the current standard of treatment for locally advanced rectal cancer ( uicc stages ii and iii ) includes a 5-fluorouracil ( 5-fu)-based preoperative radiochemotherapy ( rct ) , total mesorectal excision , and postoperative chemotherapy [ 1 , 2 ] . several randomized clinical trials during the last decades have demonstrated that neoadjuvant 5-fu - based rct significantly improves locoregional control of rectal cancer [ 3 , 4 ] . today , the limitation of the prognosis of individual patients is mainly determined by the occurrence of distant metastases in 3040% of patients . this led to the intensification of systemic therapy through integration of platinum derivatives , an approach that not only promises a therapeutic benefit but simultaneously bears the risk of increased toxicity . subsequently , to avoid unnecessary toxicity , more individualized and risk - adapted treatment approaches are needed and are currently being validated in several ongoing clinical trials . however , in rectal cancer , reliable biomarkers to predict the response to neoadjuvant rct , individual prognosis and occurrence of treatment - associated toxicity have not yet been established as part of the clinical routine . the adjuvant treatment strategy with 5-fu in combination with leucovorin and oxaliplatin is well established and has been used for nearly 10 years in the adjuvant treatment of uicc iii colon cancer . the neoadjuvant and adjuvant treatment with folfox against locally advanced rectal cancer ( uicc ii and iii ) is integrated in several randomized phase iii multicenter trials such as the cao / aro / aio-04 trial of the german rectal cancer study group . the cao / aro / aio-04 regimen consists of intravenous oxaliplatin ( 80 mg / m ) combined with leucovorin ( 400 mg / m ) and subsequent 5-fu infusion ( 2,400 mg / m ) , repeated every 14 days over 4 months ( 8 cycles ) . oxaliplatin is a platinum derivative whose therapeutic effect is based on alkylating effects . the platinum compound binds to dna forming cross - links , which inhibit dna replication and transcription , and so result in cell death [ 9 , 10 ] . for patients with chronic renal failure ( creatinine clearance < 30 ml / min ) , a dose reduction is necessary ( starting dose of 65 mg / m ) . common adverse reactions of oxaliplatin ( over 10% ) include central neurological , gastrointestinal , hematologic , and peripheral neuropathic reactions . typical side effects of oxaliplatin are a grade 34 neutropenia and in rare cases neutropenic fever . the peripheral neuropathy is very common ; it might affect the patient 's quality of life and might therefore lead to dose reductions . the acute form is characterized by peripheral , acral and facial paresthesia and pain , commonly being exacerbated by exposure to the cold . the chronic side effects of neuropathy grade 34 with decreased distal sensation and proprioception affect the extremities and are reversible in most patients . of note , we report on 2 cases of oxaliplatin - induced leukocytoclastic vasculitis with kidney involvement , a side effect which  to the best of our knowledge  was only reported in a single case before . written informed consent was obtained from the patients for the publication of this paper and any accompanying images . a 75-year - old man presented with a locally advanced adenocarcinoma of the rectum ( 37 cm above the anal verge , endoscopically staged as ut3 un ) . as he had received interstitial brachytherapy ( > 145 gy ) 2 years before as a treatment for prostate cancer ( ct2b , cnx , cm0 , gleason score 6 ) , the standard treatment of neoadjuvant rct with 50.4 gy and concomitant 5-fu ( + / oxaliplatin ) was not possible . an abdomino - perineal rectum exstirpation with implantation of a descendostoma was performed to remove the rectal cancer . the histopathological work - up revealed a pt3a , pn2b ( 21/31 ) , cm0 , l1 , v0 , g3 , r0 ( uicc iiib ) adenocarcinoma and thus adjuvant chemotherapy was strongly suggested according to the vote of the institutional interdisciplinary tumor board . eight weeks after surgery , the first cycle of adjuvant chemotherapy with 5-fu , leucovorin and oxaliplatin ( folfox-6 ) was scheduled . the cycle consisted of a bimonthly regimen with intravenous oxaliplatin ( 80 mg / m ) and leucovorin ( 400 mg / m ) administered on day 1 . 5-fu 2,400 mg / m followed on day 1 as a continuous infusion for 46 h. during the following 3 days , the patient developed fever that resolved spontaneously . fourteen days later , the patient showed disseminated petechiae with secondary hemorrhage , along with edema on both legs and interdigital ulceration . he reported that he had experienced arthralgia in his knees and elbows 4 days after the first dose of chemotherapy . his blood count showed microcytic , hypochromic anemia , leukocytosis of 13,900/l , elevated c - reactive protein of 90.1 mg / l , and an increase in the retention parameters ( urea 25 mg / dl ) , indicating an affliction of the kidneys . the chemotherapy was interrupted and the patient was admitted to the department of dermatology . on examination , there was palpable purpura with petechial hemorrhage on the lower limb in addition to massive edema on both lower legs ( fig . 1 ) . some petechiae were also found on the lower arms and the abdomen . the patient did not complain about abdominal pain and 3 tests for occult blood in the stool were negative . after 2 days , the renal parameters were rising ( creatinine 1.33 mg / dl ; normal range 0.51.0 mg / dl ) and the patient developed proteinuria of 1,200 mg / day in the 24-hour urine collection . because of the putative renal involvement , therapy with a high - dose corticosteroid ( prednisolone 80 mg / day ) , a proton pump inhibitor ( pantoprazole 40 mg / day ) and osteoporosis prophylaxis ( calcium carbonate and cholecalciferol 500 mg and 10 g b.i.d . in addition , the patient was prescribed an ace - inhibitor ( ramipril 2.5 mg / day ) for renal protection . an infectious origin of the leukocytoclastic vasculitis was considered implausible because there were no respective clinical symptoms and serological tests were negative for hepatitis a , b and c as well as for an infection with streptococci . g / l ) , c4 ( 0.25 g / l ) , p - anca - if ( < 1:20 ) , and ana - if ( > 1:80 ) , were not elevated and no circulating immune complexes were detected . a punch biopsy from the active area of the frontal aspect of the right lower leg showed typical features of leukocytoclastic vasculitis ( fig . nuclear dust in the higher corium , extravasated erythrocytes , focal small - vessel edema , endothelial cell swelling within the vessels and fibrinoid deposition . direct immunofluorescence revealed igm , iga , c3 , and fibrinogen deposition in the small vessels of the dermis . in our opinion , there was strong evidence for drug - induced toxicity as the cause of the vasculitis , so chemotherapy with oxaliplatin was discontinued . the patient was treated with prednisolone at a decreasing dosage for the next 6 weeks . under the steroid therapy after 2 weeks , there was evidence of hematuria ( > 20 erythrocytes ) and proteinuria ( 745 the urine analysis showed an increase in renal parameters with creatinine 2.41mg / dl , urea 43 mg / dl , egfr 26.3 , a proteinuria of 1,800 mg / day in a 24-hour urine collection , and a creatinine clearance of 40.1 ml / min . the patient was admitted to the department of nephrology with the clinical diagnosis of acute renal failure , presumably as a consequence of acute glomerulonephritis . the percutaneous renal biopsy showed a focal segmental extravascular necrotizing proliferating glomerulonephritis . because gbm - antibodies ( 0.4 u / ml ) or cryoglobulins ( < 0.2% ) were not detectable , the most likely cause of renal failure was a renal manifestation of the leukocytoclastic vasculitis . under high - dose steroid therapy ( prednisolone 250 mg for 3 days followed by tapered doses ) , the renal function improved slowly . unfortunately , during further follow - up , the patient had developed tumor progression with pulmonary metastases at the 12-month follow - up visit . consequently , a palliative regimen with folfiri ( 5-fu , leucovorin and irinotecan ) was scheduled . under this treatment recent mri and ct scans revealed a progressive disease with new metastasis - like lesions in the thoracic spine and suspect lymph nodes in the retroperitoneal , iliacal and inguinal region . we also treated a 71-year - old male patient with similar symptoms after chemotherapy with folfox-6 and bevacizumab for colon cancer with hepatic metastases [ pt3 , pn0 ( 0/33 ) , pm1 ( hepatic ) , g2 , r0 ] . initially , he had received surgical treatment with a right hemicolectomy and an atypical liver resection of some of the lesions . after the subsequent postoperative chemotherapy with folfox-6 and bevacizumab for 4 cycles , restaging was performed . due to the remaining hepatic metastases , a right hemihepatectomy was performed . except for increased s - ana - if activity ( 1:320 ) , the rheumatoid factors were negative . a punch biopsy from an active hemorrhagic lesion again confirmed the diagnosis of a leukocytoclastic vasculitis . shortly after diagnosis , the patient showed clinical symptoms of acute renal failure and his renal parameters increased to a serum creatinine of 2.5 mg / dl and an urea of 69 mg / dl , necessitating forced diuresis in addition to systemic corticosteroids for the next 2 months . the nephrotic syndrome with microhematuria persisted for 2 months of continued cortisone therapy . a renal biopsy was repeated 2 months later and showed an iga nephritis with focal segmental and global glomerulosclerosis . as treatment for the chronic renal failure grade iii , assuming that drug toxicity was the cause of the vasculitis , the supporting chemotherapy was prematurely terminated . within the following 12 months , the patient regretfully developed new metastases in the right lung segment and also showed bifocal liver metastases in the remaining left liver lobe . the dose reduction was 75% and he received additional fluids for renal protection . under this treatment , the patient again suffered from acute or chronic renal failure , which made hemodialysis necessary . oxaliplatin is a third - generation platinum alkylating agent currently used to treat a great number of malignancies , including both locally advanced and metastatic colorectal cancer . unfortunately , the use of oxaliplatin is associated with a plethora of adverse effects . while some of these effects , like nausea or thrombocytopenia , are common reactions to many cytostatic drugs , oxaliplatin has been reported to induce some rather unique side effects . with the report of these 2 cases , we have documented a very rare oxaliplatin - induced side effect with a potentially dramatic impact on the affected patients . physicians should be aware of this rare , yet potentially detrimental adverse effect of oxaliplatin when employing it as a standard chemotherapeutic substance or as a part of novel combination therapies . to our knowledge , there has been only 1 case report prior to our observations reporting leukocytoclastic vasculitis as an adverse effect of treatment with oxaliplatin .