Distinguish Thyroid Malignant from Benign Alterations using Trace Element Contents in Nodular Tissue determined by Neutron Activation and Inductively Coupled Plasma Mass Spectrometry Journal of Clinical and Diagnostic Pathology

of Ga, and Rb 62%, 51%, 33%, respectively, than Abstract Background Thyroid benign (TBN) and malignant (TMN) nodules are a common thyroid lesion. The differentiation of TMN often remains a clinical challenge and further improvements of TMN diagnostic accuracy are warranted. The aim of present study was to evaluate possibilities of using differences in trace elements (TEs) contents in nodular tissue for diagnosis of thyroid malignancy. Distinguish between Thyroid Malignant and Benign Nodules


Introduction
Nodules are a common thyroid lesion, particularly in women. Depending on the method of examination and general population, thyroid nodules (TNs) have an incidence of 19-68% [1]. In clinical practice, TNs are classified into benign (TBN) and malignant (TMN), and among all TNs approximately 10% are TMN [2]. It is appropriate mention here that the incidence of TMN is increasing rapidly (about 5% each year) worldwide [2].
Surgical treatment is not always necessary for TBN whereas surgical treatment is required in TMN. Thus, differentiating TBN and TMN will have a great influence on thyroid therapy.
Ultrasound scan (USS) examination is widely used as the primary method for early detection and diagnosis of the TNs. However, there are many similarities in the USS characteristics of both TBN and TMN. For misdiagnosis prevention some computer-diagnosis systems based on the analysis of USS images were developed, however as usual these systems for the diagnosis of TMN showed accuracy, sensitivity, and specificity nearly 80% [2,3].
Therefore, when USS examination shows suspicious signs, an US-guided fine-needle aspiration biopsy is advised.
Despite the fact that fine needle aspiration biopsy has remained the diagnostic tool of choice for evaluation of USS suspicious thyroid nodules, the differentiation of TMN often remains a diagnostic and clinical challenge since up to 30% of nodules are categorized as cytologically "indeterminate" [4]. Thus, to improve diagnostic accuracy of TMN, new technologies have to be developed for clinical applications. However, a recent systematic review and meta-analysis of molecular tests in the preoperative diagnosis of indeterminate TNs has shown that presently there is no perfect biochemical, immunological, and genetic biomarkers to discriminate malignancy [5].
Therefore, further improvements of TMN diagnostic accuracy are warranted.
During the last decades it was demonstrated that besides iodine deficiency and excess many other dietary, environmental, and occupational factors are associated with the TNs incidence [3,[6][7][8][9][10][11]. Among these factors a disturbance of evolutionary stable input of many trace elements (TEs) in human body after the industrial revolution plays a significant role in etiology of TNs [12].
Besides iodine, many other TEs have also essential physiological role and involved in thyroid functions [13].
Essential or toxic (goitrogenic, mutagenic, carcinogenic) properties of TEs depend on tissue-specific need or tolerance, respectively [13]. Excessive accumulation or an imbalance of the TEs may disturb the cell functions and may result in cellular proliferation, degeneration, death, benign or malignant transformation [13][14][15].

Material and Methods
All patients suffered from TBN (n=79, mean age M±SD was 44±11 years, range 22-64) and from TMN (n=41, mean age M±SD was 46±15 years, range  were hospitalized in the Head and Neck Department of the  All tissue samples obtained from TBN and TMN were divided into two portions using a titanium scalpel to prevent contamination by TEs of stainless steel [52]. One was used for morphological study while the other was intended for TEs analysis. After the samples intended for TEs analysis were weighed, they were freeze-dried and homogenized [53]. To determine contents of the TEs by comparison with a known standard, biological synthetic standards (BSS) prepared from phenol-formaldehyde resins were used [54]. In addition to BSS, aliquots of commercial, chemically pure compounds were also used as standards. human thyroid [27,28] and scalp hair [55].  [84] and ash (4.16% on dry mass basis) [85] contents in thyroid of adults.
On the other hand, when destructive analytical techniques are used the tissue samples may be contaminated by TEs  M -arithmetic mean, SD -standard deviation, (n)* -number of all references, (n)** -number of samples.