, and 100% negative predictive value. FNA is extremely valuable in the initial evaluation of thyroid swelling in children(19).
1. Overlapping thyroid follicular lesions coexisting with Hashimoto’s thyroiditis
In the study the types and incidence of thyroid follicular lesions coexisting with Hashimoto’s thyroiditis (HT). showed that FNA diagnosed accurately the coexisting lesions in 6 cases; 3 FA, 1 FVPC, and 2 GN, but it did not sample HT. In one case, FNA diagnosed correctly both HT and the coexisting FA. Therefore, the presence of a coexistent neoplasm or goitrous nodule reduced the chances of sampling HT by 85.7%, with no false-negative results. Indeed, aspiration on and around the thyroid nodule helps in sampling HT. However, HT may dominate the smear and obscure neoplasia. This can be avoided if the procedure is performed by the pathologist and the aspiration is done on the nodule only. The overlapping cytological features of FN and HT were the main causes of false-positive results. This can be reduced by avoiding the diagnosis of FN in the presence of follicular-cell pleomorphism and/or moderate to excessive numbers of lymphoid cells, provided proper aspiration technique is maintained(20).
2. Follicular neoplasm or colloid nodule
An association between papillary thyroid carcinoma (PTC) and Hashimoto’s thyroiditis (HT) is well recognized. Both entities may often display overlapping morphologic features. In the study to evaluate the accuracy of fine needle aspiration (FNA) of concomitant PTC and HT, showed that the remaining cases (13 cases) showed diagnostic features of PTC in 2 cases (interpretation errors), some features of PTC in 8 cases (insufficient diagnostic features), features of only HT in 2 cases, and 1 case was acellular (sampling errors). Originally, 10 cases with features of PTC were diagnosed as either follicular neoplasm or colloid nodule with or without HT. Histologically, 1 of 13 cases was a cystic variant and 7 of 13 cases were follicular variants of papillary carcinoma. It is important to be aware of the coexistence of PTC and HT. Deliberate search for evidences of PTC in every case of HT may be necessary to improve diagnostic accuracy of the FNA(21).
3. Hürthle cell adenomas, follicular adenoma, nodular goiter, macrofollicular adenoma and malignant lymphoma
In the study to determine the accuracy of cytologic interpretation in the diagnosis of Hashimoto’s thyroiditis (HT), indicated that in 27 (69%) aspirates, HT was diagnosed on both the FNAB and surgical specimens. In 10 of 27 FNABs an associated lesion was not sampled by FNAB. In four of these 10 aspirates some of the cellular features of HT were misinterpreted, and the possibility of an associated neoplasm could not be ruled out. This resulted in four false positive diagnoses. In 12 (31%) FNABs from nine patients, the cytologic diagnosis of HT was not confirmed histologically. These cases included five Hürthle cell adenomas and one case each of follicular adenoma, nodular goiter, macrofollicular adenoma and malignant lymphoma. This resulted in five false negative diagnoses(22).
4. Solitary thyroid nodule
There is a rerort of a a 56-year-old female with solitary thyroid nodule diagnosed as Hurthle cell neoplasm on FNAC, but subsequent histopathological diagnosis following resection revealed Hashimoto’s thyroiditis with marked Hurthle cell change(22a).
Fatty Liver And Obesity Reversal
Use The Revolutionary Findings To Achieve 
Optimal Health And Loose Weight

Back to General health

Back to Kyle J. Norton Home page


No comments:

Post a comment