pleomorphic carcinoma ( pc ) is a rare malignant lung tumor characterized by dual - cell components including spindle or giant cells as well as epithelial cells . pc has been reported to have a more aggressive clinical course and a poorer survival compared to other histological types of non - small cell lung cancer ( nsclc ) [ 1 , 2 ] . we report the case of a patient with pc and a single brain metastasis that achieved long - term recurrence - free survival following treatment with combined modality therapy . a 71-year - old male presented with aphasia and muscle weakness of the left side of his body . he was suspected of having a central nervous system disorder and underwent head brain ct that showed a 50  50 mm mass lesion in the right frontal lobe ( fig . his chest x - ray showed a mass shadow with a cavity in the right - middle lung field ( fig . the chest ct also showed a 70  68 mm mass with a cavity in the right lower lobe ( fig . the level of tumor markers like carcinoembryonic antigen , cytokeratin 19 fragments and pro - gastrin - releasing peptide were not elevated . based on these clinical findings , the patient was diagnosed with lung cancer with a single brain metastasis . craniotomy was performed because the patient 's central nervous system 's symptoms were severe and his eastern cooperative oncology group performance status was zero . the brain tumor in the right frontal lobe was completely removed , and the pathological diagnosis was confirmed as sarcomatoid pattern carcinoma . a ct - guided percutaneous lung biopsy proved that the pathological diagnosis of the right lung mass was spindle cell carcinoma . the patient was therefore diagnosed as having pleomorphic carcinoma of the lung with a single brain metastasis ( clinical t3n0m1b stage iv ) . after craniotomy , the patient underwent 6 courses of chemotherapy ( carboplatin auc 4 on day 1 and gemcitabine 800 mg / m on days 1 and 8 , repeated every 3 weeks ) . after chemotherapy , the chest ct showed a reduced nodular shadow ( 62  50 mm ) ( fig . 1d ) , while f - fluorodeoxyglucose positron emission tomography showed no uptake in the lymph nodes ( data not shown ) . the patient achieved a partial response by preoperative chemotherapy and underwent a right - lower lobectomy , partial resection of a right s2 segment , parietal pleurectomy , and mediastinal lymph node dissection through a posterolateral thoracotomy . this surgery was required because of the possibility of invasion into the right upper lobe and the parietal pleura . microscopically large , spindle - shaped atypical cells had sarcomatously proliferated into most of the tumor portions ( fig . immunohistochemically , the mib-1 index of the specimen obtained by ct - guided percutaneous lung biopsy before preoperative chemotherapy was high at 60% ( fig . 2c ) , whereas that of the resected tumor was low at 10% ( fig . pc is rare , accounting for 0.31.0% of all lung cancers ; it is defined as a poorly differentiated nsclc . in a recent large study on patients with stage i  iii lung cancer , the overall 5-year survival rate and mean survival time of these patients were reported to be significantly lower and shorter than that of patients with other types of nsclc ( 36.7 vs. 59.4% , and 22.8 vs. 96 months , respectively ) . therefore , patients with pc have a significantly poorer outcome than patients with other types of nsclc . in the present case , the patient underwent preoperative chemotherapy after craniotomy . the national comprehensive cancer network recommends neoadjuvant chemotherapy combined with surgical treatment or surgical treatment combined with adjuvant chemotherapy in nsclc cases with brain metastasis ( tnm category t12 , n01 , t3n0 if the metastasis can be controlled ) . although previous papers showed that pc had a poor response to chemotherapy regimens , there is a report indicating the efficacy of chemotherapy for pc . in our case , gemcitabine - based chemotherapy was effective and suggested that this treatment was potentially useful for pc . the following discussion includes the possible reasons why the present case achieved long - term survival . .   showed the following 4 factors that contributed to the poor prognosis for a pc survival : ( 1 ) tumor size > 5 cm , ( 2 ) stage greater than i at presentation , ( 3 ) presence of distant metastases , and ( 4 ) lymph node metastases . in this case , the absence of lymph node metastasis was a good prognostic factor . these 4 factors only include the tnm classifications and are common prognostic factors for pc and other nsclcs . however , patients with pc have poorer outcomes than those with other nsclcs , and it is therefore necessary to investigate specific prognostic factors for pc . in the present case , the mib-1 index of the immunohistochemical specimen obtained by ct - guided percutaneous lung biopsy before preoperative chemotherapy was high at 60% ( fig . 2c ) , although it was reduced to 10% in the resected tumor ( fig . mib-1 is present during all active phases of the cell cycle ( g1 , s , g2 , and mitosis ) , but absent in resting cells ( g0 ) . this property makes it an excellent marker for determining the so - called growth fraction of a given cell population . in patients with pc , a low mib-1 index ( < 35% ) moreover , there is a report in which the mib-1 index was significantly lower after gemcitabine - based chemotherapy and exerted a true antiproliferative effect on tumors in vivo . reduced proliferation with gemcitabine - based chemotherapy may partly be because of increased apoptosis in actively proliferating cells so that the residual population would be enriched by mib-1-negative cells . in our case , the mib-1 index was reduced by gemcitabine - based chemotherapy , which may have led to long - term disease - free survival . the mib-1 index may therefore be a useful biomarker of the response to chemotherapy , with the reduction in the index following preoperative chemotherapy representing a response marker that reflects the proliferation of tumor cells . the changes in the mib-1 index caused by preoperative chemotherapy may therefore provide useful information for deciding the regimen for adjuvant chemotherapy .
pleomorphic carcinoma ( pc ) is a rare malignant lung tumor with a poorer prognosis compared to other histological types of non - small cell lung cancer . 
 however , several recent immunohistochemical studies revealed that a low mib-1 index is a good prognostic marker in patients with pc . 
 we report the case of a patient with pc and a single brain metastasis that achieved long - term recurrence - free survival following treatment with combined modality therapy . in this case 
 , the mib-1 index was reduced by gemcitabine - based chemotherapy , which may have led to long - term disease - free survival . 
 the mib-1 index may be a useful biomarker for the response to chemotherapy .