primary malignant lymphoma originating from the chest wall is often associated with preceding pleural disease , such as pleural tuberculosis or chronic pyothorax . it is classified as diffuse large b - cell lymphoma associated with chronic inflammation according to the 2008 world health organization ( who ) classification ( 1 ) . we experienced a malignant lymphoma originating from the chest wall that differed in many respects from pyothorax - associated lymphoma ( pal ) , such as the presence of rib destruction , a good prognosis , and no preceding pleural disease . it is important to consider the possibility of malignant lymphoma when we see pleural masses , even if there is no preceding inflammatory disease . an 84-year - old woman presented to a local clinic with dyspnea on exertion and left back pain persisting for a month . she was admitted to our hospital because of left pleural effusion on a chest x - ray . she suffered hypertension and dyslipidemia but had no history of pleural tuberculosis or chronic pyothorax , nor a smoking history or dust exposure . on examination , her vital signs and oxygen saturation were normal ( spo2 : 96% ambient air ) . a chest examination revealed a mass on the left side of her back with pain and decreased breathing sounds in the left lower - lung field . laboratory tests revealed elevated levels of c reactive protein , lactate dehydrogenase ( ldh ) , and soluble interleukin-2 receptor ( sil-2r ) ( table 1 ) . , an intercostal drainage tube was inserted , and after drainage , chest computed tomography ( ct ) ( fig . 2 ) revealed an irregular pleural mass invading her left chest wall with rib destruction and pleural effusion . the mass was adjacent to the posterior mediastinum , but the lateral side of the mass was thick and invading the chest wall , so we diagnosed this mass as a chest wall tumor . a chest ct scan exhibiting a mass invading the left chest wall with pleural effusion . the pleural fluid was serous and not purulent . a fluid analysis showed it to be exudative , and 81% of the white blood cells were lymphocytes . the fluid culture was negative , and cytology did not show any evidence of malignancy ( table 1 ) . the histopathology results supported a diagnosis of diffuse large b - cell lymphoma ( dlbcl ) that was positive for cd10 and cd20 but negative for cd3 and cd5 ( fig . the histopathological findings of the tumor showing diffuse large cell , non - hodgkins lymphoma , immunohistochemically stained positive for cd10 and cd20 . 18-fluorodeoxyglucose positron emission tomography / computed tomography ( fdg - pet / ct ) revealed high fdg uptake in the left chest wall mass without any other uptake ( fig . 4a and b ) , so we diagnosed her with primary malignant lymphoma originating from the chest wall . we reconfirmed her medical history , and she never had either tuberculous pleurisy or pyothorax . fdg - positron emission tomography ( pet)/ct revealing significant accumulation of fdg in the left chest wall mass ( a , b ) her performance status ( ps ) was 3 because of her back pain and fatigue . owing to her bad ps and age , it was difficult to perform an operation or administer combination chemotherapy with rituximab , so low - dose oral etoposide ( 50 mg / day d1 - 14 , her pleural effusion disappeared within two weeks , her back pain disappeared , and her ps improved to 1 within a month . she continued oral chemotherapy and maintained a good ps for one year after the diagnosis . primary malignant lymphoma originating from the chest wall accounts for about 0.3 - 1.0% of extranodal lymphoma . this lymphoma is mostly associated with underlying diseases , like tuberculous pleurisy or pyothorax after artificial pneumothorax , and is considered to be caused by chronic inflammation of the pleura . it is classified as diffuse large b - cell lymphoma associated with chronic inflammation according to the 2008 who classification ( 1 ) . we therefore consider this a non - pyothorax associated lymphoma ( npal ) , originating from the chest wall without preceding pleural disease . the possibility of malignant lymphoma must be considered when pleural masses are observed , even if there is no preceding inflammatory disease . while pal tends to develop more than 20 years after chronic pyothorax and has male predominance , npal can occur in the relatively young ( under age 50 , about 24% ) and without marked gender differences . indeed , of the 21 reported npal cases in japan , the average age is 64 ( 17 - 84 ) years , and the ratio of males to females is 4:3 ( table 2 ) . in pal , the average age is 70 ( 51 - 86 ) years , and the ratio of males to females is 8.8:1 ( 2 ) . report of primary malignant lymphoma originating from the chest wall without a history of chronic pyothorax in japan . rt : radiotherapy , ct : chemotherapy , op : operation mzl : marginal zone lymphoma , dlcl : diffuse large cell lymphoma , ptcl : peripheral t cell lymphoma , dmcl : diffuse mixed cell lymphoma dmecl : diffuse medium - sized cell lymphoma , dscl : diffuse small cell lymphoma , fl : follicular lymphoma b : b - cell type , a : anaplastic type the imaging features of primary malignant lymphomas originating from the chest wall are the tumor spreading along the pleura , sometimes involving the ribs but mostly maintaining rib structure ( 3 ) . in our case , invasion and destruction of the rib was observed , so we first considered lung cancer or mesothelioma . of the 21 reported npal cases , bone destruction was seen in 6 ; pleural effusion was also seen in 6 of these 21 cases , but only 2 cases had lymphoma cells in the pleural fluid . a previous study detected epstein - barr ( eb ) viral dna ( ebv - dna ) in lymphoma cells , indicating that eb viral infection contributes to the pathogenesis of pal ( 4 ) . however , the findings on an evaluation of the presence of ebv - dna in 7 of the 21 reported npal cases were all negative , so npal pathogenesis might differ from that of pal . in our case , ebv - dna was seen in the pleural effusion , but we could not check the ebv - dna status in the biopsy specimen because of insufficient sample volume . the 2008 who classification of tumors of hematopoietic and lymphoid tissues has recognized a new provisional entity : ebv - positive dlbcl of the elderly ( 1 ) . this tumor is defined as an ebv - positive monoclonal large b - cell lymphoproliferative disorder arising in immunocompetent patients over 50 years of age . patients with this disease often have constitutional symptoms , such as fever , malaise , and weight loss , and extranodal involvement like the skin , lungs , pleural effusion , stomach , and tonsils . in addition , the histological features like extensive necrosis , lymphoid infiltration , and r - s cell like giant cells characterized in ebv - positive diffuse large b - cell lymphoma ( dlbcl ) of the elderly were also not seen in this case . while we can not exclude the possibility of this disease because we could not assess the ebv - dna status of the tumor , we suspect that the present case is a dlbcl not otherwise specified in the who classification . the prognosis of pal is generally poor , with a 2-year survival rate of 31.4% and median survival time ( mst ) of about 9 months ( 7 ) . npal prognosis is slightly better : 5 of the 21 historical patients died , 1 recurred after remission , and the remaining 15 experienced remission following operation , chemotherapy , or radiation therapy ( rt ) . we suppose these differences occurred because pal patients tend to have low ps and low respiratory function due to preceding disease or are difficult to operate on due to chronic inflammation . another possibility is that the grade of malignancy or biochemical features are different between these two pleural lymphomas ( 8) . no standard treatment regimen for primary pleural lymphoma has been established , and combination or monotherapy of operation , chemotherapy , and rt was performed for each case . of the 21 historical npal cases , 8 received operation for the first treatment , but 5 of those 8 patients were not diagnosed before surgery . in the 15 patients who were diagnosed before treatment , the first treatment was chemotherapy in 8 patients , surgery in 3 , a combination of chemotherapy and rt in 2 , and rt only in 2 . in two cases , nakajima et al . reported that surgery was a prognostic factor of pal ( 9 ) , and nagata et al . recommended operation on npal because recurrence often happened with chemotherapy or rt ( 10 ) however , in the 21 reported npal cases , there were no significant differences in the remission rate and survival rate between the operated and the non - operated group . no fatal cases were reported among the patients with diagnostic operation , but there is some bias , because these cases were able to undergo complete resection due to their small size or low degree of invasion . surgery may therefore not be a first choice in elderly patients or patients with substantial invasion . the guidelines of hematopoietic malignancy in japan do not recommend any specific treatment for elderly or poor - ps patients . in particular , there is little evidence available regarding the optimum treatment for the patients over 80 years of age . we therefore administered low - dose oral etoposide , which is considered a salvage therapy for malignant lymphoma , taking into account the patient 's age and poor ps . its safety for elderly patients ( 11 ) and a case with long - term survival ( 12 ) have been reported . the present patient exhibited a complete response and maintained good ps for longer than one year , experiencing only partial remission . our case represents a compelling treatment option , particularly in elderly or poor - ps patients who might not tolerate surgical resection or extensive chemotherapies . low - dose oral etoposide was able to produce a remarkable response in just such a patient . to improve the patient 's quality of life and chance of survival , it is important to consider the possibility of npal , even with a chest wall tumor with rib destruction and no history of preceding pleural disease .
an 84-year - old woman presented to our hospital with dyspnea on exertion and left back pain . 
 chest x - ray and chest computed tomography ( ct ) revealed an irregular pleural mass invading her left chest wall with rib destruction and pleural effusion . 
 ct - guided needle biopsy revealed diffuse large b - cell lymphoma . 
 low - dose oral etoposide produced a complete response , and she continued oral chemotherapy for one year after the diagnosis and maintained good performance status . 
 we herein report a very rare case of non - pyothorax - associated lymphoma that nonetheless resulted in great recovery .