improvements in technology have led to increased sensitivity of ct imaging , resulting in the detection of smaller pulmonary nodules . for patients with both an extrathoracic malignancy and indeterminate pulmonary nodules , however , in a study by o et al .   of patients with a known extrathoracic malignancy and indeterminate pulmonary nodules with no fdg uptake , or fdg uptake less than that of the mediastinum , it was found that more than 19% of the indeterminate pulmonary nodules were malignant . once solitary or multiple pulmonary nodules have been discovered by radiologic testing in patients with a known primary malignancy , there may be radiologic features that suggest a diagnosis , but these features can not reliably distinguish between benign and malignant etiologies . features of pulmonary nodules seen in patients with a known primary extrathoracic malignancy associated with malignant rather than benign disease are : ( 1 ) the lesion is non - calcified ; ( 2 ) the lesion is ovoid rather than linear in appearance ; ( 3 ) the lesion is in close proximity to an adjacent blood vessel ; ( 4 ) the lesion has reticular changes ; ( 5 ) the lesion is located at the lung bases and subpleural space , and ( 6 ) an increased size of the lesion . the primary pulmonary venous drainage pattern is characteristic of renal cell , breast , head and neck , and testicular carcinoma . statistically , the most common primary malignancies that result in pulmonary metastasis are from breast , colorectal , and renal cell carcinoma , uterine leiomyosarcoma , and head and neck squamous cell carcinoma . both cannon ball and miliary types of pulmonary nodules are associated with renal cell cancer and malignant melanoma . this is most frequently seen in colorectal carcinoma . it may also be seen in osteosarcoma , carcinoma of the kidney , testicle or breast , and malignant melanoma . metastases that tend to hemorrhage ( e.g. choriocarcinoma , angiosarcoma , renal cell carcinoma , melanoma , thyroid carcinoma , and kaposi 's sarcoma ) may have indistinct borders . cavitation occurs in less than 5% of malignant lesions , and is most commonly seen in squamous cell carcinoma from a head and neck , or lung origin , sarcoma , and after treatment . the american college of chest physicians recommends that , in patients who are candidates for curative treatment , each nodule be evaluated individually , as necessary , and that curative treatment not be denied unless there is histopathologic confirmation of metastasis . we present the case of a patient , diagnosed with a primary bladder carcinoma , who was found to have hodgkin 's lymphoma presenting as multiple pulmonary nodules . after treatment with abvd , there were favorable anatomic and metabolic responses to therapy , as evidenced by resolution of previously hypermetabolic cervical lymphadenopathy , and significant improvement in axillary , intrathoracic and intra - abdominal disease . our patient is a 57-year - old man with a past medical history significant for chronic left anterior and posterior cervical lymphadenopathy , which had begun 20 years earlier . biopsy of these lymph nodes had been performed many years ago and , by patient report , had demonstrated benign disease . the patient was in his usual state of health until june 2011 when he experienced a sudden onset of gross hematuria . he went to the emergency room , and a ct scan of the abdomen and pelvis was performed . the ct scan demonstrated multiple pulmonary nodules located in the left lung base , in addition to several bilateral sub - centimeter pulmonary nodules . there was non - specific lymphadenopathy in the retroperitoneum as well as a 1.9-cm mass - like density seen adjacent to the left posterior bladder , suggesting malignancy . a ct scan of the chest was performed and demonstrated multiple pulmonary nodules bilaterally , suggesting metastatic disease . other nodules measured 1.6 , 2.0 , and 0.8 cm . the patient then underwent a cystoscopy with transurethral resection of the bladder tumor . microscopic examination demonstrated the presence of multiple malignant spindle - shaped cells with inflammatory changes . these slides were also reviewed at an outside university pathology department , and the pathologic diagnosis was confirmed . on june 9 , 2011 , the patient underwent a ct - guided biopsy of a left lower lobe pulmonary nodule . the patient presented to our clinic for a second opinion regarding treatment as he had been advised to undergo treatment for metastatic bladder carcinoma . on examination , left cervical lymphadenopathy was palpated . on june 27 , 2011 , a pet / ct scan demonstrated multiple hypermetabolic lymph nodes in the neck . there were multiple hypermetabolic lesions noted in the paratracheal , prevascular and hilar lymph nodes bilaterally . a right lower lobe mass , 3.8 cm , was hypermetabolic with an suv of 14.2 . there were small nodules in the left cardiophrenic angle and left diaphragmatic pleura that were without associated metabolic activity . on june 29 , 2011 , a core biopsy of a left - sided axillary lymph node was non - diagnostic . an excisional biopsy of a left axillary node was performed on july 7 , 2011 , and demonstrated classical hodgkin 's lymphoma . bone marrow aspiration and a biopsy performed on july 15 , 2011 , demonstrated involvement of marrow with hodgkin 's lymphoma . cystoscopy and repeat biopsies of the bladder , performed on the same day as the bone marrow aspiration , revealed no abnormalities . on july 25 , 2011 , the patient started chemotherapy ( abvd ) . after 4 cycles of abvd , a pet / ct scan on october 3 , 2011 , demonstrated favorable anatomic and metabolic responses to the therapy , as evidenced by resolution of previously hypermetabolic cervical lymphadenopathy , and significant improvement in axillary , intrathoracic and intra - abdominal disease . radiologic features of pulmonary nodules may suggest a diagnosis , but these features are frequently unreliable . in patients with a known extrathoracic malignancy and multiple small pulmonary nodules , the reported rate of malignancy in these nodules , based on several studies , has been widely variable . a total of 146 patients with a single known primary malignancy and multiple pulmonary nodules were biopsied . of these biopsy specimens , the authors concluded that , in patients who have a known primary malignancy and multiple pulmonary nodules , biopsy of these nodules will rarely change the clinical course . they also concluded that the overwhelming majority of patients studied could have been treated based on the pre - biopsy presumptive diagnosis . other studies have indicated that the likelihood of pulmonary nodules representing malignancy in patients with a known extrathoracic malignancy is not as high as compared to what was reported in the study by patz et al . . in a study by ginsberg et al . , vats was performed in patients with pulmonary nodules measuring less than 1 cm . when a single pulmonary nodule was resected via vats in patients who had a known malignancy , 59% of those nodules were found to be malignant . when multiple pulmonary nodules were resected via vats in patients who had a known malignancy , 64% of patients had at least one nodule which was found to be malignant . the size of the pulmonary nodules in patients with a known malignancy may be predictive in determining the likelihood of malignancy . in the study by ginsberg et al . , in patients with a known primary malignancy , 84% of pulmonary nodules with a diameter more than 1 cm were malignant , as opposed to 49% of pulmonary nodules with a diameter less than 1 cm . although increased size of pulmonary nodules may be predictive of malignancy , 42% of pulmonary nodules smaller than 0.5 cm were still found to be malignant . a study by khokhar et al .   evaluated the medical records of 151 patients who had a history of non - thoracic malignancy and the presence of non - calcified pulmonary nodules . out of those 151 patients , 64 ( 42% ) were diagnosed with malignant nodules , 32 had newly diagnosed lung cancers , 28 had metastatic spread of their primary cancers , and 4 had either cancers that were new or of undetermined etiology . on multivariable analysis , nodule size and previous tobacco exposure were predictive of malignancy . evaluated the charts of patients with a known extrathoracic malignancy and who were found to have a solitary pulmonary nodule by chest imaging . patients with carcinoma of the head and neck , breast , cervix , bile ducts , esophagus , prostate or stomach were more likely to have primary bronchogenic carcinoma rather than lung metastasis . patients with carcinoma of the salivary glands , adrenal glands , colon , parotid gland , kidney , thyroid , thymus , and uterus had fairly even odds . patients with melanoma , sarcoma , or testicular carcinoma this study suggests that the primary malignancy type may be predictive of the pulmonary nodule 's etiology . these findings suggest the need for clinical correlation , and a low threshold for diagnostic biopsy in patients with extrapulmonary cancers and non - calcified pulmonary nodules . in this particular case , the specific pattern or features of the pulmonary nodules viewed in historical and clinical contexts may have been helpful in determining diagnosis . pulmonary nodules from non - hodgkin 's lymphoma are preferentially found in the lower lobes , and are occasionally surrounded by a halo of ground - glass attenuation , or contain air bronchograms . enlarged mediastinal or hilar lymph nodes may not be present . non - hodgkin 's lymphoma may also be seen as plaque - like or nodular densities in the pleura . hodgkin 's lymphoma involving the lung may present in a variety of radiographic patterns , including well - defined or ill - defined pulmonary nodules . among patients with hodgkin 's lymphoma , 6774% have abnormal radiographic findings at presentation . in those patients with abnormal radiographic findings , prevascular and paratracheal lymph nodes are most commonly affected in hodgkin 's lymphoma . as demonstrated in this case study , radiographic information obtained by ct scan for our patient , the results of the diagnostic biopsy had critical prognostic and therapeutic implications . prognostically , a patient who has carcinosarcoma of the bladder metastatic to the lung has a far different life expectancy as compared to a patient with two separate and potentially curable malignancies . in addition , chemotherapy used in the setting of metastatic carcinosarcoma of the bladder would have been substantially different from the treatment used in this patient to ultimately attain clinical remission . as the sensitivity of radiologic studies continues to improve , clinicians are more often likely to be confronted with the diagnostic dilemma of pulmonary nodularity discovered in patients with a known primary extrathoracic malignancy . this case illustrates that although radiologic features of pulmonary nodularity may help predict probability of malignancy , ultimately these characteristics are unreliable , and that it is critically important to perform a diagnostic biopsy of these nodules in patients with a known primary extrathoracic malignancy .
the screening of patients with a known primary extrathoracic malignancy for pulmonary metastasis may result in the identification of solitary or multiple pulmonary nodules . 
 radiologic features of these pulmonary nodules may suggest a diagnosis , but these features can not reliably distinguish between benign and malignant etiologies . 
 we present the case of a patient , diagnosed with carcinosarcoma of the bladder , who was found to have multiple pulmonary nodules by ct evaluation . 
 physical examination of the patient demonstrated the presence of cervical and axillary lymphadenopathy . 
 an excisional biopsy of an axillary lymph node confirmed the diagnosis of hodgkin 's lymphoma . 
 this case report demonstrates that radiographic information obtained by ct scan must be carefully correlated with the history and physical examination of the patient . 
 this case report also demonstrates the importance of diagnostic biopsy of pulmonary nodularity discovered in patients with a known primary extrathoracic malignancy . 
 the assumption that these pulmonary nodules represented metastatic malignancies would have had crucial prognostic and therapeutic implications .