The Diagnostic Value of Calcitonin Measurement in Wash-out Fluid from Fine-Needle Aspiration of Thyroid Nodules in the Diagnosis of Medullary Thyroid Cancer

ObjectiveThe diagnostic value of calcitonin measurement in fine-needle aspiration biopsy (FNAB) washout fluid (Ct-FNAB) for medullary thyroid cancer (MTC) remains to be determined. This prospective study aimed to assess the diagnostic value of Ct-FNAB in thyroid nodules in comparison with basal serum calcitonin (Ct), pentagas- trin-stimulated Ct (Pg-sCt), and cytology.MethodsAmong patients with goiter addressed with US-FNAB who had an initial clinical suggestion for thyroidectomy, 27 patients with thyroid nodule/s (n = 60) and normal, borderline, or increased Ct fulfilled the criteria for thyroidectomy. All 27 patients (enrolled according to exclusion/inclusion criteria) underwent ultrasonography (US), Ct, Pg-sCt, US-assisted FNAB of each patient’s nodule for both cytology, and Ct-FNAB before thyroidectomy.ResultsCt-FNAB always resulted in >1,000 pg/mL in MTC nodules at histology. For values between 36 and pg/mL, MTCs and nodular or micronodular C-cell hyperplasia (CCH) results overlapped. Most of the nodules without MTC and/or CCH had Ct-FNAB <17 pg/mL. Ct-FNAB diagnostic power was superior to and similar to other diagnostic procedures (Ct, Pg-sCt, and cytology) in identifying both MTC and CCH, and MTC alone, respectively.ConclusionThe diagnostic power of Ct-FNAB is valuable compared with other routine procedures. Ct-FNAB is highly reliable for the early detection and accurate localization of MTC in thyroid nodules, but it does not differentiate between MTC and CCH. Ct-FNAB is an extremely valuable diagnostic tool, especially considering that other diagnostic procedures do not provide a definitive diagnosis, and it can be included in the clinical work-up of thyroid nodules when MTC is suspected. (Endocr Pract. 2013;19:769-779)     

Unusual Case of Multiple Endocrine Neoplasia Type 2A Syndrome Without Medullary Thyroid Carcinoma

ObjectiveTo present an unusual case of multiple endocrine neoplasia type 2A (MEN 2A) syndrome and to describe how this case differs from the typical clinical features and usual genetic variations seen in classic MEN 2A syndrome.MethodsWe describe the work-up, diagnosis, and treatment course of a patient who presented with multifocal pheochromocytomas, parathyroid adenoma, thyroid abnormalities, and a RET mutation.ResultsA 65-year-old man with previously treated pheochromocytoma presented with a parathyroid adenoma, multiple thyroid nodules, and a RET polymorphism. C-cell hyperplasia (CCH) or medullary thyroid carcinoma (MTC) occurs with nearly 100% penetrance in patients with MEN 2A syndrome. Our patient did not have CCH or frank MTC, but he expressed the other manifestations of the MEN 2A syndrome.ConclusionMEN 2A syndrome is characterized by the occurrence of MTC, pheochromocytomas, and parathyroid hyperplasia or adenomas. It is inherited in an autosomal dominant fashion, and more than 80% of patients with MEN 2A have a specific substitution on codon 634 of the RET proto-oncogene. Despite the nearly 100% penetrance of MTC or CCH in patients with MEN 2A, our patient did not have this. Additionally, he exhibited a RET mutation that is uncommonly seen in classic MEN 2A syndrome. Our patient may have a MEN 2A variant or a pseudo-MEN 2A syndrome. (Endocr Pract. 2011;17:e4-e7)     

Predictive Value of Calcium Test for Preoperative Diagnosis of Medullary Thyroid Carcinoma in Patients With Moderately Elevated Basal Calcitonin

ObjectiveMedullary thyroid carcinoma (MTC) can be very aggressive, and early diagnosis is based on routine measurement of serum calcitonin (CT) and RET genetic testing for hereditary forms. Basal serum CT (bCT) concentrations are useful in the early detection of MTC, although it is still unclear whether they can also be used for the differential diagnosis between MTC and C-cell hyperplasia (CCH). Since false-positive results can be obtained with the basal measurement of CT, a provocative test to evaluate stimulated CT (sCT) is often needed. The objective of this study was to investigate the utility of a calcium gluconate test for CT in distinguishing MTC from CCH, a precancerous condition in hereditary forms of MTCs but with unclear significance in sporadic MTCs.MethodsA total of 74 patients underwent the calcium loading test before thyroidectomy, and bCT and sCT levels were compared with histologic results by receiver operating characteristic plot analyses.ResultsA peak CT level of 388.4 pg/mL after stimulation with calcium gluconate was able to significantly distinguish patients with MTC from those with CCH and those without C-cell pathology, with 81.8% sensitivity and 36.5% specificity. A bCT level of 16.1 pg/mL was able to distinguish between these 2 groups of patients with a sensitivity of 90%.ConclusionHigh-dose calcium test is an effective procedure that can be applied for differential diagnosis of MTC and CCH. Reference ranges for calcium sCT levels and CT thresholds in different groups of patients have been identified.     

Occult medullary carcinoma of thyroid with lymph node metastases: a case report

BACKGROUND: Occult thyroid malignancies presenting with secondary neck masses as the first clinical manifestation is well known. Although rare, medullary carcinoma serves a potential source for lymph node metastases. The characteristic cytomorphology of medullary thyroid carcinoma (MTC) should clinch the diagnosis. Further, fine needle aspiration cytology (FNAC) of the ultrasonography-detected occult nodules in thyroid serves as a useful preoperative diagnostic tool. CASE: A 22-year-old man presented with left-sided neck masses of 1 year duration. FNAC smears of the neck masses revealed cytomorphology characteristic of MTC. Ultrasonography of the thyroid led to ruling out the presence of an occult nodule and detected an 8-mm nodule in the left thyroid lobe. Ultrasound-guided FNAC of the nodule showed features similar to those with FNAC of the neck masses. Surgical resection of thyroid and neck masses further confirmed the diagnosis of a primary occult MTC with lymph node metastases. CONCLUSION: FNAC smears of lymph node masses showing the distinct cytomorphology of MTC should prompt suspicion for occult primary in thyroid. Ultrasound-guided FNAC of these occult nodules, if detected, further serves a diagnostic tool for accurate preoperative diagnosis when metastasis presents as the first clinical manifestation of an occult primary.     

Genetic alterations in medullary thyroid cancer: diagnostic and prognostic markers

Medullary thyroid carcinoma (MTC) is a rare calcitonin producing neuroendocrine tumour that originates from the parafollicular C-cells of the thyroid gland. The RET proto-oncogene encodes the RET receptor tyrosine kinase, with consequently essential roles in cell survival, differentiation and proliferation. Somatic or germline mutations of the RET gene play an important role in this neoplasm in development of sporadic and familial forms, respectively. Genetic diagnosis has an important role in differentiating sporadic from familiar MTC. Furthermore, depending on the location of the mutation, patients can be classified into risk classes. Therefore, genetic screening of the RET gene plays a critical role not only in diagnosis but also in assessing the prognosis and course of MTC.     

Aromatase excess syndrome presenting with prepubertal gynecomastia in an Egyptian child with type 1 neurofibromatosis

A romatase excess syndrome (AEXS) is a rare autosomal dominant disorder characterized by prepubertal gynecomastia, it responds well to medical treatment. In the absence of prompt suspicion, it can expose the patient to the risk of unnecessary surgical intervention. Up to our best knowledge, the association between AEXS and neurofibromatosis type 1 (NF1) was not reported before. Here, we describe a AEXS presenting with prepubertal gynecomastia in an Egyptian child with NF1 that improved with aromatase inhibitors.     

Gene expression profile of medullary thyroid carcinoma--preliminary results

INTRODUCTION: Medullary thyroid carcinoma occurs both as a sporadic and a familial disease. Inherited MTC (iMTC) patients usually exhibit better prognosis than patients with sporadic form of MTC (sMTC), however, in both subtypes the outcome is unpredictable. No molecular markers contributing to the prognosis or predicting the type of therapy have been introduced to clinical practice until now. The aim of this study was to analyze gene expression pattern of MTC by high density oligonucleotide microarray. MATERIAL AND METHODS: 24 samples were studied: 12 MTC and 12 corresponding normal tissues, (Affymetrix HG-U 133A). Among MTC patients there were half inherited cases and half sporadic ones. RESULTS: First, the differences between MTC and thyroid tissue were analyzed by Singular Value Decomposition (SVD) which indicated three main modes determining the variability of gene expression profile: the first two were related to the tumor/normal tissue difference and the third one was related to the immune response. The characteristic expression pattern, beside of numerous changes within cancer- related genes, included many up-regulated genes specific for thyroid C cells. Further analysis of the second component revealed two subgroups of MTC, but the subdivision was not related to the iMTC/sMTC difference. Recursive Feature Replacement (RFR) confirmed the very similar expression profile in both forms of MTC. With subsequent ANOVA analysis some genes with differential expression could be specified, among them monoamine oxidase B (MAOB) and gamma-aminobutyric acid receptor (GABRR1) which were consistently up-regulated in sMTC. In contrary, some genes involved in regulation of cell proliferation: opioid growth factor receptor(OGFR) and synaptotagmin V (SYT 5) were up-regulated in iMTC. CONCLUSIONS: The obtained data indicate a very similar gene expression pattern in inherited and sporadic MTC. Minor differences in their molecular profile require further analysis.     

甲状腺髓样癌超声弹性成像定量参数与病灶组织中降钙素原的相关性研究

摘要 目的：探讨甲状腺髓样癌（MTC）超声弹性成像定量参数与病灶组织中降钙素原（PCT）的相关性。方法：回顾性选取2017年2月-2021年8月于我院行甲状腺癌手术且术后病理诊断为MTC的患者32例作为研究组,随机选择同期于我院行甲状腺良性肿瘤手术的患者40例作为对照组,所有患者均进行超声弹性成像检查。收集所有患者术后MTC和甲状腺良性肿瘤组织,采用免疫组化法检测MTC和甲状腺良性肿瘤组织中PCT的阳性表达率。采用受试者工作特征（ROC）曲线分析应变率比值对MTC和甲状腺良性肿瘤的鉴别诊断价值。采用Pearson相关分析应变率比值与病灶组织中PCT阳性表达率的相关性。结果：研究组应变率比值明显高于对照组,差异有统计学意义（P<0.05）。MTC组织中PCT阳性表达率为71.88%（23/32）高于甲状腺良性肿瘤组织中的35.00%（14/40）,差异有统计学意义（P<0.05）。经ROC曲线分析发现应变率比值鉴别诊断MTC和甲状腺良性肿瘤的最佳截断值为3.30,曲线下面积为0.761。Pearson相关分析显示应变率比值与MTC组织中PCT阳性表达率呈正相关（P<0.05）。结论：MTC超声弹性成像应变率比值与病灶组织中PCT阳性表达率呈正相关,且应变率比值对MTC具有一定的诊断价值。     

Familial medullary thyroid carcinoma and multiple endocrine neoplasia type 2B map to the same region of chromosome 10 as multiple endocrine neoplasia type 2A.

Medullary thyroid carcinoma (MTC) occurs as a component of three well-described autosomal dominant familial cancer syndromes. Multiple endocrine neoplasia type 2A (MEN 2A) is characterized by MTC, pheochromocytomas, and parathyroid hyperplasia. Patients with the rarer multiple endocrine neoplasia type 2B (MEN 2B) syndrome develop MTC and pheochromocytomas, as well as mucosal neuromas, ganglioneuromatosis of the gastrointestinal tract, and a characteristic "marfanoid" habitus. Finally, MTC is transmitted in an autosomal dominant pattern in some families without associated pheochromocytomas or parathyroid hyperplasia (familial medullary thyroid carcinoma, MTC1(2). Sixty-one members of two well-characterized kindreds segregating MTC1 and 34 [corrected] members of six families segregating MEN2B were genotyped using a panel of RFLP probes from the pericentromeric region of chromosome 10 near a locus for MEN 2A. Statistically significant linkage was observed between the chromosome 10 centromere-specific marker D10Z1 and MTC1 (maximum pairwise lod score 5.88 with 0% recombination) and D10Z1 and MEN2B (maximum pairwise lod score 3.58 with 0% recombination). A maximum multipoint lod score of 4.08 was obtained for MEN2B at the position of D10Z1. In addition, 92 members of a previously unreported large MEN2A kindred were genotyped, and linkage to the pericentromeric region of chromosome 10 is reported (maximum pairwise lod score of 11.33 with 0% recombination between MEN2A and RBP3). These results demonstrate that both a locus for familial MTC and a locus for MEN 2B map to the pericentromeric region of chromosome 10, in the same region as a locus for MEN 2A. The finding that each of these three clinically distinct familial cancer syndromes maps to the same chromosomal region suggests that all are allelic mutations at the same locus or represent a cluster of genes involved in the regulation of neuroendocrine tissue development.     

Indomethacin inhibits cell growth of medullary thyroid carcinoma by reducing cell cycle progression into S phase

Indomethacin, a non-steroidal anti-inflammatory drug (NSAID), has been reported to inhibit the growth of medullary thyroid carcinoma (MTC) cells in vitro. However, the mechanism of inhibition of MTC cell growth by indomethacin and its potency have yet to be revealed. We examined the effect of indomethacin on three different MTC cell lines (TT cells, DRO 81-1 cells and HRO 85-1 cells) and two non-MTC cells. The mechanism of indomethacin action in MTC cells was investigated by analyzing intracellular prostaglandin level, apoptosis, and cell cycle in TT cells. Indomethacin inhibited cell growth of all three MTC cell lines but not normal thyroid cells or anaplastic thyroid carcinoma cells. Indomethacin at 10 microM or greater showed a dose response inhibition of cell growth. Indomethacin at 25 muM, a putative therapeutic serum indomethacin level, showed potency similar to 100 to 200 nM sunitinib, a receptor tyrosine kinase inhibitor. To examine whether prostaglandin depletion might determine the inhibition of MTC cell growth, we created different prostaglandin E2 (PGE2) levels in TT cells using three different NSAIDs. A profound PGE2 depletion by indomethacin-ester, a potent cyclooxygenase (COX) II inhibitor, showed the least inhibition of cell growth. Indomethacin did not increase apoptosis of TT cells. Indomethacin, but not naproxen or indomethacin-ester, reduced cell cycle progression into S phase; this was unrelated to the degree of PGE2 depletion. The expression of phosphorylated retinoblastoma (pRb) protein that shifts cells from G(1) to S phase was reduced after exposure to indomethacin. In conclusion, indomethacin has specific anti-tumor effect on MTC cells, probably by reducing cell cycle progression into S phase rather than by prostaglandin depletion. Since no drug therapy is currently available for MTC, indomethacin may be one of the therapeutic candidates.     

青岛地区某医院12年甲状腺癌发病模式变迁

目的:探讨青岛地区某医院12年甲状腺癌的发病趋势和病理类型分布。方法:回顾性分析2001-2012年于青岛大学附属医院行手术切除的甲状腺癌患者的发病年龄、性别比例、手术数量以及病理类型构成比的变化。结果:12年来手术治疗甲状腺癌2421例,其中乳头状癌(PTC)占94.13%,滤泡状癌(FTC)占3.02%,髓样癌(MTC)占2.15%,未分化癌(ATC)占0.70%。甲状腺癌手术数量呈逐年递增趋势,尤以近4年升高显著,其病理类型以PTC为主,构成比例由79.63%上升至97.47%。四类甲状腺癌均以女性多见(男女比例1:1.38-1:4.37)。甲状腺癌的平均确诊年龄为46.80岁,PTC最低(46.48岁),ATC最高(64.25岁)。结论:青岛地区甲状腺癌发病数量呈逐年递增趋势,PTC是最常见的病理类型,其构成比例上升明显,其他类型相对下降。PTC的发病可能与高碘有关。     

Medullary Thyroid Carcinoma

ObjectiveThis review outlines advances in the diagnosis, genetic testing, and progress in medullary thyroid cancer (MTC) treatment in light of the most recent evidence.MethodsEnglish-language articles pertaining to MTC published up to 2012 were reviewed. The pertinent articles and their references were obtained and those considered relevant were reviewed for inclusion.ResultsMTC is an uncommon neuroendocrine malignancy that accounts for 5% of thyroid cancers. MTC presents in sporadic and familial forms (multiple endocrine neoplasia [MEN] 2A, MEN 2B, or familial MTC syndromes). The familial forms are secondary to germline mutations in the REarranged during Transfection (RET) proto-oncogene. Early diagnosis and treatment is paramount. Genetic testing has made possible early detection in asymptomatic carriers and high-risk patients, with early or prophylactic surgery being curative in many. All carriers of an RET mutation should be evaluated and treated surgically for MTC. The primary treatment in all patients diagnosed with MTC is total thyroidectomy with central lymph node dissection. Calcitonin and carcinoembryonic antigen levels can be used as prognostic factors and as tumor markers. If elevated, further investigation, including use of imaging modalities, may be necessary for evaluation of metastatic disease. Surgery remains the main treatment for local and locally advanced disease.ConclusionMTC is rare, but morbidity and mortality remain high if untreated. Genetic testing should be offered to all patients. Treatment of choice remains total thyroid-ectomy and central lymph node dissection. Palliative treatment for advanced disease includes surgery, radiation, standard chemotherapy, chemoembolization and more recently, targeted therapies (tyrosine kinase inhibitors). (Endocr Pract. 2013;19:703-711)     

A familial case of multiple endocrine neoplasia (MEN IIb). Diagnosis of medullary thyroid cancer

The familial observations of multiple endocrine neoplasia are rare such that there are only four known cases in France. In our family, two children and their mother are affected. Their mother, at the age of 16, was operated on a medullary thyroid cancer (MTC) and now presents with a phaeochromocytoma. Vanessa also presents with a MTC but without either phaeochromocytoma nor hyperparathyroidism. Her sister was then systematically screened and the only positive test was Pentagastrin. This allowed us to practice a thyroidectomy which will confirm the presence of a medullary thyroid cancer. In all three cases, the Marfan-like features, the abnormal facies and lingual neuromas are all features of the disease. These observations are of interest for the systemic familial screening of MTC by tumour markers (calcitonin, ACE) and by the Pentagastrin test, while awaiting for the use of specific probes on chromosome 10.     

Uptake of 131I-metaiodobenzylguanidine by 6-23 rat medullary thyroid carcinoma

Uptake of 131iodine-metaiodobenzylguanidine (131I-MIBG) by 6-23 rat medullary thyroid carcinoma (MTC), was studied in vitro and in vivo. In vitro, there was an 8-fold increase in 131I uptake by 6-23 cells when labeled with 131I-MIBG (131I 24 +/- 15 cpm/10(6) cells, 131I-MIBG 196 +/- 9 cpm/10(6) cells). MIBG uptake in vitro was the same at 4 degrees C and 37 degrees C. In contrast, 131I-MIBG uptake by PC-12 rat pheochromocytoma cells were 200 times greater (131I-MIBG 42,412 +/- 6,755 cpm/10(6) cells). 131I-MIBG uptake by rat MTC cells in vitro were of a comparable magnitude to the uptake of 131I-MIBG by rat ileal enterochromaffin cells (RIE-1) and mouse colon cancer cells (MC-26). In vivo, uptake of 131I-MIBG by 6-23 MTC tumor was considerably less than in the normal tissues (muscle, liver, spleen, kidney, adrenal and thyroid). Gamma camera studies of 131I-MIBG uptake by 6-23 MTC tumors growing in Wag-Rij rats were only transiently positive in 1 out of 4 rats studied. We conclude that 131I-MIBG is poorly taken up by rat medullary thyroid carcinoma and is an unpredictable marker for localization of rat MTC.     

ProGRP as a Novel Biomarker for the Differential Diagnosis of Medullary Thyroid Carcinoma in Patients with Thyroid Nodules

Objective: To investigate the release of progastrin-releasing peptide (ProGRP) in patients with thyroid nodules and the value of ProGRP in fine-needle aspirate washout fluid (FNA-ProGRP) in the differential diagnosis between medullary thyroid carcinoma (MTC) and non-MTC thyroid nodules.Methods: We investigated 2,446 healthy persons and 212 patients with 235 thyroid nodules. They were classified into healthy, nodular goiter, chronic thyroiditis, thyroid follicular neoplasm, papillary thyroid carcinoma, follicular thyroid carcinoma, and medullary thyroid carcinoma. The serum ProGRP and FNA-ProGRP were measured.Results: The serum ProGRP median concentration in MTC was 124.40 pg/mL, significantly higher than in other groups. The cutoff value of serum ProGRP was 68.30 pg/mL, leading to 53.85% sensitivity, 96.98% specificity, and 0.51 kappa value in MTC. The FNA-ProGRP median concentration in MTC nodules was 2,096.00 pg/mL, significantly higher than in other groups. A receiver operating characteristic analysis of MTC nodules and non-MTC nodules indicated that the cutoff value was 22.77 pg/mL, leading to 94.12% sensitivity, 98.27% specificity, and 0.85 kappa value.Conclusion: FNA-ProGRP measurement could be served as an ancillary method for the differential diagnosis between MTC and non-MTC thyroid nodules.Abbreviations: CEA = carcinoembryonic antigen; CT = calcitonin; FNAC = fine-needle aspiration cytology; FNA-CT = calcitonin in fine-needle aspirate washout fluid; FNA-ProGRP = ProGRP in fine-needle aspirate washout fluid; MTC = medullary thyroid carcinoma; ProGRP = progastrin-releasing peptide; SCLC = small-cell lung cancer; TM = tumor marker     

Medullar thyroid carcinoma in mediastinum initially presenting as Ectopic ACTH syndrome. A case report

A rare case with ectopic adrenocorticotrophic hormone syndrome (EAS) caused by medullar thyroid carcinoma (MTC) in mediastinum was reported. This 49 year-old male patient initially presented with serious and intractable hypokalemia. Endocrine evaluations showed increased levels of adrenocorticotrophic hormone (ACTH) and urinary free cortisol, which could not be suppressed more than 50% by high-dose dexamethasone suppression test. Computed tomography (CT) scan detected a 5×5×5?cm mass at the bottom of thyroid in anterior mediastinum. The patient underwent total thyroidectomy with central compartment and ipsilateral modified radical neck dissection. Pathological examination showed an infiltrating thyroid medullary carcinoma with abundant amyloid deposition, meanwhile immunohistochemical positive for ACTH. After surgery, serum levels of kalium, as well as cortisol and ACTH returned to normal range. During follow-up, the patient's clinical manifestation of Cushing syndrome relieved.     

The genetic background of medullary thyroid carcinoma in young patients

The study was undertaken to evaluate the frequency of RET polymorphisms at codons 769 and 836 in young medullary thyroid carcinoma (MTC) patients in whom the presence of a known germline mutation has been excluded. 40 patients aged 10-29 were subjected to genetic analysis of RET exons 10, 11, 13, 14 and 16 and compared to 140 older patients. The hereditary component occurred to be very high in young MTC patients: 57% carry the germline mutation, other 28% exhibit at least one rare polymorphic variant of RET. The observed allelic frequencies were 38% for polymorphic variant L769CTG and 6% for variant S836AGT. The results were significantly higher than those obtained in the group of older patients: 20% and 1% for L769CTG and S836AGT, respectively. Our results speak in favour that the polymorphism in RET codon 769 and 836 may also be a factor predisposing to the development of MTC in young age.     

Fine needle aspiration cytology of medullary thyroid carcinoma: a review of 18 cases

A series of 18 consecutive medullary thyroid carcinomas (MTC) diagnosed by fine needle aspiration cytology (FNAC) is described. The most important diagnostic cytologic criteria were the dispersed cell pattern, the polygonal appearance of the cells, binucleated cells and the presence of amyloid. Other less common cytologic features are reported and the variable microscopic appearance of MTC is pointed out. The possibility that this cytologic variability of MTC may be by itself an important diagnostic feature is proposed.     

Medullary thyroid carcinoma in a child with a new RET mutation and a RET polymorphism

We report a 12 year old boy with an isolated medullary thyroid carcinoma (MTC). A mutation analysis of the RET-proto-oncogene in this boy showed an in frame insertion-deletion mutation (insTTCTdelG) at codon 666 of the RET proto-oncogene. This RET mutation has not been reported previously. The boy's mother and his 82-year-old maternal grandfather showed the same mutation. None of the two ever showed symptoms of MTC. The mother underwent a preventive total thyroidectomy and pathological examination showed C-cell hyperplasia and early MTC. Further genetic analysis showed that the boy inherited a well-known coding polymorphism in exon 11 (G691S) from his father. Therefore the boy is a compound heterozygote for the insertion-deletion mutation at codon 666 and the G691S polymorphism in the RET gene. We hypothesize that the insTTCTdelG mutation at codon 666 is associated with low penetrance for MTC and that the young age of MTC in the reported child results most likely from the additive effects of both mutations (insTTCTdelG and G691S).