A Dissertation submitted to the Faculty of Health Sciences of University of the Witwatersrand, Johannesburg, in fulfillment of the requirements for the degree of Master of Medicine in Surgery. Johannesburg, 2017 / Background: Hurthle cell neoplasms (HCN) are considered a variant of follicular thyroid neoplasms, and accounts for 3-10% of neoplasms of the thyroid gland. They include Hurthle cell adenomas (HCA) and carcinomas (HCC). Differentiating HCA from HCC preoperatively is currently not possible. We retrospectively searched for demographic and histopathological factors which can be used to predict the risk of malignancy in HCN. Aim: To determine the prevalence of HCC and its demographic factors and histopathological features that can be used to predict the risk of malignancy in HCN. Methods: Records of all patients who underwent thyroidectomy at Academic Hospitals associated with University of the Witwatersrand from January 2001 to October 2015 were reviewed. Patients’ demographic data and the final histology of HCN were further analyzed including pre-operative fine needle aspiration cytology (FNAC) results. Data collected included patients’ demographic, final histology, tumor size and preoperative FNAC result. Data was entered into Excel Spreadsheet and analyzed using STATICA 13.1 program. Results: At total of 2641 records of thyroidectomies were found of which 25.6% (676/2641) were for thyroid neoplasms. Only 15.8% (107/676) of the neoplasms were HCNs and 25.2% (27/107) of HCNs were HCCs. Hurthle cell carcinoma made up 5.6% (27/481) of thyroid carcinomas. 70.4% (19/27) of HCCs were incidentally found following thyroidectomy for multinodular goiter (MNG). The mean tumor size was significantly greater for carcinomas than for adenomas (4.9 cm vs. 3.5 cm; p = 0.016). The risk of malignancy increased from 11.1% when the size was less or equal to 1cm, through 33.3% for size of 1-4cm to 51.8% when the size was greater than 4cm in diameter. A total of 58 FNACs results of 107 HCNs were available for further analysis. Thirty one (53.4%: 31/58) of FNAC results were suspicious for HCN (Bethesda IV), seven (12.1%: 7/58) suspicious of papillary carcinoma (Bethesda V) and eight (13.8%: 8/58) were reported as benign (Bethesda II). Around 10.3% (6/58) were non-diagnostic (Bethesda I) whereas 8.6% (5/58) were reported as atypia of unknown significance (Bethesda III). Both HCA and HCC were more prevalent in females, 88.7% (71/80) and 77.8% (21/27); respectively. The mean age of the patients who had HCA and HCC in years was 52.3+/- 15.6 SD and 55.0 +/- 15.0 SD, respectively. Conclusion: Majority of HCCs are diagnosed following thyroidectomy for benign disease. Close to a quarter of HCNs are malignant and the risk of malignancy increases with size. Age and gender are not useful to predict malignancy in HCNs. We recommend total thyroidectomy for thyroid nodule greater than 4cm in diameter if FNAC result is suggestive of HCN as the risk of malignancy is above 50%. / MT2017

Uma série de 205 casos de lesões nodulares da tireóide foi revista morfologicamente de acordo com a nova classificação da Organização Mundial da Saúde (OMS, 2004) e analisada quanto à imuno-expressão das citoqueratinas 14 (CK 14) e 19 (CK19) e de citocromo-oxidase. Especial ênfase foi dada à avaliação da oxifilia nos nódulos, valorizando não só a oxifilia clássica (mais de 75% de células oncocíticas), mas também o que aqui chamamos de oxifilia parcial, e ao diagnóstico dos tumores foliculares de potencial incerto de malignidade. Amostras parafinadas dissecadas de carcinomas foram analisados para mutações dos genes BRAF e RAS (H-RAS, KRAS e N-RAS) mediante PCR, SSCP e seqüenciamento e para rearranjo dos genes PAX8-PPARg mediante FISH e RT-PCR. A oxifilia esteve presente, com freqüência variável, em todos os subtipos de nódulos da tireóide, benignos e malignos: 20,7 a 69,7% dos nódulos exibiram oxifilia clássica e 58,6 a 90,6% oxifilia de qualquer intensidade (clássica ou parcial). A imuno-expressão de citocromo-oxidase mostrouse associada ao achado morfológico de oxifilia, principalmente nos nódulos benignos e nos carcinomas foliculares. A CK 19 apresentou reatividade intensa apenas nos carcinoma papilíferos e em um caso de carcinoma folicular com áreas sugestivas de evolução para carcinoma pouco diferenciado. Houve associação significativa entre o diagnóstico de carcinoma papilífero e expressão de CK19 (p<0.001), mas a associação entre oxifilia e expressão de CK 19 não foi significativa. Nos carcinomas papilíferos, a oxifilia ausente ou parcial associou-se a maior freqüência de multicentricidade e a oxifilia clássica à maior idade média dos pacientes. A mutação do gene BRAF (V600E) esteve presente apenas nos carcinomas papilíferos e não teve influência nas variáveis clínico-patológicas. O rearranjo PAX8-PPARg teve incidência nas lesões foliculares oncocíticas (22,2%) bem superior à relatada na literatura. Associou-se a menor idade média dos pacientes e menor diâmetro tumoral nos carcinomas foliculares. A presença de mutações do RAS nas lesões foliculares associou-se significativamente com invasão capsular e oxifilia parcial. Todas os padrões de alterações moleculares, embora presentes, foram menos freqüentes nos tumores oncocíticos. Nossos resultados evidenciam que a oxifilia é muito freqüente em todos os subtipos de nódulos da tireóide, inclusive nos recém-descritos tumores foliculares de potencial incerto de malignidade. Merece destaque o fato de, nas lesões foliculares, a presença de oxifilia, especialmente em sua forma clássica, ter sido significativamente mais freqüente nos carcinomas, seguidos dos tumores foliculares de potencial incerto, sendo menos prevalente nos adenomas foliculares. Embora a oxifilia tenha sido associada com menor freqüência de mutações nos genes BRAF, RAS e rearranjo PAX8-PPARg, a detecção de sua coexistência com estas mutações e a presença freqüente de oxifilia em todos os tipos de nódulos da tireóide favorecem o conceito de que a oxifilia e a tumorigênese possam ser eventos distintos, muitas vezes paralelos. / A series of 205 thyroid nodules was morphologically reviewed according to the new World Health Organization (WHO, 2004) classification and analyzed regarding the immunoexpression of cytokeratins 14 (CK14) and 19 (CK19) and mitochondrial enzyme cytochrome oxidase. Special emphasis was given to the oxyphilia evaluation in the nodules, concerning not only the classical oxyphilia (more than 75% of oncocytic cells) but also the presence of smaller amounts of oncocytic cells, named herein partial oxyphilia, and to the recently purposed diagnosis of follicular tumours of unknown malignancy potential. Dissected paraffin-embedded samples of carcinomas were screened for BRAF and RAS mutations (H-RAS, K-RAS and NRAS) by PCR, SSCP and direct sequencing, whereas FISH and RT-PCR were used for assessment of PAX8-PPARg rearrangement. The oxyphilia was present, with heterogeneous frequence, in all subtypes of thyroid nodules: 20.7 to 69.7% of the nodules showed classical oxyphilia and 58.6 to 90.6% of them, oxyphilia of any intensity (classical or partial). The immunoexpression of cytochrome-oxidase was associated to the morphological finding of oxyphilia, especially in benign nodules and in follicular carcinomas. CK19 showed intense reactivity only in papillary carcinomas and in one case of follicular carcinoma with areas that could be already poorly differentiated. There was a significant association between the diagnosis of papillary carcinoma and CK 19 expression (p<0.001), but the association between oxyphilia and CK 19 expression was not statistically significant. Papillary carcinomas without or with partial oxyphilia were associated to a higher frequency of multicentricity and those with classical oxyphilia to older mean ages of patients. The BRAF gene mutation (V600E) was present only in papillary carcinomas and had no influence on clinical-pathological variables. The PAX8-PPARg rearrangement rates in oncocytic follicular lesions were higher than those previously reported. This rearrangement was associated to a younger mean age of patients and to smaller follicular carcinomas. The presence of RAS mutations in follicular lesions was significantly associated to capsular invasion and partial oxyphilia. All patterns of molecular alterations assessed herein, although present, were less frequent in oncocytic tumours. Our study further demonstrates the prevalence of classical and partial oxyphilia within all subtypes of thyroid nodules, including the recently described follicular tumours of unknown malignancy potential. A remarkable finding is that, among follicular neoplasms, oxyphilia, especially in classical pattern was significantly more prevalent in carcinomas, intermediate in follicular tumours of unknown malignancy potential and less common in adenomas. The absence of a significative relationship between oxyphilia and malignancy in most nodules is noteworthy. However, an association between oxyphilia and malignancy was observed in follicular neoplasms. Although oxyphilia has been associated with a lower mutation frequency in BRAF and RAS genes and PAX8- PPARgrearrangement, it can coexist with these mutations. This finding and the high prevalence of oxyphilia in all subtypes of thyroid nodules support the concept that oxyphilia and tumourigenesis can be distinct, and many times, parallel events.

Uma série de 205 casos de lesões nodulares da tireóide foi revista morfologicamente de acordo com a nova classificação da Organização Mundial da Saúde (OMS, 2004) e analisada quanto à imuno-expressão das citoqueratinas 14 (CK 14) e 19 (CK19) e de citocromo-oxidase. Especial ênfase foi dada à avaliação da oxifilia nos nódulos, valorizando não só a oxifilia clássica (mais de 75% de células oncocíticas), mas também o que aqui chamamos de oxifilia parcial, e ao diagnóstico dos tumores foliculares de potencial incerto de malignidade. Amostras parafinadas dissecadas de carcinomas foram analisados para mutações dos genes BRAF e RAS (H-RAS, KRAS e N-RAS) mediante PCR, SSCP e seqüenciamento e para rearranjo dos genes PAX8-PPARg mediante FISH e RT-PCR. A oxifilia esteve presente, com freqüência variável, em todos os subtipos de nódulos da tireóide, benignos e malignos: 20,7 a 69,7% dos nódulos exibiram oxifilia clássica e 58,6 a 90,6% oxifilia de qualquer intensidade (clássica ou parcial). A imuno-expressão de citocromo-oxidase mostrouse associada ao achado morfológico de oxifilia, principalmente nos nódulos benignos e nos carcinomas foliculares. A CK 19 apresentou reatividade intensa apenas nos carcinoma papilíferos e em um caso de carcinoma folicular com áreas sugestivas de evolução para carcinoma pouco diferenciado. Houve associação significativa entre o diagnóstico de carcinoma papilífero e expressão de CK19 (p<0.001), mas a associação entre oxifilia e expressão de CK 19 não foi significativa. Nos carcinomas papilíferos, a oxifilia ausente ou parcial associou-se a maior freqüência de multicentricidade e a oxifilia clássica à maior idade média dos pacientes. A mutação do gene BRAF (V600E) esteve presente apenas nos carcinomas papilíferos e não teve influência nas variáveis clínico-patológicas. O rearranjo PAX8-PPARg teve incidência nas lesões foliculares oncocíticas (22,2%) bem superior à relatada na literatura. Associou-se a menor idade média dos pacientes e menor diâmetro tumoral nos carcinomas foliculares. A presença de mutações do RAS nas lesões foliculares associou-se significativamente com invasão capsular e oxifilia parcial. Todas os padrões de alterações moleculares, embora presentes, foram menos freqüentes nos tumores oncocíticos. Nossos resultados evidenciam que a oxifilia é muito freqüente em todos os subtipos de nódulos da tireóide, inclusive nos recém-descritos tumores foliculares de potencial incerto de malignidade. Merece destaque o fato de, nas lesões foliculares, a presença de oxifilia, especialmente em sua forma clássica, ter sido significativamente mais freqüente nos carcinomas, seguidos dos tumores foliculares de potencial incerto, sendo menos prevalente nos adenomas foliculares. Embora a oxifilia tenha sido associada com menor freqüência de mutações nos genes BRAF, RAS e rearranjo PAX8-PPARg, a detecção de sua coexistência com estas mutações e a presença freqüente de oxifilia em todos os tipos de nódulos da tireóide favorecem o conceito de que a oxifilia e a tumorigênese possam ser eventos distintos, muitas vezes paralelos. / A series of 205 thyroid nodules was morphologically reviewed according to the new World Health Organization (WHO, 2004) classification and analyzed regarding the immunoexpression of cytokeratins 14 (CK14) and 19 (CK19) and mitochondrial enzyme cytochrome oxidase. Special emphasis was given to the oxyphilia evaluation in the nodules, concerning not only the classical oxyphilia (more than 75% of oncocytic cells) but also the presence of smaller amounts of oncocytic cells, named herein partial oxyphilia, and to the recently purposed diagnosis of follicular tumours of unknown malignancy potential. Dissected paraffin-embedded samples of carcinomas were screened for BRAF and RAS mutations (H-RAS, K-RAS and NRAS) by PCR, SSCP and direct sequencing, whereas FISH and RT-PCR were used for assessment of PAX8-PPARg rearrangement. The oxyphilia was present, with heterogeneous frequence, in all subtypes of thyroid nodules: 20.7 to 69.7% of the nodules showed classical oxyphilia and 58.6 to 90.6% of them, oxyphilia of any intensity (classical or partial). The immunoexpression of cytochrome-oxidase was associated to the morphological finding of oxyphilia, especially in benign nodules and in follicular carcinomas. CK19 showed intense reactivity only in papillary carcinomas and in one case of follicular carcinoma with areas that could be already poorly differentiated. There was a significant association between the diagnosis of papillary carcinoma and CK 19 expression (p<0.001), but the association between oxyphilia and CK 19 expression was not statistically significant. Papillary carcinomas without or with partial oxyphilia were associated to a higher frequency of multicentricity and those with classical oxyphilia to older mean ages of patients. The BRAF gene mutation (V600E) was present only in papillary carcinomas and had no influence on clinical-pathological variables. The PAX8-PPARg rearrangement rates in oncocytic follicular lesions were higher than those previously reported. This rearrangement was associated to a younger mean age of patients and to smaller follicular carcinomas. The presence of RAS mutations in follicular lesions was significantly associated to capsular invasion and partial oxyphilia. All patterns of molecular alterations assessed herein, although present, were less frequent in oncocytic tumours. Our study further demonstrates the prevalence of classical and partial oxyphilia within all subtypes of thyroid nodules, including the recently described follicular tumours of unknown malignancy potential. A remarkable finding is that, among follicular neoplasms, oxyphilia, especially in classical pattern was significantly more prevalent in carcinomas, intermediate in follicular tumours of unknown malignancy potential and less common in adenomas. The absence of a significative relationship between oxyphilia and malignancy in most nodules is noteworthy. However, an association between oxyphilia and malignancy was observed in follicular neoplasms. Although oxyphilia has been associated with a lower mutation frequency in BRAF and RAS genes and PAX8- PPARgrearrangement, it can coexist with these mutations. This finding and the high prevalence of oxyphilia in all subtypes of thyroid nodules support the concept that oxyphilia and tumourigenesis can be distinct, and many times, parallel events.

No description available.