Thyroid follicular renal cell carcinoma excluding thyroid metastases: A case report

lNTRODUCTlON

Renal cell carcinoma (RCC) is a malignant tumour that originates from the renal parenchymal urothelial system and accounts for approximately 80%-85% of all malignant renal tumours. It is one of the most common tumours in the urinary system, second only to prostate cancer and bladder cancer[1]. Thyroid follicular RCC (TFRCC) is a rare new subtype of primary RCC that is not a true carcinoma originating from the thyroid gland. Although it is histologically similar to thyroid follicular carcinoma, TFRCC lacks typical thyroid markers. The rarity of these tumours limits our understanding of them, leading to misdiagnosis and inappropriate treatment. Here, we report the case of a 60-year-old man who presented with lower back and abdominal pain. Imaging examination revealed lesions in the right kidney and bilateral thyroid gland. Based on postoperative pathological examination findings, renal metastasis of the thyroid carcinoma was excluded.

在翻轉(zhuǎn)課堂教學(xué)中，學(xué)生課堂知識(shí)的吸收和內(nèi)化環(huán)節(jié)上，學(xué)習(xí)自主權(quán)交給學(xué)生，自主決定學(xué)習(xí)的時(shí)間，學(xué)習(xí)的方法和策略，學(xué)習(xí)者自主確定學(xué)習(xí)內(nèi)容和方式，監(jiān)控和評(píng)價(jià)學(xué)習(xí)過程；同時(shí)，在教學(xué)中，學(xué)生通過合作互助小組，相互交流討論，解決學(xué)習(xí)中的難點(diǎn)，獲得對(duì)知識(shí)點(diǎn)的理解，增強(qiáng)學(xué)生團(tuán)隊(duì)協(xié)作意識(shí)提升協(xié)作學(xué)習(xí)能力。

CASE PRESENTATlON

Chief complaints

二要建立健全工程質(zhì)量終身負(fù)責(zé)制，從嚴(yán)把好工程規(guī)劃、方案編制、施工管理、檢查驗(yàn)收等各個(gè)環(huán)節(jié)，強(qiáng)化科技支撐作用，加強(qiáng)技術(shù)指導(dǎo)，推行農(nóng)水工程標(biāo)準(zhǔn)化設(shè)計(jì)圖集，推進(jìn)專業(yè)化施工，確保工程質(zhì)量，并建立群眾義務(wù)監(jiān)督員等外部監(jiān)管制度。

History of present illness

TFRCC has a certain degree of invasiveness, up to T3, and can have retroperitoneal lymph node metastasis and distant metastasis such as skull and meninges[6]. These tumours may metastasise through the blood-derived pathway, but the degree of malignancy is generally low. Surgical resection is the main treatment, which is supplemented by postoperative follow-up. Surgical methods include radical nephrectomy, partial nephrectomy, and resection of the metastatic lesion, which can be performed even if distant metastasis occurs. Except for a few patients with dedifferentiation of sarcomatoid areas[18] or with highly malignant cells[8], there is currently no clear clinicopathological feature that can predict the occurrence of metastasis and its poor outcome. There are limited reports on adjuvant therapy after surgery. At present, surgery is selected according to the general guidelines for RCC, and its unique treatment scheme needs to be actively explored in clinical practice to avoid unnecessary over-treatment and ensure the quality of life of patients. Following effective treatment,patients do not easily relapse, have a good prognosis, and can achieve long-term survival.

History of past illness

The patient had a 10-year history of diabetes. He did not take his medicine regularly and had poor blood glucose control.

Personal and family history

The patient had no relevant personal or family history.

A 60-year-old man presented with a ＞ 1-mo history of right lower back and abdominal pain.

Physical examination

The patient’s vital signs were normal.

Laboratory examinations

Laboratory examinations on admission revealed a carbohydrate antigen 19-9 level of 99.98 μmol/mL and creatinine level of 73.5 μmol/L (postoperative creatinine level: 79.1 μmol/L). The glomerular filtration rate in the left and right kidneys was 34.88 and 34.89 mL/min, respectively.

Imaging examinations

Ultrasound showed a round hypoechoic mass measuring approximately 0.9 × 0.8 cm in the middle and lower parenchyma of the right kidney; however, there was no obvious blood flow signal in the mass.Computed tomography angiography revealed a small nodular iso-density shadow (approximately 1 cm in diameter) in the middle parenchyma of the right kidney that protruded to the edge of the kidney. An enhanced scan showed continuous and obvious enhancement during the arterial phase. However, the enhancement was not uniform, and there were no abnormal tumour-supplying blood vessels (Figure 1).Ultrasound of the thyroid gland performed in our hospital on 5 January 2021 showed bilateral thyroid nodules (TI-RADS3 class).

通過物理斜面模型與巖質(zhì)邊坡受力分析，發(fā)現(xiàn)高中物理模型受力分析與巖質(zhì)邊坡受力特征非常相似；尤其是邊坡滑動(dòng)時(shí)，物理斜面模型與巖質(zhì)邊坡受力特征一致，斜面摩擦力與巖質(zhì)邊坡下滑粘結(jié)力計(jì)算方法一致，所以巖質(zhì)邊坡受力特征可以用物理斜面模型代替；

FlNAL DlAGNOSlS

Postoperative pathology showed: Part of the renal tissue, 2.1 cm × 1.5 cm × 1.5 cm in size, had been cut in half in the clinic. Analysis of the tissue section revealed a nodular body measuring 1.2 cm × 1.0 cm ×0.6 cm; it was greyish-yellow or greyish white, slightly tough, and had slightly unclear boundaries.Moreover, it contained free adipose tissue (5.5 cm × 3.3 cm × 1.2 cm) and was not in contact with lymph nodes. Microscopy revealed glandular, cystic follicular, or papillary tumour cells of uniform size. The cytoplasm was medium stained, lightly stained, or empty bright, and the nucleus was round or slightly irregular with small nucleoli and red-stained lumen. Immunohistochemistry showed CK (3+); EMA) (+);Vimentin (+); PAX-8 (+); CK7 (+); Ki67 (2%+); P504S (+); E-cd (+); CD117 (-); CD10 (+); RCC (-);Calponin (-); TTF-1 (-); TG (-); TFE3 (weak+); S-100 (-); WT-1 (-); CA9 (-). Therefore, TFRCC of the right kidney was considered (Figure 2).

其次，從本地地方特色來看，我們高淳源遠(yuǎn)流長(zhǎng)的地方文化和特色就是我們應(yīng)該弘揚(yáng)的民族優(yōu)秀文化?！昂霌P(yáng)民族優(yōu)秀文化和吸收人類進(jìn)步文化”“引導(dǎo)學(xué)生重視語(yǔ)言的積累和感悟，接受優(yōu)秀文化的熏陶，提高思想品德修養(yǎng)和審美情趣，形成良好的個(gè)性、健全的人格，促進(jìn)職業(yè)生涯的發(fā)展”，中職語(yǔ)文教學(xué)應(yīng)成為弘揚(yáng)民族優(yōu)秀文化的陣地。

該軟件的部分功能涉及學(xué)生隱私，在當(dāng)前大學(xué)生對(duì)學(xué)生管理工作高度敏感的時(shí)代，需要給予他們一定的空間。比如定位功能的使用，學(xué)生比較在意行蹤的隱私性保護(hù)。因此，此功能若無(wú)限無(wú)度使用易造成學(xué)生的排斥心理。

TREATMENT

The pathological diagnosis should be differentiated from thyroid carcinoma with renal metastasis and ovarian monodermal teratoma with renal metastasis, and the history can not completely exclude the primary TFRCC. The immunohistochemical markers TTF-1 and TG have important value in differential diagnosis. However, in poorly differentiated or sarcomatoid-differentiated thyroid carcinoma, TG and TTF-1 are absent, which can be distinguished according to whether there is a primary tumour. In addition, attention should be paid to the differentiation with renal thyroidisation[11], other nephrogenic tumours[12], and atrophic kidney[15]. It is not difficult to distinguish them in combination with clinical and histological characteristics. Our patient had bilateral thyroid mass; therefore, we needed to rule out the possibility that the kidney lesion was metastasized by thyroid carcinoma. Thyroid cancer often metastasises to the bone, lung, and liver and rarely to the kidney. There are ＜30 reported cases of renal metastasis of thyroid cancer origin, and the expression of TTF-1 and TG is both positive and strongly positive[16,17]. The specimens from our patient were repeatedly examined by the Pathology Department in our hospital, and both TTF-1 and TG continued to be absent. Therefore, the possibility of thyroid origin was ruled out, and TFRCC was presumed to be the primary tumour in the kidney. Thediagnosis was then confirmed by thyroid tumour biopsy, similar to the method used in the case reported by Cai[16] and Tretiakova[13].

OUTCOME AND FOLLOW-UP

The patient underwent re-examination on 30 March 2021, and the CT scan showed that the right kidney had changed after partial nephrectomy, but there were no other abnormalities. At the last follow-up, the patient was alive and healthy.

DlSCUSSlON

Previously, TFRCC was known as thyroid-like follicular carcinoma of the kidney or thyroid follicular carcinoma-like renal tumour, a special type of RCC with thyroid follicular carcinoma-like histomorphology. This rare, new type of RCC was described in detail at the 2012 International Society of Urological Pathology. In 2016, the World Health Organization Classification of Urological Oncology reclassified renal tumour subtypes, and TFRCC was listed as a ‘tentative renal cell carcinoma’ due to its extremely low incidence rate and small number of cases available for review[2]. This type of tumour was first described by Angell[3] in 1996. Immunohistochemical staining of the reported cases showed positive expression of TG and TTF-1 in tumour cells, although no space-occupying lesions were detected by thyroid examination. However, considering that papillary thyroid carcinoma can develop lymph node or distant metastasis with very small primary foci, we believe that the first case of TFRCC was reported in an abstract published by Amin[4] in 2004 and in a case report published by Jung[5] in 2006. Thus far, approximately 41 cases have been reported[6].

Due to its rarity, the pathogenic factors of TFRCC are unclear. Recent studies have found that a previous history of malignant tumour and chemotherapy, especially the use of a platinum-based chemotherapy regimen, significantly increased the risk of TFRCC, but the relationship between the mutual development needs to be determined in future studies[7]. Moreover, relevant genetic data on TFRCC are limited. In only a few groups of genetic tests, there were obvious genetic changes in TFRCC,but the chromosomal changes were significantly different to each other, and the genetic changes were not consistent with those of other known types of RCC[8]. More cases and studies are needed to find causative factors and genes.

In summary, TFRCC is a rare subtype of low-grade malignant renal cell carcinoma with certain invasiveness, which usually occurs in young and middle-aged women. Its clinical and imaging manifestations have certain suggestive value, with unique morphological and immunohistochemical characteristics. The diagnosis depends on pathology and immunohistochemistry, and surgical resection is the preferred treatment. The overall prognosis is good, but there is a certain malignant potential,which needs long-term and close follow-up. If the disease progresses, the treatment plan for metastatic RCC should be considered. Due to the low incidence of TFRCC, there are few studies on this tumour;therefore, further studies are needed to enhance understanding and provide valuable information for diagnosis and treatment. No recurrence or metastasis was found in our case; however, further observation is needed in terms of survival time.

The existing case data suggest that the disease mainly occurs in women. Currently, the youngest reported case pertains to a 10-year-old child[9] in whom the right side was more affected than the left side. The clinical symptoms are not obvious and most lack specificity; they are found accidently during physical examination. In most symptomatic patients, symptoms manifest as gross haematuria and abdominal pain, while some patients show hypertension[10,11,12], repeated urinary stimulation symptoms[12,13], weight loss[13], and other symptoms(Table 1). For the preoperative diagnosis of common RCC, CT is the first choice. However, for TFRCC, preoperative ultrasound seems to be more accurate than CT in visualizing the mass. On plain CT, cystic-solid changes are usually seen with highdensity shadow, clear boundary, haemorrhage, and necrosis. Most of them show weak enhancement on enhanced scan, which is different to the obvious enhancement of other types. Moreover, eggshell-like calcification has been observed around the tumour, while the calcification in other types of RCC generally appears in the centre of the tumour. However, in our case, plain CT showed a moderate density shadow, while an enhanced scan showed continuous obvious uneven enhancement, inhomogeneous enhancement, and no obvious calcification, which was rarely seen in previous case reports.Magnetic resonance imaging generally shows a high signal on T1-weighted imaging and a low signal on T2-weighted imaging compared to the signal in the renal parenchyma. These characteristic imaging findings may have a certain suggestive value for preoperative consideration of TFRCC; however,pathological and immunological examination need to be performed for diagnosis.

Macroscopically, most of the tumours are clear with a false capsule and both cystic and solid, with occasional bleeding, necrosis, or cystic degeneration. The section has a medium texture and is greyish white to greyish yellow, which differs from the multi-coloured appearance of clear cell RCC. Microscopically, the most prominent feature of the tumour is the formation of the thyroid follicular carcinoma-like structure, and the follicular cavity is filled with a red dye colloid-like substance, which is similar to thyroid colloid-like substance. The cytoplasm of the tumour cells is bichromatic or eosinophilic and empty and bright, the nucleus is round and oval, and the heteromorphism is not obvious. Occasionally,the nuclear groove can be seen, the mitotic image is rare, and the Fuhrman grade is mainly grade 2.Most cases show positive expression of CK, CK7, vimentin, and EMA; negative expression of the thyroid markers TTF-1 and TG; and low Ki-67 proliferation index[14]. In our case, the tumour was solid,its boundary was unclear, the other histological characteristics were similar to those previously reported, and the Ki-67 proliferation index was 2%. The degree of malignancy of the tumour was low,and the postoperative recovery was good.

所有工業(yè)以太網(wǎng)組織都提供了模型，用來描述現(xiàn)有工廠如何與基于TSN的新設(shè)備協(xié)同工作?，F(xiàn)有工業(yè)網(wǎng)絡(luò)的接口由網(wǎng)關(guān)（Sercos）、帶耦合器（EtherCAT）或沒有任何特殊硬件（PROFINET RT）的接口組成。特別是PROFINET和EtherNet/IP計(jì)劃將其完整協(xié)議作為第2層用于TSN。這使得逐步過渡到TSN成為可能?？傊?，TSN將在新裝置中隨處可見，并逐漸以島或區(qū)段的形式導(dǎo)入至現(xiàn)有裝置中。

Laparoscopic partial nephrectomy was performed in December 2020. The patient recovered well after surgery and was discharged after 3 d. Fine-needle biopsy of the thyroid nodules was performed in 2021,and revealed no obvious pathological abnormalities .

The 60-year-old man presented with a ＞ 1-mo history of right lower back and abdominal pain.Computed tomography (CT) revealed small solid nodules under the capsule in the middle and lower part of the right kidney, leading to the suspicion of small RCC.

CONCLUSlON

目前，國(guó)能已有38個(gè)項(xiàng)目并網(wǎng)發(fā)電，累計(jì)裝機(jī)容量990MW，占全國(guó)總投產(chǎn)項(xiàng)目規(guī)模的18%左右，居全國(guó)第二位。在建項(xiàng)目5個(gè)，裝機(jī)容量150MW，儲(chǔ)備項(xiàng)目10個(gè)，裝機(jī)容量300MW。國(guó)能秸稈電廠主要布置在中部和北部地區(qū)，分布在山東省、吉林省、河北省、河南省、黑龍江省、安徽省等地[24-25]。

FOOTNOTES

Wu S and Xie K contributed equally to this work; Wu S, Li X, Liao B, Xie K and Chen W designed the research study; Wu S, Li X, Xie K and Liao B performed the research; Wu S and Xie K contributed new reagents and analytic tools; Li X, Xie K and Liao B analyzed the data and wrote the manuscript; all authors have read and approved the final manuscript.

Natural Science Foundation of Jiangxi Province, No. 2010GZY0806.

經(jīng)評(píng)分，模型組小鼠陰道病變情況普遍嚴(yán)重，病變小鼠數(shù)量較多，而給藥各組均得到有效改善，其中以黃柏堿（40 mg/kg）與加替沙星改善作用最為明顯。經(jīng)觀察，模型組小鼠陰道黏膜上皮壞死脫落、潰爛，出現(xiàn)炎性細(xì)胞浸潤(rùn)、黏膜充血及大量炎性物滲出等。給予不同劑量黃柏堿或加替沙星治療后，BV小鼠陰道病變得到不同程度的緩解，充血水腫、細(xì)胞浸潤(rùn)、組織潰爛、上皮壞死等均得到改善。經(jīng)HE染色發(fā)現(xiàn)，模型組小鼠陰道切片中有大量炎性細(xì)胞分布，而給藥組均得到不同程度緩解，HE染色結(jié)果見圖1，病理評(píng)分結(jié)果見表2。

Consent was obtained from the patient and his family for publication of this report.

The authors declare that there are no conflicts of interest.

The authors have read the CARE Checklist (2016), and the manuscript was prepared and revised according to the CARE Checklist (2016).

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China

Si-Cheng Wu 0000-0003-3429-1849; Xi-Ya Li 0000-0002-9017-1203; Bang-Jie Liao 0000-0002-8892-0180;Kun Xie 0000-0003-0628-2128; Wei-Min Chen 0000-0001-5634-4417.

Wang LL

Webster JR

Wang LL