a 37-year - old african american male with widely metastatic adenocarcinoma and bilateral inguinal lymphadenopathy was diagnosed with colon cancer . colon carcinomas are unlikely to present with inguinal lymphadenopathy , making this case unique in itself . a 37-year - old man presented with right groin pain which was thought to be a hernia due to excess working out . months after the initial presentation , the pain returned and he again sought medical attention . he reported severe groin pain that originated in the right groin and radiated posterior to the right buttock , thigh , and leg . in addition to the pain , he also endorsed a 40-pound weight loss over the past six months and also claimed to have a decreased appetite . he did have some constipation for the past one week , but denied any abnormality of his stool consistency , denied bright red blood or melanic stools . of note , at six months of age , he was found to have a bladder cancer ; specifics were unknown by him or his family . as per his family , it was initially resected without the need for any adjuvant chemotherapy or radiation . throughout his childhood , he had recurrent urinary tract infections which eventually by the age of nine years required an ileal conduit to be surgically constructed . following this surgery , the remainder of his childhood and adult life was healthy and normal . on initial examination , he had tachycardia , scleral icterus , a large tender lesion on anterior chest wall , bilateral tender inguinal lymphadenopathy , tenderness on pubic symphysis and right iliac bone , and numbness over his thighs . he was evaluated with various imaging modalities and procedures to come to a final diagnosis . imaging by computed tomography ( ct ) scan revealed innumerable pulmonary nodules , multifocal hepatic lesions , inguinal and retroperitoneal lymphadenopathy , an ill - defined mass in the anterior lower pelvis [ figure 1 ] , as well as multiple lytic lesions in the pelvis . a liver biopsy was performed , results of which showed metastatic adenocarcinoma , positive for ck-7 , ck-20 , and moc-31 . tissue biopsy of the left inguinal node revealed a moderately differentiated adenocarcinoma that was strongly positive for ck-8/18/19 , cam 5.2 , ck-20 , ck-19 , and beta - catenin , suggestive of gastrointestinal or pancreatobiliary adenocarcinoma [ figure 2 ] . due to these findings , an ercp ( endoscopic retrograde cholangiopancreatography ) was warranted which showed a malignant appearing biliary stricture in the proximal bile duct . although this appeared to be the likely primary of the cancer , a testicular ultrasound was ordered to rule out any germ cell tumors and the results came back normal . at this time , various tumor markers were drawn , including cea , afp , and ca 19 - 9 ; levels came back as 272.5 , 4.8 , and 69 , respectively . although it appeared likely to be from the biliary tract based on the ercp , this was only speculation and did not entirely fit with the tumor markers . large soft tissue extraperitoneal mass on ct scan histology of inguinal lymph node biopsy showing adenocarcinoma with central necrosis a colonoscopy was performed that revealed a 15  20 cm mass in the rectosigmoid colon which was biopsied . his laboratory values were as follows : total bilirubin , 3.9 mg / dl ; direct bilirubin , 1.9 mg / dl ; alkaline phosphatase , 579 iu / l ; ast , 248 iu / l ; alt , 19 iu / l ; t protein , 6.3 g / dl ; and albumin , 2.3 mg / dl . treatment was initiated with radiation to the bone metastasis with 2 to 2.5 gy per fraction for the duration of four weeks . additionally , he was started chemotherapy of folinic acid ( leucovorin ) , fluorouracil ( 5-fu ) , and oxaliplatin ( folfox ) . he has completed three cycles of folfox and has an excellent response to this treatment . metastatic spread of colon cancer is quite predictable , initially through lymphatic vessels followed by hematogenous route . rare sites for metastasis are central nervous system ( cns ) , bone , kidney , testis , uterus , and oral cavity . however , hilar lymph nodes , skin , muscles , and adrenal gland are very rare sites , and metastases to these sites are a feature of end - stage widespread disease.[14 ] occasional case reports of metastasis to other organs like pancreas , maxillary sinus , thyroid , knee synovium , larynx , calf , and thigh have been described . unusual spread to axillary nodes , retroperitoneum , heart , subcutaneous tissue , cerebrum , chin , and bladder has also been reported.[1510 ] there have been case reports describing isolated colon cancer metastasis to spleen , adrenal glands , and cutaneous tissue.[1113 ] the lymphatic drainage from the entire colon and proximal two - third of the rectum is into para - aortic lymph nodes , which then drain into the cisterna chyli . it is very uncommon for colon cancers to metastasize to groin nodes , as arterial drainage also does not run toward the external iliac system , and therefore , anatomically , they are not likely to spread to the superficial and deep inguinal lymph nodes . superficial inguinal lymph nodes receive afferent superficial lymphatics from lower extremities , scrotum , penis , vulva , clitoris , anus , and infraumbilical region of the anterior abdominal wall . the deep inguinal lymph nodes receive afferents from superficial inguinal nodes and deep lymphatic trunks associated with femoral vessels . hence , the tumors that metastasize to inguinal lymph nodes are malignant lymphoma , squamous cell carcinoma of vulva , and penis . malignant tumors of skin like malignant melanoma and squamous cell carcinoma of legs or trunk may metastasize to inguinal lymph nodes . the most common gastrointestinal tumor to metastasize to inguinal nodes is squamous cell carcinoma of anal canal . in this case nevertheless , there is a high probability of the metastasis from colon to the inguinal lymph nodes due to postsurgical vascular formations from colon to these lymph nodes , causing such an unusual spread of a colon carcinoma to inguinal lymph nodes . another possible explanation could be due to involvement of the adjacent anterior abdominal wall by micrometastasis from the tumor and therefore the inguinal lymph nodes . this case emphasizes the fact that colorectal cancer metastasizes to unusual sites and should be considered as differential diagnosis for adenocarcinoma of unknown primary . a history of surgery in past increase chances of metastasis to unusual sites due to postsurgical vascular formations .
we present a case of adenocarcinoma of colon with unusual metastasis to inguinal lymph nodes . 
 our patient is a young male with bilateral inguinal lymphadenopathy , bone pains , and jaundice who presented as carcinoma of unknown primary . 
 he was diagnosed as widely metastatic adenocarcinoma of colon for which he received chemotherapy and has had a good response to the treatment .