Benign follicular thyroid lesions versus follicular variant of papillary carcinoma: differentiation by architectural pattern

Differentiation between benign and malignant follicular lesions is one of the difficult diagnostic areas in thyroid fine needle aspiration (FNA). Nuclear criteria are usually used to distinguish between them. In this study the microarchitectural pattern of common benign follicular lesions, namely nodular hyperplasia (NH) and follicular adenoma (FA) were analysed in comparison with those of follicular variant of papillary carcinoma (FVPC) in order to aid in their differentiation. The FNA smears of histologically proven cases of FVPC, NH and FA were reviewed and compared. The microarchitectural features of FVPC, NH and FA were described. Three cytological features--multi-layered rosettes, branching monolayered sheets and balls of thick pinkish colloid--were exclusively observed in FVPC. Hyperplastic papillae with intact follicles and colloid were frequently seen in NH, 83% and 100%, respectively. Albeit less frequently, they were also noted in FVPC, 25% and 75% of cases, respectively. These overlapping features make the distinction between FVPC and NH sometimes difficult; however, assessing the smears for the specific features of FVPC may help in their differentiation. None of the aforementioned microscopic findings with the exception of the seldom presence of colloid were documented in FA. The crowded clusters of follicular cells were seen both in FA and FVPC; however, they were complex and branching in the latter and round to oval in the former. Finally, smears with good recovery of material are indispensable for the identification of these helpful microarchitectural patterns.     

Atypical follicular cells with equivocal features of papillary thyroid carcinoma is not a low-risk cytologic diagnosis

Objective: To determine whether or not significant differences in the risk of malignancy exist between subgroups of atypical follicular cells in The Bethesda System for Reporting Thyroid Cytology (TBSRTC) in patients who underwent surgical resection. Study Design: Between 2004 and 2009, consecutive thyroid fine-needle aspirates at our institutions with a cytologic diagnosis of 'atypical follicular cells' were retrieved and subclassified using the diagnosis and diagnostic comment as: (1) atypical follicular cells with equivocal features of papillary carcinoma [cannot exclude papillary thyroid carcinoma (PTC)] and (2) atypical follicular cells, other patterns. The risks of malignancy for excised nodules were calculated and comparisons were made between these subgroups. Categorical analysis was performed using a 2-tailed Fisher's exact test, and p < 0.05 was considered statistically significant. Results: A total of 7,072 thyroid fine-needle aspiration cases were retrieved, with 1,542 (21.8%) having a histologic follow-up. There were 222 (3.1%) cases of 'atypical follicular cells', with 127 (57.2%) having a histologic correlation and 33 having confirmed malignancies. Atypical follicular cells, cannot exclude PTC, have a significantly higher risk of malignancy than atypical follicular cells, other patterns (45.8 vs. 13.9%, p < 0.01). Conclusions: Atypical follicular cells with equivocal features of papillary carcinoma is not a low-risk cytologic diagnosis.     

Fine needle aspiration cytology of follicular variant of papillary carcinoma of thyroid

In this retrospective study, we tried to ascertain the fine needle aspiration cytology (FNAC) features of six histopathologically proven cases of the follicular variant of papillary carcinoma of thyroid (FVPCT). These proven cases were diagnosed from 1998-2000. May-Grunwald-Giemsa and haematoxylin & eosin stained FNAC smears were studied independently by two observers (MP and PD) for detailed cytological features. A comparison of the cytological features was undertaken with those reported in the literature. There were six cases of which only one case was diagnosed as FVPCT while the other five cases were diagnosed as follicular neoplasm (four cases) and neoplasm unclassifiable (one case) on FNAC smears. All these cases showed abundant cellularity with a prominent follicular pattern. No papillae were identified in any of the cases. Syncytial clusters (five cases), nuclear grooves (six cases), nuclear inclusions (one case) and chewing gum colloid (three cases) were noted in variable proportions. We suggest that a differential diagnosis of FVPCT should be considered if the cytology smears show abundant cellularity, syncytial clusters and follicular arrangement along with thick colloid.     

Cytologic findings in the follicular variant of papillary carcinoma of the thyroid.

Fine needle aspirates from 8 thyroid papillary carcinomas, follicular variant, were studied. Histologically the tumors were composed exclusively of follicles (four cases) or an admixture of follicular and trabecular structures (four cases). Follicles were identified in smears from seven cases (87.5%) and sheets reminiscent of a trabecular pattern in one (12.5%). Colloid material presented as intraluminal (one case) or extraluminal, dense, round masses (six cases). Nuclear cytoplasmic inclusions occurred in seven (87.5%) of the cases. All these features have been described for follicular lesions or neoplasia together with occasional nuclear grooves, as occurred in two (25%) of the studied cases. In the other six (75%) cases, a moderate to high proportion of neoplastic cells with nuclear grooves facilitated the diagnosis of papillary carcinoma. Our findings suggest that a careful microscopic search for nuclear grooves should be attempted in aspirates yielding a diagnosis of follicular neoplasia that could otherwise be indistinguishable from the follicular variant of papillary carcinoma of the thyroid.     

Proliferative activity in endometrial hyperplasia and adenocarcinoma

Studies on the proliferative activity of cells in endometrial hyperplasia and adenocarcinoma were performed using techniques detecting Proliferating Cell Nuclear Antigen (PCNA) and Nucleolar Organizer Regions (NORs). PCNA expression was defined as the percentage of nuclei showing reactivity in 200 cells per sample. The mean AgNOR count per cell was calculated following the analysis of at least 100 nuclei per sample at a magnification of x 400. Student-t test was used for the statistical analysis. The results obtained indicate that the evaluation of cell proliferative activity expressed by AgNOR count and PCNA index can help in the distinction between atypical hyperplasia and well-differentiated adenocarcinoma, and thus can serve as a useful pathological criterion.     

Thyroglobulin may affect telomerase activity in thyroid follicular cells

Telomerase (TA) activity is known to be present in malignant tumor cells, but not in most somatic differentiated cells. TA shows relatively high activity in thyroid cancer cells, but reports vary. This fact prompted us to elucidate whether cell component inhibitors of TA in the thyroid follicles can modulate its activity. The activity of TA extracted from Hela cells was inhibited by mixing with the supernatant fraction of human thyroid tissue extract. To examine the effect of iodine, thyroid hormones (l-T3 and l-T4) and human thyroglobulin (hTg) contained in the thyroid follicles, l-T3, l-T4 and hTg were added to the TRAP assay system in vitro, using TA from Hela cells. Iodine, l-T3 and l-T4 did not affect TA activity, but hTg inhibited the TA activity in a dose-dependent manner (IC(50) of hTg: ca 0.45 microM: inhibiting concentration of hTg was from 0.15 microM to 3.0 microM). The hTg inhibition was not evident in the RT-PCR system, suggesting no effect of hTg on Taq DNA polymerase activity. The hTg inhibition of TA activity was attenuated by dNTP but not significantly by TS primer. These data suggest that hTg contained in thyroid follicular cells of various thyroid diseases may affect the TA activity measured in biopsied thyroid specimens, and that the reduction of the TA activity by hTg may induce slow progression and growth, and low grade malignancy of thyroid cancer, particularly differentiated carcinoma.     

Thyroglobulin may affect telomerase activity in thyroid follicular cells

Telomerase (TA) activity is known to be present in malignant tumor cells, but not in most somatic differentiated cells. TA shows relatively high activity in thyroid cancer cells, but reports vary. This fact prompted us to elucidate whether cell component inhibitors of TA in the thyroid follicles can modulate its activity. The activity of TA extracted from Hela cells was inhibited by mixing with the supernatant fraction of human thyroid tissue extract. To examine the effect of iodine, thyroid hormones (?-T3 and ?-T4) and human thyroglobulin (hTg) contained in the thyroid follicles, ?-T3, ?-T4 and hTg were added to the TRAP assay system in vitro, using TA from Hela cells. Iodine, ?-T3 and ?-T4 did not affect TA activity, but hTg inhibited the TA activity in a dose-dependent manner (IC₅₀ of hTg: ca 0.45 μM: inhibiting concentration of hTg was from 0.15 μM to 3.0 μM). The hTg inhibition was not evident in the RT-PCR system, suggesting no effect of hTg on Taq DNA polymerase activity. The hTg inhibition of TA activity was attenuated by dNTP but not significantly by TS primer. These data suggest that hTg contained in thyroid follicular cells of various thyroid diseases may affect the TA activity measured in biopsied thyroid specimens, and that the reduction of the TA activity by hTg may induce slow progression and growth, and low grade malignancy of thyroid cancer, particularly differentiated carcinoma.     

Subpopulations of cancer stem cells found in papillary thyroid carcinoma

Papillary thyroid carcinoma (PTC) is the most common form of thyroid cancer and while it has a generally good prognosis, tumor recurrence remains a major clinical challenge. Studying laboratory cell lines as well as clinical specimens indicate that PTC may follow the cancer stem cell (CSC) model. However, CSC characteristics relevant in PTC initiation and progression remain largely unknown. Here we studied a population of sphere-growing tumor cells isolated from primary cultures of clinical PTC. These sphere-growing cells consisted of aldehyde dehydrogenase positive (ALDH⁺) and ALDH negative (ALDH^-) cell subpopulations and demonstrated a hierarchical pattern of cell division. Using combinations of selective depletion, specific inhibition and cell sorting, we found that both subpopulations of the sphere cells were able to self-renew and initiate xenograft tumors independently, and fulfilled the definition of CSC. Importantly, when the subpopulations functioned together, the cancer-initiation efficiency and the xenograft tumor progression were significantly enhanced compared to either subpopulation alone. These data revealed crucial roles of ALDH^- CSC in PTC biology and suggested that CSC subpopulations function cooperatively to control PTC initiation and progression. Together, our study indicates that CSC subpopulations isolated from clinical specimens offer unprecedented opportunities for investigating PTC pathogenesis and developing effective therapies.     

Pituitary metastasis of follicular thyroid carcinoma

OBJECTIVE: The case of a 60-year-old male patient with follicular thyroid cancer who developed a pituitary mass proved to be a metastasis from thyroid cancer. METHODS: Assessment with whole-body scan, ultrasound, computed tomography and thyroglobulin measurements. RESULTS: Despite surgery and repeated doses of radioiodine, the patient developed diplopia and ptosis of the right eyelid, along with increasing thyroglobulin levels. A pituitary mass was discovered, with no signs of pituitary deficiency. The mass was removed and found to consist of neoplastic cells immunohistochemically positive to thyroglobulin. CONCLUSIONS: Distant metastases may develop in cases of follicular thyroid carcinoma, even after repeated doses of (131)I. Metastatic follicular thyroid carcinoma to the pituitary is a rare entity.     

Characterizing the three-dimensional organization of telomeres in papillary thyroid carcinoma cells

The relationship between the three-dimensional (3D) nuclear telomere architecture and specific genetic alterations in papillary thyroid carcinoma (PTC), in particular in cancer stem-like cells (CSLCs), has not yet been investigated. We isolated thyrospheres containing CSLCs from B-CPAP, K1, and TPC-1 PTC-derived cell lines, representative of tumors with different genetic backgrounds within the newly identified BRAF^V600E-like PTC subgroup, and used immortalized normal human thyrocytes (Nthy-ori 3.1) as control. We performed quantitative fluorescence in situ hybridization, 3D imaging, and 3D telomere analysis using TeloView software to examine telomere dysfunction in both parental and thyrosphere cells. Among the 3D telomere profile, a wide heterogeneity was observed, except for telomere intensity. Our findings indicate that CSLCs of each cell line had longer telomeres than parental cells, according to telomere intensity values, which correlate with telomere length. Indeed, the thyrosphere cells had lower numbers of lower-intensity telomeres (≤5,000 arbitrary fluorescent units, a.u.), compared with parental cancer cells, as well as parental control cells, (p < 0.0001). The B-CPAP thyrospheres showed a decreased number of higher intensity telomeres (>17,000 a.u.) than K1 and TPC-1 cells, as well as control cells (p < 0.0001). By selecting PTC-derived cell lines with different genetic backgrounds characteristic of BRAF^V600E-like PTC subgroups, we demonstrate that thyrosphere cells with BRAF^V600E and TP53 mutations show shorter telomeres than those harboring RET/PTC or BRAF^V600Eand wild-type TP53. Hence, our data reveal a trend towards a decrease in telomere shortening in CSLCs, representing the early cancer-promoting subpopulation, as opposed to parental cells representing the tumor bulk cells.     

Adenoid cystic pattern in follicular variant of papillary thyroid carcinoma: a report of four cases

S. Mandal, and S. Jain
Adenoid cystic pattern in follicular variant of papillary thyroid carcinoma: a report of four cases Objective: An adenoid cystic pattern in thyroid tumours is a rare finding that may be seen in papillary carcinoma of thyroid (PCT), the follicular variant of PCT (FV‐PCT), a rare cribriform‐morular variant of papillary carcinoma of thyroid (CMV‐PCT) and follicular carcinoma. There is little published cytological literature describing these patterns. We report four cases of PCT with this unusual pattern. Methods: Fine needle aspiration (FNA) cytology was performed on four patients with a neck lump using a 22‐G needle; smears were stained with Giemsa and Papanicolaou stains. Immunocytochemical staining for thyroglobulin was done in all cases. Results: The patients were female and ranged in age from 18 to 46 years. They presented with a gradually increasing mass in the neck. FNA smears in all cases showed nuclear features of PCT. There were also prominent follicular areas with hyaline globules in some of the cell clusters reminiscent of adenoid cystic carcinoma and, in places, morula‐like groups of neoplastic cells were also seen. Immunocytochemistry for thyroglobulin was positive in all cases but negative in the hyaline globules. Conclusions: Adenoid cystic areas with morula‐like groups in PCT are a rare finding. Cytopathologists and clinicians should be aware of these distinct features in thyroid tumours to avoid diagnosing metastatic adenoid cystic carcinoma. It is also important to rule out CMV‐PCT since that variant is mostly associated with familial adenomatous polyposis, although sporadic occurrence is known.     

Synergic radiosensitization of sinomenine hydrochloride and radioiodine on human papillary thyroid carcinoma cells

Radioiodine (¹³¹I) therapy is an important treatment for thyroid carcinoma. The response to radiotherapy sometimes limited by the development of radioresistance. Sinomenine hydrochloride(SH), was reported as a prospective radiosensitizer. This study was aim to evaluate synergic radiosensitization of SH and ¹³¹I on papillary thyroid carcinoma (PTC). We evaluated HTori-3, BCPAP and TPC-1 cells, the cell viability was evaluated by MTT. The experiment was divided into 4 groups: control group, SH (0.8 mM) group, I (¹³¹I 14.8 MBq/ml) group and ISH (SH 0.8 mM plus ¹³¹I 14.8 MBq/ml) group. Flow cytometry was used to investigate cell cycle phases and cell apoptosis. RT-PCR and western blotting were performed to determine the molecular changes. Compared to control group, SH significantly increased apoptosis and enhanced radiosensitivity of HTori-3 and PTC cells were related to the ratio of Bcl-2 to Bax protein downregulation and Fas, p21, p-ATM, p-Chk1, p-Chk2 and p53 protein expression upregulation in the ISH group (P < 0.05). Our results indicate that synergic radiosensitization of SH and iodine-131 on PTC cells and SH could be a potential therapeutic radiosensitizer in PTC radio therapy after total thyroidectomy.     

TSH compensates thyroid-specific IGF-I receptor knockout and causes papillary thyroid hyperplasia

Although TSH stimulates all aspects of thyroid physiology IGF-I signaling through a tyrosine kinase-containing transmembrane receptor exhibits a permissive impact on TSH action. To better understand the importance of the IGF-I receptor in the thyroid in vivo, we inactivated the Igf1r with a Tg promoter-driven Cre-lox system in mice. We studied male and female mice with thyroidal wild-type, Igf1r(+/-), and Igf1r(-/-) genotypes. Targeted Igf1r inactivation did transiently reduce thyroid hormone levels and significantly increased TSH levels in both heterozygous and homozygous mice without affecting thyroid weight. Histological analysis of thyroid tissue with Igf1r inactivation revealed hyperplasia and heterogeneous follicle structure. From 4 months of age, we detected papillary thyroid architecture in heterozygous and homozygous mice. We also noted increased body weight of male mice with a homozygous thyroidal null mutation in the Igf1r locus, compared with wild-type mice, respectively. A decrease of mRNA and protein for thyroid peroxidase and increased mRNA and protein for IGF-II receptor but no significant mRNA changes for the insulin receptor, the TSH receptor, and the sodium-iodide-symporter in both Igf1r(+/-) and Igf1r(-/-) mice were detected. Our results suggest that the strong increase of TSH benefits papillary thyroid hyperplasia and completely compensates the loss of IGF-I receptor signaling at the level of thyroid hormones without significant increase in thyroid weight. This could indicate that the IGF-I receptor signaling is less essential for thyroid hormone synthesis but maintains homeostasis and normal thyroid morphogenesis.     

Fine needle aspiration of follicular variant of papillary thyroid carcinoma presenting with pleural effusion: a case report

BACKGROUND: Malignant pleural effusion in association with mesothelioma, bronchogenic carcinoma and breast carcinoma is common, although less frequently reported with other malignancies. We report a follicular variant of papillary thyroid carcinoma (FVPTC), diagnosed on fine needle aspiration cytology (FNAC) of thyroid and lymph nodes and subsequently proved to have metastasized to the pleural cavity. CASE: A 46-year-old man presented with history of breathlessness, thyroid swelling, pleural effusion and bilateral cervical lymphadenopathy. FNAC of the thyroid swelling and the lymph nodes showed features of FVPTC with cervical lymph node metastasis. Pleural fluid examination led to suspicion of pleural involvement by metastatic deposit, confirmed by subsequent pleural biopsy. CONCLUSION: Thyroid malignancies presenting with pleural effusion are rare. In this case, although pleural fluid cytology suggested involvement of pleura, a definitive diagnosis could be rendered only on pleural biopsy. An ancillary aid, such as immunocytochemistry, could have helped establish pleural involvement on routine pleural fluid cytology alone. This case emphasizes the possible existence of rare cases of FVPTC that may be associated with a dismal prognosis. In our case, initial diagnosis of FVPTC could be made only on correlating FNA features of thyroid aspirate with those of lymph node aspirate.     

MIB-1 immunohistometry of follicular adenoma and follicular carcinoma of the thyroid gland

OBJECTIVE: To analyze cellular proliferative activity, MIB-1 immunopositivity of normal tissue (n = 20), follicular adenoma (n = 30) and follicular carcinoma (n = 32) of the thyroid gland was analyzed by means of immunohistometry. STUDY DESIGN: Immunohistochemical reactions were performed on 3-micron sections from routinely formalin fixed and paraffin embedded surgical specimens using an indirect peroxidase method. The rate of immunostained cells was determined using the CM-2 TV image analysis system (Hund, Wetzlar, Federal Republic of Germany). Forty viewing fields (1.94 mm2) were measured with 20:1 objective magnification. An average of 5,965 cells were assessed in each case. RESULTS: Mean MIB-1 immunopositivity was higher in follicular carcinoma (average, 2.30%) and follicular adenoma (0.58%) than in normal thyroid tissue (0.14%). The distribution of single values differed significantly between groups (P < .001). To test the suitability of MIB-1 immunohistometry for the differential diagnosis of follicular adenoma and follicular carcinoma, different four-field tables with varying thresholds were calculated. Using a threshold of 0.9%, follicular carcinoma could be detected with a sensitivity of 75% (24/32) and a specificity of 83% (25/30). If a specificity of 90% is required (27/30), the sensitivity of the test decreases to 69% (22/32), based on a threshold of 1.1%. CONCLUSION: As some overlap of single values has to be considered, MIB-1 immunohistometry, although presenting new insights into the proliferative potential of thyroid lesions, is of only limited value for the differential diagnosis of follicular lesions in routine surgical pathology.