pleomorphic lipoma ( pl ) is a rare variant of lipoma on a continuum with spindle lipoma . microscopically , these tumours are composed of mature fat cells mixed with bland spindle cells , hyperchromatic round cells , and multinucleated giant cells . the vast majority of tumours are located in the subcutaneous tissue of the posterior neck and upper back . to best of our knowledge , this is the third cases reported in international literature . a final diagnosis may be difficult because of the prevalence of spindle and multinucleated pleomorphic cells and the presence of abundant myxoid stroma . we add a new illustrative case to the 2 cases of pl of tongue reported in literature . a 44-year - old woman presented with a slow - growing , painless nodule of the tongue with difficulty in deglutition . clinical examination revealed a soft , sub - mucosal nodule , measuring approximately 3 cm in maximum diameter , covered by normal mucosa . a surgical excision was performed . histological examination showed mature adipocytes , diffusely infiltrating striated muscle fibres , [ figure 1 ] and abundant mucoid stroma [ figure 2 ] . in this myxoid background were present bland - appearing spindle cells and multinucleated giant cells with radially arranged nuclei in a the spindle and giant cells were strongly positive for cd34 [ figure 4 ] and negative for s100 . a fluorescence in situ hybridization ( fish ) was performed on formalin - fixed , paraffin - embedded tissue sections using mdm2 ( 12q15 ) dual - colour probe ( vysis , downers grove , il , usa ) . the post - operative course was uneventful ; after 1 year , the patient was free of disease although the tumour was present at the margins of the excised specimen and is currently on follow - up . the mass was poor circumscribed and lipomatous in appearance with mature adipocytes , diffusely infiltrating striated muscle fibers ( h and e ,  10 ) mature adipose tissue was admixed with abundant mucoid stroma ( h and e ,  20 ) mucoid areas showed bland - appearing spindle cells and multinucleated giant cells with radially arranged nuclei in a floret - like  pattern ( h and e ,  20 ) the spindle and giant cells were strongly positive for cd34 ( immunoperoxydase ,  40 ) lipomas are the most common mesenchymal tumours of soft tissue but are uncommon in the oral and maxillofacial region . classic lipoma is the most frequent type in these sites , but other variants have been described including some cases of atypical lipomatous tumour ( alt)/well - differentiated liposarcoma ( wdl ) . pl is a distinctive variant of lipoma originally described by enzinger , characterized by replacement of mature fat by bundle of spindle cells , hyperchromatic round cells and giant cells with floret - like nuclei admixed with dense collagen fibres or within a myxoid stroma . exceptionally , pl have been described in the tongue ; to best of our knowledge , only two case have been reported in literature . the different proportion of fat cells , spindle cells , collagen fibres , and mucoid substance confers to pl a variable macroscopic and microscopic appearance that can hamper the diagnosis . neurofibroma , ancient schwannoma , myxoma , and nodular fasciitis are the lesions that most frequently showed cellular features that overlap with pl . the most difficult differential diagnosis is with alt / well - differentiated liposarcoma ( wdl ) , and with pleomorphic liposarcoma . the presence of infiltrative margins , the identification of  bizarre  multinucleated giant cells with hyperchromatic nuclei , and some lipoblast - like cells may suggest a diagnosis of malignancy . moreover , the floret - like cells of pl are not pathognomonic but may be present also in liposarcomas . unlike the latter , the former lacks of true lipoblasts , cellular pleomorphism , marked vascularisation , mitotic activity , and show an intense immunoreactivity for cd34 . in difficult cases , the combination of immunohistochemistry and ( fish ) that shows the amplification of mdm2 and cdk4 genes may play a role in differential diagnosis with benign adipose tumours . despite the worrisome morphological features , pl is benign , rarely recur , and a possible malignant transformation is not described in literature . in conclusion , pl is a benign lesion that rarely can arise in unusual site as the tongue and is cured by complete local excision . the cytological features and the immunoreactivity for cd34 may suggest a pl addressing a proper surgical procedure .
we herein report a rare case of pleomorphic lipoma of the tongue with a review of world literature . 
 a 44-year - old woman presented with a nodule of the tongue that had been present for over three years . clinical examination revealed a yellowish sub - mucosal lesion , measuring 3 cm in maximum diameter , protruding from lingual surface . 
 a first biopsy showed a lipomatous tumour composed of mature adipocytes intermingled with myxoid areas composed of spindle uniform in size and shape and multinucleated floret - like giant cells . 
 spindle and giant cells were positive for cd34 . 
 a diagnosis of pleomorphic lipoma was made . in view of the benign nature of this mass , it was de - bulked rather than completely excised in order to preserve swallowing function .