challenge is to distinguish the few clinically significant malignant nodules from many benign ones (Table 1).

Transcription

1 Indian Journal of Mednodent and Allied Sciences Vol. 3, No. 2, June 2015, pp IndianJournals.com A product of Diva Enterprises Pvt. Ltd. DOI : / Original Research Ultrasound Evaluation of Thyroid Lesions Mohammed Ismail Syed 1, K. Janardhan Reddy 2, Mahalaxmi 3, Y. Aditya 4 *, M.V. Ramanappa 5 ABSTRACT This study was done at Santhiram general hospital. 57 patients with thyroid swelling were examined with ultrasound and followed up with FNAC. Findings were analyzed which showed that 14 were cystic, 27 solid and 16 were mixed lesions; 93% of cystic lesions were benign (Table 2). Among solid lesions 83% were benign rest malignant. Among mixed lesions 87.75% benign and only 12.25% were malignant (Table 3). Ninty two per cent of goiter showed calicification papillary; carcinoma case showed calicification. Hypoechoic hallow showed 88% benign lesions and 12% of malignant lesions; hence US has a definete role in charecterising thyroid lesions. It is being cheap and readily available. The characterisation of perilesion halo is whether irregular or smooth which helps in differentiating benign and malignant nature of lesion. It helps in FNAC for exact localisation. KEYWORDS: Papillary, Carcinoma, Ultrasonography, Hyperplasia, Goiter, FNAC, Follicular carcinoma, Thyroid diseases INTRODUCTION Thyroid swelling is a common clinical problem routinely encountered in the outpatient department. Most of the messes are the result of diffuse enlargement of thyroid gland (diffuse colloid goiter) commonly seen at puberty, lactation etc. Other pathological lesions such as thyroid neoplasm also present in the form of enlarged thyroid mass or thyroid nodule. Various immunological diseases of the thyroid including hypo and hyper thyroid states may present as thyroid enlargement. Advantage of Ultrasonography over Clinical Examination 1. Ultrasonography provides a better anatomical representation of the thyroid gland with remarkable clarity due to the superficial location of the gland (Figure 1). It can reveal the nature of the mass (cystic vs. solid). It can reveal the number of nodules i.e., whether the lesion is a solitary nodule or is it a palpable nodule that is a part of multi nodular goiter [1]. 2. Ultrasound is helpful in detecting calcification and the pattern of calcification. It is helpful in assessing the vascularity of the lesion. 3. Invasion of the adjacent structures by the thyroid mass can be known by ultrasonography. Lymph node status is better evaluated with ultrasound. Nodular Thyroid Disease [2] Many thyroid diseases can be present clinically with one or more thyroid nodules. Exposure to ionising radiation increases the incidence of benign and malignant nodules with 20 30% of radiation exposed disease is relatively common; thyroid cancer is rare and accounts for less than 1% of all malignant neoplasms. Majority of thyroid nodules are benign. The 1,2,4 Assistant Professor, 5 Professor and Head, 3 Senior Resident Department of Radiodiagnosis, Santhiram Medical College and General Hospital, NH-18, Nandyal, Kurnool District, Andhra Pradesh, India *Corresponding author id: yadlapalliaditya@yahoo.com 71

2 Mohammed Ismail Syed, K. Janardhan Reddy, Mahalaxmi, Y. Aditya, M.V. Ramanappa challenge is to distinguish the few clinically significant malignant nodules from many benign ones (Table 1). Table 1: Incidence of different types of thyroid lesions on sonography depending on internal content Types of lesion on sono- No. of cases Percentage graphic examination Cystic Solid Mixed Total Most of the lesions in our study are solid Table 2: Sonographic features of different types of cystic lesions Sonographic Goiter Papillary Haemorfeature with cystic carcinoma rhagic degen- (cystic) cyst eration Shape Round 1 Oval 7 1 Irregular 4 1 Margins Regular 8 1 Irregular Echotexture Hypo 11 1 Hyper 0 Iso 0 Mixed Calcification Intra-cystic septations Hypoechoic halo Lymphadenopathy Distant metastasis Total Goiter with cystic degeneration is mostly oval in shape, with regular margins and hypoechoic in nature, whereas cystic type of papillary carcinoma is irregular with irregular borders and associated with lymphadenopathy. Hyperplasia and Goiter [3] Approximately 80% of nodular thyroid disease is due to hyperplasia of the gland and it occurs in upto 5% of any population. Sonographically, most hyperplastic or adenomatous nodules are isoechoic compared to normal thyroid tissue. As the size of the mass increases, it may become hyperechoic due to the numerous interfaces between the cells and colloid substance. A thin peripheral hypoechoic halo is commonly seen and it is most likely due to perinodular blood vessels and mild oedema or compression of the adjacent normal parenchyma (Figure 2). Adenoma Adenoma represents only 5 10% of all nodular disease of the thyroid and is seven times more common in females than in males. Most adenomas are solitary may be a multi nodular process. Sonographically, adenomas are usually solid masses that may be hyperechoic, isoechoic or hypoechoic. They often have a hypoechoic halo that is thick and smooth. Carcinoma [5,9] Papillary carcinoma: They are the most common type of thyroid cancer and account for 75 90% of all thyroid malignancies. The sonographic characteristics of papillary carcinoma are relatively distinctive in most cases. They include: 1. Hypoechogenicity. 2. Microcalcifications that appear as tiny, punctuate hyperechoic foci, either with or without acoustic shadowing. 3. Hyper vascularity (in 90% of the cases) with disorganised vascularity. 4. Cervical lymph node metastasis which may contain tiny, punctuate echogenic foci due to microcalcifications and cystic due to extensive degeneration (Figure 8 and 9). Follicular carcinoma: This accounts for 5 15% of all cases of thyroid cancer, affecting females more often 72 Vol. 3, No. 2, June 2015

3 Ultrasound Evaluation of Thyroid Lesions Figure 4: Goiter with cystic degeneration showing comet tail artifact which is mixed echogenic, oval shaped Figure 1: Ultrasound picture of normal thyroid Figure 2: Haemorrhagic cyst thyroid parenchyma showing well-defined cystic oval mixed echogenic lesion with fluid debris level Figure 5: Colloid goiter Figure 3: Colloid nodule with cystic degeneration showing comet tail appearance Figure 6: Colloid goiter solid isoechoic nodule in thyroid with peripheral halo Indian Journal of Mednodent and Allied Sciences 73

4 Mohammed Ismail Syed, K. Janardhan Reddy, Mahalaxmi, Y. Aditya, M.V. Ramanappa Figure 7: Follicular adenoma showing peripheral flow on colour Doppler Figure 10: Hashimotos thyroiditis thyroid parenchyma showing hypoechoic nodules Figure 8: Papillary carcinoma mixed echoic lesion with microcalcifications and lymph node Figure 9: Photomicrograph of papillary carcinoma Figure 11: Histopathological picture of Hashimotos thyroiditis mixture of degenerating follicles with lymphocytes than males. There are two variants namely the minimally invasive and the widely invasive groups with irregular tumour margins (Figure 7). 1. Hypo, iso or mixed echotextured mass. 2. Thick, irregular halo. 3. Tortuous or chaotic arrangement of internal blood vessels on colour Doppler. Medullary carcinoma: This accounts for only 5% of all malignant thyroid disease. It is derived from the para follicular cells or the C cells and typically secretes 74 Vol. 3, No. 2, June 2015

5 Ultrasound Evaluation of Thyroid Lesions the hormone calcitonin. There is a high incidence of metastatic involvement of lymph nodes. The sonographic appearance of medullary carcinoma is similar to that papillary carcinoma. Anaplastic thyroid carcinoma [7] : It accounts for less than 5% of all thyroid cancers and is typically a disease of the elderly. Of all the thyroid carcinomas, it carries the worst prognosis. Sonogrpahically these carcinomas are usually hypoechoic and are often seen to encase carcinomas and are usually hypoechoic and encase or invade blood vessels and invade neck muscles (Table 3). Lymphoma: It accounts for approximately 4% of thyroid malignancies. It is of non-hodgkin s type and usually affects older females. Diffuse Thyrod Disease Several thyroid diseases are characterised by diffuse rather than focal involvement. This usually results in generalised enlargement of the gland (goiter) and no palpable nodules. Conditions: Chronic autoimmune lymphocytic (Hashimoto s) thyroiditis, colloid or adenomatous goiter and Graves disease. Diagnosis of these conditions is usually made on the basis of clinical and laboratory findings and on occasion by FNAC (Figure 10, 11). Acute suppurative thyroiditis: It is a rare inflammatory disease that is usually cause by bacterial infection. Sonography shows abscess. Sub-acute granulomatous thyroiditis: It is a spontaneously remitting disease that is probably causes by viral infection. Sonographically the gland may appear enlarged and hypoechoic with normal or decreased vascularity due to diffuse oedema of the gland. Adenomatous goiter [8] : Although sonographic appearance of adenomatous goiter can be similar to Hashimoto s thyroiditis, some patients with adenomatous goiter have multiple disecrete nodules separated by otherwise normal appearing parenchyma. Table 3: Incidence and types of solid lesions observed on sonographic examination and their correlation with FNAC Types of lesion Sonographic FNAC diagnosis diagnosis Colloid goiter 6 2 Follicular adenoma 7 8 Papillary carcinoma 4 5 Hashimoto s thyroiditis Total Sonographic diagnosis correlates well with FNAC findings. Table 4: Sonographic features of different types of solid lesions Sonographic Colloid Folli- Papillary Hashifeature goiter cular carci- moto adenoma noma sthyroiditis Shape Round Diffuse 10 Oval Irregular Margins Regular Irregular Echotexture Hypo Hyper Iso Mixed Calcification Hypoechoic halo Lymphadenopathy Distant metastasis Total Total 27. Riedel s struma: This is the rarest type of inflammatory thyroid disease. Sonographically the gland is diffusely enlarged and has an in homogenous parenchymal echotexture. Indian Journal of Mednodent and Allied Sciences 75

6 Mohammed Ismail Syed, K. Janardhan Reddy, Mahalaxmi, Y. Aditya, M.V. Ramanappa MATERIALS AND METHODS Fifty-seven patients of clinically suspected thyroid masses were sent to radiology department from General surgery and E.N.T. units in Santhiram Medical College and General Hospital. Methods of Examination of the Thyroid Sonography Study was conducted in patients who presented with a swelling in front of the neck. Longitudinal and transverse scans of the thyroid gland were done with the patient in supine position and head in hyperextension. The entire gland including the isthmus was examined. The examination has also been extended laterally to include the region of the carotid artery and the jugular vein in order to identify enlarged jugular chain lymph nodes. Analysis of the Results of the Study The present study includes 57 patients referred to our department for ultrasonographic examination of various thyroid masses for which FNAC was done. During the same period a total of 140 cases of thyroid scans were done. The rest of the cases were not included in the study, as FNAC was not done for the cases. Major affected age group is between 11 and 50 year. TREFERENCES [1] Ahuja A, Chick W, and King W et al. Clinical significance of the comet tail artifact in thyroid ultrasound, J Clin Ultrasound 1996;24: [2] Alexander EK, Marqusee E, Orcutt J, Benson CB et al. Thyroid nodule shape and predication of malignancy. Thyroid 200;14(11): [3] Brklijacic B, Cuk V, Brzac HT et al. Ultrasound evaluation of benign and malignant nodules in echo graphically multinodular thyroids, J Clin Ultrasound 1994;22(2):71-6. [4] Carmeci C, Jeffrey RB, Mc Dougall IR et al. Ultrasound - guided fine needle aspiration biopsy of thyroid masses. Thyroid 1998;8(4): [5] Chan BK, Desser TS, Mc Dougall IR et al. Common and uncommon sonographic features of papillary thyroid carcinoma, J Ultrasound Med 2003;22: [6] Chang TC, Hong CT, Chang SL. Correlation between sonography and pathology in thyroid diseases. J Formos Med Assoc 89: [7] Ganesan S. Pictorial Essay: sonographic patterns of cervical nodal disease in papillary thyroid carcinoma. Ind J Radiol Imag 2000;10(1): [8] Hayashi N, Tamaki N, Konishi J et al. Sonography of Hashimoto s thyroiditis, J Clin Ultrasound 1986;14(2): [9] Lannuccilli JD, Cronan JJ, Monchil JM. Risk of malignancy of thyroid nodules as assessed by sonographic criteria: the need for biopsy. J Ultrasound Med 2004;23(11): Vol. 3, No. 2, June 2015