MA Ying,YU Rong,YANG Hao*（.Affiliated Hospital of Inner Mongolia Medical University，Hohhot Inner Mongolia 0000；.Department of Radiation Oncology (Inner Mongolia Cancer Hospital &Affiliated People’s Hospital of Inner Mongolia Medical University) Hohhot Inner Mongolia 0000）

ABSTRACT:Objective To investigate the clinicopathological features,diagnosis,differential diagnosis and prognosis of clear cell tumor of lung.Methods To review a case of clear cell tumor of lung which was admitted to our hospital at the end of 2018,and review the relevant literatures.Results The patient was admitted to the hospital for the main reason that the mass in the middle lobe of the right lung was found in the physical examination for 10 days,and the postoperative pathological report was clear cell tumor of lung.Pathological diagnosis:clear cell tumor of lung.Conclusion The clinical treatment of clear cell tumor of lung is mainly complete surgical resection of the mass,the prognosis of most cases is good,but some cases may relapse,we should pay attention to a long follow-up.

KEY WORDS:lung；clear cell tumor；diagnosis；prognosis

1 Clinical data

The patient,female,66 years old,was admitted to the hospital on December 17,2018 mainly due to “10 days of mass in the middle lobe of the right lung found during physical examination”.During the physical examination 10 days ago,the mass of the middle lobe of the right lung was found.CT scan of the outside hospital showed:sclerosing hemangioma of the middle lobe of the right lung? No obvious positive signs were found on admission.Auxiliary examination:blood routine,liver and kidney function examples,electrocardiogram and electromyography were generally normal.Enhanced chest CT:sclerosing hemangioma in the middle lobe of the right lung? Intraoperative management:the right lateral pectoral incision was inserted into the chest from the upper margin of the sixth costal margin.The tumor was located at the level of the middle lobe of the right lung,with irregular shape,about 7.5×5.5×2.5cm in size,tough texture,intact capsule,and adhesion to the middle lobe.The tumor and part of the middle lobe of the right lung were removed with the cutting and suturing device.The tumor was bagged and removed.Postoperative pathological findings were as follows.Gross findings:the mass volume was about 7×5.5×2.5cm,with partial lung tissue of 6×2.5×1cm.The surface of the tumor was smooth,the capsule was complete,multiple sections were cut,the cut surface was solid,dark red was soft,and more materials were obtained.Pathological diagnosis:PECOMA (clear cell tumor,sugar tumor).Immunohistochemical Results Vim (+),ttf-1 (-),Ki67 (3%+),CD34 (vascular +),CK7 (-),Syn (-),S100 (-),HMB45 (partially+),ckae1/3 (-),CD43 (-),CD68 (-),MelanA (focal +),SMA (-).

Figure 1 HE staining ×400

Figure 2 This proves:＊＊＊＊＊

2 Discussion

With clinical features of clear cell tumor of the lung,clear cell tumor of the lung (CCTL) is a rare mesenchymal tumor with peripheral epithelioid cell differentiation.It is also known as “sugar tumor” because of its rich glycogen content in the envelope.It was first reported by Liebow and Castleman in 1963.So far,only over 50 cases have been reported in the world,and only over 20 cases have been reported in China.The age of onset is 8～73 years old,and 75% of the patients are 45～59 years old.There is no significant difference between men and women.Clear cell tumors of the lung were classified as Pecoma by WHO in 2013,which is mostly located in the periphery of the lung and some in the trachea.Most of these tumors are isolated round or ovoid nodules with clear boundaries,and a few cases may present multiple foci.There are biological behavior for the boundary,most of the benign tumors,rare low -grade malignant.Diagnosis key points:most patients have no clinical symptoms,and it is difficult to make a clear diagnosis before surgery.Most patients are diagnosed by postoperative pathology and immunohistochemistry.Immunohistochemistry was mainly HMB-45,Melan-A positive,partial cases of SMA,and a few cases of NSE,Syn(focal or weakly positive),CK,TTF1,EMA,s-100,CD117,desmin,CgA which were all negative.In recent years,CD34 is considered to be helpful for the diagnosis of clear cell tumor of lung.Immunohistochemistry was mainly HMB-45,Melan-A positive,partial cases of SMA,A few cases of NSE,Syn (focal or weakly positive),CK,TTF1,EMA,s-100,CD117,desmin,CgA which were all negative.In recent years,CD34 is considered to be helpful for the diagnosis of clear cell tumor of lung.Immunohistochemistry was mainly HMB-45,Melan-A positive,partial cases of SMA,and a few cases of NSE,Syn(focal or weakly positive),CK,TTF1,EMA,s-100,CD117,desmin,CgA which were all negative.In recent years,positive CD34 is considered to be helpful for the diagnosis of clear cell tumor of lung.Differential diagnosis:It is compared with primary clear cell carcinoma of the lung,metastatic clear cell carcinoma of the lung and clear cell carcinoid of the lung.Treatment and prognosis of pulmonary hyaline cell tumor:cases of pulmonary hyaline cell tumor are rarely reported,preoperative diagnosis is difficult,and there is no classified report.This type of tumor is usually benign,but a small number of cases with malignant biological behaviors have been reported.One patient was clearly diagnosed as pulmonary clear cell tumor,and one fatal case was reported to have developed abdominal metastasis and liver metastasis after 10 years of postoperative follow-up.The principle of WHO treatment suggests complete surgical resection without other adjuvant therapy.Therefore,lung clear cell tumor should not be observed for a long time,but should be removed as soon as possible and followed up for a long time.