metastatic squamous cell carcinoma ( scc ) of the colon is rare , but colonic metastases 
 from primary tumors of the lung , esophagus and uterine cervix have been reported [ 14 ] .
carcinoma of unknown primary site is a well - recognized clinical disorder , 
 accounting for 35% of all malignant epithelial tumors .
scc is the most common histologic type of 
 carcinoma of unknown primary site found in cervical lymph nodes [ 1,2 , ] .
however , it 
 is extremely rare for carcinoma of unknown primary site to metastasize to the 
 gastrointestinal tract .
we describe a case of synchronous metastatic scc in the colon 
 and cervical lymph nodes from a carcinoma of unknown primary site .
a 75-year - old woman with a mass in the left submandibular region consulted the 
 department of otorhinolaryngology .
she required assistance in everyday life because of 
 chronic rheumatoid arthritis and a previous cerebral hemorrhage .
fine - needle aspiration 
 showed class v cytology , but the exact histologic type was unclear . left submandibular 
 gland resection with cervical lymph node dissection was performed .
histological examination 
 showed poorly differentiated scc in the lymph nodes located at level ii ( fig .
the patient was considered to have a 
 carcinoma of unknown primary site because no primary lesions were found on detailed 
 examinations of the esophagus , lung , uterine cervix and skin . a preoperative computed 
 tomographic ( ct ) scan showed a small lesion with contrast effect in the transverse 
 colon , which was difficult to distinguish from inflammation .
three months after 
 operation , it was noted that the colonic lesion had grown considerably ( fig .
fluorodeoxyglucose positron 
 emission tomography  showed abnormal uptake in the transverse colon , but there 
 was no accumulation at other sites ( fig .
the specimen shows poorly differentiated scc similar to that 
 seen in the cervical lymph nodes ( h&e stain ,  40 ) . 

figure 2:a preoperative  ct scan showed a small lesion with contrast effect in 
 the transverse colon , which was difficult to distinguish from inflammation 
 ( a ) .
three months after operation , it was noted that the 
 colonic lesion had grown considerably ( b ) . 

figure 3:fluorine-18 fluorodeoxyglucose positron emission tomographic  scan shows 
 positive findings in the transverse colon , with no other positive lesions .
the specimen shows poorly differentiated scc similar to that 
 seen in the cervical lymph nodes ( h&e stain ,  40 ) .
a preoperative  ct scan showed a small lesion with contrast effect in 
 the transverse colon , which was difficult to distinguish from inflammation 
 ( a ) .
three months after operation , it was noted that the 
 colonic lesion had grown considerably ( b ) .
fluorine-18 fluorodeoxyglucose positron emission tomographic  scan shows 
 positive findings in the transverse colon , with no other positive lesions .
colonoscopy revealed a 40-mm submucosal tumor with an inflamed surface in the transverse 
 colon .
the appearance of this lesion suggested a metastatic lesion from another site , 
 and biopsy was performed , but did not provide a definitive diagnosis ( fig .
histological examination of the resected specimen showed features of poorly 
 differentiated scc , similar to that previously seen in the cervical lymph nodes ( fig . 

figure 4:colonoscopy reveals a 40-mm submucosal tumor with an inflamed surface in the 
 transverse colon .
chromoendoscopy shows a tumor covered with normal mucosa . 
 this lesion was a solid mass with a negative cushion sign ( pressure applied to 
 the tumor with a closed pair of biopsy forceps ) .
colonoscopy reveals a 40-mm submucosal tumor with an inflamed surface in the 
 transverse colon .
chromoendoscopy shows a tumor covered with normal mucosa . 
 this lesion was a solid mass with a negative cushion sign ( pressure applied to 
 the tumor with a closed pair of biopsy forceps ) .
the lesion seen in the transverse colon on preoperative ct scans was in fact a small 
 metastatic scc .
this report documents the clinical course of a patient with synchronous 
 metastatic scc to the colon and cervical lymph nodes from a carcinoma of unknown primary 
 site .
this patient demonstrates two important clinical issues : ( i ) carcinoma of unknown 
 primary site can present as colonic metastasis and ( ii ) colonoscopy is useful for 
 establishing the diagnosis .
first , carcinoma of unknown primary site can present with 
 synchronous metastatic scc to the colon and cervical lymph nodes .
scc from an unknown 
 primary lesion with cervical lymph node involvement is found in ~5% of all head 
 and neck cancers .
treatment of patients who have metastatic scc with cervical 
 lymph node involvement from a carcinoma of unknown primary site should be similar to 
 that given to patients with locally advanced carcinoma .
visceral metastases from a carcinoma of unknown primary site are rare and generally have 
 poor prognoses .
the most commonly involved metastatic site is the liver , followed by 
 lymph nodes , lungs , bones and brain .
squamous 
 cell histology is a very rare subset of visceral metastases from carcinoma of unknown 
 primary site .
recently , patients with carcinoma of unknown primary site have been 
 divided into subsets with favorable ( 20% ) and unfavorable ( 80% ) 
 prognoses .
scc involving the cervical lymph nodes is classified as belonging to the 
 favorable subset , whereas colonic metastases belong to the unfavorable subset . in our patient
, synchronous metastatic scc 
 to the colon and cervical lymph nodes was completely resected .
postoperative adjuvant 
 chemoradiotherapy was not given because the patient s general condition was 
 poor .
as of 1.5 years after surgery , the patient is alive with no evidence of 
 recurrence .
the second important clinical feature in our patient is that colonoscopy was useful for 
 diagnosis .
colonic lesions often represent 
 direct invasion from adjacent organs or peritoneal dissemination , but lymphatic and 
 hematogenous metastases from distant organs can also occur .
a submucosal tumor in the 
 gastrointestinal tract is one feature of lesions caused by lymphatic or hematogenous 
 spread from other sites .
endoscopic examination in our patient revealed a gently 
 elevated submucosal tumor with an inflamed surface .
these findings are compatible with 
 colonic metastasis from a carcinoma of unknown primary site .
shimada et al .   reported 
 a synchronous asymptomatic colonic metastasis from a primary esophageal scc .
several 
 reports have documented colonic metastases from the primary scc of the lung . because endoscopic findings differ between epithelial tumor - like lesions and 
 submucosal tumors , colonoscopy was consistently useful for establishing the diagnosis .
a 
 definitive diagnosis was possible after biopsy in some previously reported cases . in conclusion
, we reported a rare case of synchronous metastatic scc to the colon and 
 cervical lymph nodes in a patient with carcinoma of unknown primary site .
 metastatic squamous cell carcinoma ( scc ) from an unknown primary site to the colon 
 has not been reported previously . a 75-year - old woman presented with a mass in the 
 left submandibular region . 
 biopsy revealed a class v lesion , but the histologic type 
 was undetermined . 
 surgical resection of the left submandibular gland with cervical 
 lymph node dissection was performed . 
 however , scc was seen in the lymph nodes only , 
 with no tumor in the submandibular gland . 
 three months after surgery , computed 
 tomography revealed that the preoperatively diagnosed lesion in the transverse colon 
 had grown considerably . a laparoscopic 
 right hemicolectomy was performed . 
 
 histological examination showed features of scc , similar to the findings in the 
 cervical lymph nodes . 
 we report a rare case of synchronous metastatic scc to the 
 colon and cervical lymph nodes from a carcinoma of unknown primary site . 