Epidemiology and the Histopathological Pattern of Diagnosis of Thyroid Diseases in a University Hospital in Riyadh , Saudi Arabia

Abstract Background/Aims: Thyroid disorders are a common, worldwide clinical problem in general practice. It presents predominantly as a thyroid nodule. Each thyroid nodule has a risk of cancer. The incidence of thyroid cancer is much more common in Saudi Arabia in comparison to the West. There is a worldwide increase in the incidence of thyroid cancer. The objective of this study is to highlight in details the wide spectrum of histopathologic diagnosis encountered in patient undergoing thyroid surgery in the population of Riyadh region of Saudi Arabia. Patients and Methods: Retrospective review of all thyroid samples for 256 patients whom underwent thyroid surgery at King Khalid University Hospital, King Saud University, Riyadh, during the period between 2000 and 2009. Of those, 171 cases were non neoplastic and 85 neoplastic lesions. Females constitute 80% of non neoplastic lesions and 79% of all thyroid malignancies. The peak incidence of thyroid cancer was in the third decade. Papillary thyroid carcinoma was the most common cancer (71%). Conclusion: Thyroid cancer is a common cancer in Saudi Arabia; it is the second most common cancer in females. The increasing rates of thyroid cancer occur predominantly in women. Papillary thyroid carcinoma accounted for the bulk of this increase. Additional studies are needed to explain the rise in papillary thyroid carcinoma incidence in Saudi Arab as well as throughout the world and to search potential risk factors that are currently unrecognized. DOI : 10.14302/issn.2372-6601.jhor -14-382


Introduction:
After diabetes mellitus, among the endocrine organs disorders, thyroid lesions are quite commonly encountered in the clinical practice. Thyroid nodules are very common and of concern (because of the risk of malignancy and hyperfunction) occurring in 3% of the population, more commonly in females and in areas of iodine deficiencies. Almost one third of the world's population lives in the areas of iodine deficieny 1  Thyroid neoplasms account for only 1% of the overall human cancer burden, however they represent the most common malignancies of the endocrine systems (90% of all endocrine cancers).They are responsible for more deaths than any other endocrine cancers 3 .
According to 2012 United States cancer statistics reporting, thyroid cancer is expected to be the 5th most commonly diagnosed cancer among women. The incidence of thyroid cancer is much more common in Saudi Arabia (SA) as compared to the western world. It is the second most common malignancy after breast cancer in female patients 4   All patients presenting with thyroid swelling and undergoing any type of thyroid operation were included in the study. Those patients in whom fine needle aspiration cytology (FNAC) was done but they did not undergo thyroid surgery were excluded from the study.  Solitary benign adenomas were found in 23 cases, the peak frequency was fourth and fifth decade.

Material and Methods
Female accounted for 12 cases (70.5%) for follicular adenoma ( Figure 2) and 3 cases (50%) for Hurthle cell adenoma. Thyroid malignancy and it was reported in 62 cases. Papillary carcinoma (Figure 3) was the most common type of thyroid malignancy found in 44 cases (71%) followed by follicular carcinoma (9.6%) ( Figure   4), medullary carcinoma (1.6) and poorly differentiated carcinoma (1.6%) (Table3). The peak incidence for patients with thyroid malignancy in this series was third decade and male to female ratio was 3.7:1.

Discussion:
Thyroid disorders are one of the common problems encountered in clinical practice with majority of them benign in nature. Today thyroidectomy is a routine procedure because of the introduction of safe anesthesia, antiseptics, fine surgical instruments and developments of new techniques, offering the chances of cure to many patients 8,9 .
In this study, multi nodular goiter contributed 122 cases (47.6%) forming the most common presenting pathologic presentation. A high incidence of multi nodular goiter was also reported in Bisha 10 , Jeddah 11 and Asir 12 region of SA and Pakistan 13 .
However in a study published from Nigeria 9 reported colloid goiter to be the most common type of benign pathology in thyroid.       Thyroid cancer incidence is increasing throughout the world. Most studies attribute this rise entirely to the increase in papillary thyroid carcinoma incidence, the most common thyroid malignancy in iodine sufficient areas. Some researchers suggest that this rise is only apparent due to an increase in diagnostic activity.

Conclusion:
In SA, in past several decades, there is relative increase in the incidence of both non neoplastic and neoplastic disorders. This data should be taken into account when planning the health resources for these patients. Additional studies are needed to explain the rise in papillary thyroid carcinoma incidence in SA as well as throughout the world and to search potential risk factors that are currently unrecognized.