osteoid osteoma ( oo ) is a benign tumor characterized by a small calcified lesion , usually less than 2 cm in diameter , with nocturnal pain alleviated by the administration of nonsteroidal anti - inflammatory drugs ( nsaids ) .
oo usually affects the long bones and mostly occurs in the first 2 decades of life .
oo arising in the rib is extremely rare , and only 12 cases have been reported in detail to date .
treatment for this tumor is resection of the nidus ; however , difficulty in reaching the nidus through normal tissues increases the invasiveness of the surgical procedure . in the reported cases of rib oos with surgical documentation
we present the first case of oo arising in the rib treated with a computed tomography ( ct)-guided procedure without en bloc resection of the affected rib .
a 20-year - old male complained of nocturnal pain in his left anterior chest which had persisted for 2 years .
conservative treatment was performed for a period of 22 months with administration of nsaids at a nearby hospital .
therefore , he was referred to our hospital for further treatment . at the initial visit to our hospital
a plain radiograph showed bulging and mild bone sclerosis of the left 8th rib ( fig .
ct examinations revealed a well - demarcated 5-mm nidus with peripheral bone sclerosis in this area ( fig .
clinical and radiological findings were compatible with an oo of the left 8th rib . because the patient refused to undergo en bloc rib resection , the operative plan was to perform resection of the nidus under ct guidance .
the operative procedure was performed in the ct room under total anesthesia . after identifying the nidus with a marker ,
a guide pin was inserted by a power drill just adjacent to the edge of the nidus .
a 5.0-mm cannulated drill was inserted over the guide pin to remove the nidus . after removing the lesion , the bone specimen which resided in the cannulated drill
subsequently , heat ablation by an electrosurgical knife using a standard electrosurgical generator was performed to completely destroy any residual tumors .
histopathological studies showed the characteristic appearance of an oo with differentiated osteoblasts lining the osteoid and interconnected trabeculae of woven bone ( fig .
complete pain relief associated with the nidus resection was achieved from the first postoperative day .
the patient was free of pain at the final follow - up after 4 years , and no local recurrence was observed .
oos may affect any bone , but more than half of the tumors occur in the long bones of the lower extremities .
the frequency of oos affecting the ribs is extremely low ( 11.4% ) , with only 12 reported cases with surgical intervention to date [ 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 ] .
conservative treatment consists of nsaid administration for a prolonged period of time , which reportedly leads to alleviation of pain in select cases .
the common principle for operative treatment of oo is thorough resection of the nidus , and incomplete resection could lead to local recurrence .
a complete resection of the nidus by open surgery may lead to further damage of bone and soft tissues around the lesion , when the affected bone is not subcutaneous or when visual localization of the nidus is technically difficult .
although the ribs are easily accessed , the reported lengths of en bloc resection of the nidus ranged from 5 to 9.5 cm , which is significantly wider than the size of the nidus [ 4 , 5 , 6 , 7 ] .
there are reports of varying degrees of functional impairments due to rib resection . in 1990 , voto et al .  
introduced the successful treatment of oos by percutaneous ct - guided resection . over the years
, several percutaneous treatment methods using ct guidance have been introduced : drilling resection , thermocoagulation with radiofrequency , ethanol injection , and a combination of these methods .
however , recurrence rates have been reported to be as high as 1020% , and in cases where the nidus is > 10 mm , these procedures have been reported to be more likely to fail . despite these recurrence rates , a secondary operation either by ct guidance or en bloc resection leads to good results due to the remaining trace left by the primary treatment , enabling minimally invasive en bloc resection .
one drawback of ct - guided resection is that a histological diagnosis may be difficult in some cases , because the resected specimens are small in quantity . by using a cannulated drill and careful curettage
, we were able to make a histological diagnosis in over 90% of the cases ( data not shown ) .
ct - guided percutaneous treatment should be considered as a first - line therapy for oo in the majority of cases , except for lesions difficult to access due to the proximity of vital organs , lesions presenting with atypical findings that are difficult to diagnose as oo , and failed primary ct - guided treatments .
we were able to avoid rib resection without any recurrence of symptoms by the use of a ct - guided resection and heat ablation .
in addition , we were able to obtain enough tissue for histological examination by using a 5.0-mm cannulated drill .
ct - guided procedures should be considered as a treatment of choice for oo of the rib in order to minimize the loss of respiratory function .
informed consent was obtained from the patient for this case report and any accompanying images .
 osteoid osteoma ( oo ) usually occurs in the extremities of young adults . 
 the tumor can arise in any part of the skeletal tissue ; however , it is rarely found in the rib , with limited reports to date . in this report , we present a rare case of oo arising in the rib , which was successfully treated under computed tomography guidance with minimal invasiveness . at the final follow - up after 4 years , no local recurrence was observed . 
Introduction
Case Report
Discussion
Conclusion
Statement of Ethics
Disclosure Statement