lipoma is the most common benign neoplasm of mesenchymal origin , and it is composed of mature adipose tissue without cellular atypia . though predominantly located in subcutaneous sites , they are also found intramuscularly , retroperitoneally , and in intraosseous locations . osseous lipomas are very rare despite the large amount of fatty marrow in the adult . they most commonly occur in the calcaneus and long bones of lower extremities . depending upon the location in relation to bone , they may be intraosseous ( intramedullary and intracortical ) or juxtacortical ( parosteal and subperiosteal ) . the occasional symptomatic case may be present with swelling and rarely with pain . in this article , we are reporting a case of intraosseous lipoma of the mandible , which to the best of our knowledge is the fifth only reported case in anterior mandible . also , significant is its presentation as a swelling , which is very rare for an intraosseous lipoma ( iol ) in the jaw bones . a 15-year - old boy reported to our institution with a complaint of swelling in the right lower jaw of 2 years duration , associated with increasing difficulty in speech . intraoral examination revealed a smooth , non tender , and bony hard , ovoid swelling of about 4  2.5 cm size , located towards the lingual aspect of mandible extending from 41 to 47 [ figure 1 ] . the pre - operative view shows a smooth , ovoid swelling on the lingual aspect of the mandible extending from mesial of 41 to 47 a mandibular occlusal radiograph revealed cortical expansion with hazy radiopacity on the lingual surface of mandible [ figure 2 ] . cross - sectional mandibular occlusal radiograph shows cortical expansion with hazy radiopacity on the lingual surface of mandible extending from 41 to 47 region the specimen was decalcified overnight in 8% nitric acid and routinely processed to obtain paraffin - embedded , 10  thick hematoxylin and eosin ( h and e ) stained slides . microscopically , the tissue was composed of areas of mature adipocytes interspersed with few trabeculae of mature lamellated bone and prominent thin - walled , large caliber vascular spaces . the major part of the lesion was surrounded by a continuous layer of cortical bone , which appeared to be thinned out [ figure 4 ] . ( h and e , stain ; 100 original magnification ) photomicrograph showing thinned out cortical bone present at the periphery of the lesion ( h and e , 100 original magnification ) based on these findings , a diagnosis of intraosseous lipoma was made . iol is one of the rarest bone tumors accounting for approximately 0.1% of all benign primary bone tumors . the first case of iol was described in 1880 by cornil and ranvier in the femur . nearly every bone can be affected by this tumor , although favored sites are the calcaneus and the metaphysis of long bones . these adipocyte tumors occur most commonly in the fourth decade with a slight male predilection . symptoms , when present , are localized mild pain , swelling or rarely fracture of the affected bone . based on their location , osseous lipomas can be intraosseous ( intramedullary and intracortical ) and juxtacortical ( parosteal and subperiosteal ) . the only two reported cases of intracortical lipoma were seen in the diaphysis of long bones , as well - demarcated radiolucent areas not communicating with the medullary cavity . a total of 24 cases of intramedullary lipomas have been reported in the jaw bones till date . of these , only four have occurred in the anterior mandible , our case thus being the fifth . although clinical examination combined with computed tomography ( ct ) or magnetic resonance imaging ( mri ) can point towards iol , a definitive diagnosis requires microscopic examination . microscopically , sheets of mature adipocytes without atypia and absence of hematopoietic elements are the essential features . based on the level of involution , three stages of intraosseous lipomas have been described by milgram : stage 1 , when there is no secondary necrosis ; stage 2 , when there is partial necrosis ; stage 3 , when there is complete secondary necrosis and dystrophic calcification . since we did not find areas of necrosis or dystrophic calcification in the present case , we considered it was in stage 1 of milgram 's staging . microscopically , the lesion must be distinguished from a well - differentiated liposarcoma , normal fibro - fatty bone marrow , and osteoporotic bone marrow defect . diagnosis of normal fibro - fatty bone marrow was ruled out because of the lack of hematopoietic tissue and the expansile nature of the lesion . furthermore , absence of any history of previous trauma to the site excluded the possibility of an osteoporotic bone marrow defect . others have proposed that iol are reactive changes secondary to infarcts , infections , or trauma . another hypothesis is that they are simple conglomerations of fatty marrow , formed as part of the normal ageing bone process . however , in the present case , the young age of the patient and the absence of any trauma to the region , all point towards a benign neoplastic nature of the lesion . in symptomatic lesions and those prone to undergo pathologic fracture , curettage is the treatment of choice . recurrence of the intraosseous lipoma is rare and it has been reported in only two cases . though intraosseous lipomas are considered benign , milgram reported four cases of malignant transformation ; however , no recurrence or malignant changes of mandibular intraosseous lipomas have been reported . though , reported cases of osseous lipomas of the jaws are very few in number , this case highlights the importance of including it in the differential diagnosis of jaw lesions and properly documenting each new case .