lipomasare slow growing fatty tumours of mesenchymal origin and can occur in any organ of the body .
spindlecell lipomas ( scls ) are lipoma variants which have the potential of neuromuscular invasion despite their benign histopathology .       
this case report highlights a spindle cell lipoma variant in the supraclavicular area found intraoperatively to invade both the paravertebral muscles and the brachial plexus .
computerised tomography ( ct ) and magnetic resonance imaging ( mri ) findings were suggestive of possible malignancy but the biopsy and immune - histochemical stains confirmed the diagnosis as scl .        this report highlights the need for making a preoperative diagnosis of spindle cell lipoma .
this ensures accurate patient consent and appropriate preoperative surgical planning including surgical approach and extent of surgery .
a - sixty - three - year - old gentleman presented with a two - year history of a left supraclavicular mass which had increased in size over the previous three months prior to presentation .
he was a smoker with a past medical history of hypertension and type 2 diabetes mellitus .         on examination
, there was a large tennis ball sized swelling in the left neck level v area with no palpable cervical lymphadenopathy .
fine needle aspiration ( fna ) of the mass was performed but it was nondiagnostic .
ct neck showed a 46  69  91  mm left supraclavicular mass posterior to the sternocleidomastoid muscle and superficial to the paravertebral muscles , of fatty density with fine internal septations ( figures 1 and 2 ) .
the radiological appearance was suggestive of a lipoma but a low - grade liposarcoma could not be excluded due to the internal complexity confirmed on mri .
the case was discussed at the multidisciplinary meeting and due to the suspicion of malignancy , and a nondiagnostic fna , excision biopsy was recommended .
the operation was technically difficult because the mass invaginated around the brachial plexus and extended posteriorly through the prevertebral fascia .
complete excision of the mass was undertaken with mobilisation and preservation of the brachial plexus .
histological examination showed mature adipocytes interspersed with fibrous septa containing bland spindle cells with focal pseudo - angiomatous arrangement .
there was the presence of ropey collagen , a very characteristic finding in spindle cell lipoma .
no lipoblasts were seen and the spindle cells showed strong uniform immuno - histochemical positivity for cd34 .           
subsequent review also showed negative staining for cdk4 and p16 , supporting the diagnosis of spindle cell lipoma , and excluding atypical lipomatous neoplasm .
spindle cell lipoma ( scl ) is a benign tumour which typically occurs on the posterior neck , shoulder , or upper back in predominantly elderly males .
there is a marked male predilection especially in the sixth decade which may be partly explained by androgen receptors reactivity .
other rare reported sites of occurrence in the head and neck region include the face , suprasellar region , buccal fat pad , oesophagus , nasal vestibule , the tongue [ 7 , 8 ] , floor of mouth , vallecula   and parotid gland .        
histologically it consists of a proliferation of mature adipocytes , collagen fibres , and spindle cells within a myxoid stroma ( figure 3 , 4 , 5 , 6 , and 7 ) and can infiltrate between skeletal muscle fibres .
on immuno - histochemistry , the spindle cells express cd34 and they are negative for s-100 protein .
they are however desmin negative tumours and this may help differentiate them from other cd34 positive tumours .
differential diagnoses include atypical lipomatous tumour / well - differentiated liposarcoma , pleomorphic lipoma , neurofibroma , nuchal fibroma , lipoblastoma , hibernoma , cellular angiofibroma , extramammary myofibroblastoma , and solitary fibrous tumour .           
it is important to note that reactivity to cd34 immuno - histochemical stain is not specific to only spindle cell lipoma as other entities can demonstrate immunoreactivity to cd34 such as atypical lipomatous neoplasm ( aln)/well - differentiated liposarcoma ( wdl ) .        
aln / wdl is the most common form of liposarcoma seen in late adult life with equal gender affectation generally .
they contain a significant component of mature fat and tend to have less well - defined borders than lipomas .
the favoured sites for aln / wdl are deep soft tissues of extremities and retroperitoneum compared to scl that favour the subcutis of the posterior neck , back and shoulders .           
this coupled with the usual absence of giant marker and ring chromosomes that are typically seen in atypical lipomatous tumour / well - differentiated liposarcoma supports their distinction .                 
immunostaining for mdm2 and cdk4 has been shown to be a relatively sensitive and specific means of identifying and separating atypical lipomatous neoplasm / well - differentiated liposarcoma from various benign lipomatous lesions [ 15 , 16 ] .            in this case report
, histologic findings did not demonstrate sufficient nuclear atypia to suggest a diagnosis of atypical lipomatous tumour and further immuno - histochemical markers that would make such a diagnosis possible ( cdk4 , p16 ) were found to be negative .         
scl shares overlapping clinical , morphologic , and immuno - histochemical findings with pleomorphic lipoma as well as the same cytogenetic aberrations .
it however typically arises in the dermis , often in younger patients and lacks the characteristic ropey collagen of scl .           
schwannoma and neurofibroma have a similar striking nuclear palisading and conspicuous mast cell infiltrate present in some scl .
scl may also be mistaken for several sarcomas , including myxoid liposarcoma or spindle cell liposarcoma .
the presence of multinucleated floret - like giant cells is characteristic of pleomorphic lipoma and is occasionally seen in atypical lipomatous tumour / well - differentiated liposarcoma .             in this case report , the spindle cell lipoma presented a diagnostic and management dilemma as it could not be clinically differentiated from a liposarcoma which would require a more radical approach to treatment .
the radiologic findings of a complex internal architecture with fine septations allowed differentiation of the preoperative differential diagnosis from a benign lipoma or possible malignancy but could not differentiate between a liposarcoma or a spindle cell lipoma .        
the authors suggest that when radiologic findings suggest a complex internal architecture suspicious for a diagnosis of a possible lipomatous tumour , it is imperative to obtain a biopsy prior to definitive surgery .
histologic interpretation is crucial and this can be supported by the use of immune - histochemical stains .
immuno - histochemical stains demonstrating positivity for cd34 can be helpful in diagnosis of cd34 positive tumours such as spindle cell lipoma , and the differential diagnoses discussed such as atypical lipomatous tumour and dermatofibrosarcoma protuberans ( dfsp ) .
as discussed , further differentiation can be made based on clinical presentation , immunoreactivity for actin or desmin , s-100 protein staining of mature lipocytes , the presence / absence of ropey collagen bundles , multinucleated floret - like giant cells and cytogenetic aberrations . in difficult cases ,
a preoperative diagnosis of spindle cell lipoma is crucial to surgical management as it impacts on the consent process , surgical approach , extent of surgery , and management .         in making a preoperative diagnosis ,
however , it is important to note that fna may be nondiagnostic as it was in this case , because the specimen consisted largely of fatty cells .
core biopsy is preferable and can be obtained by an initial procedure under anaesthesia prior to definitive surgery based on a histological diagnosis .  
a preoperative diagnosis will guide the consent process as such patients can be warned of the risks of neurovascular injury as well as determining the extent of surgery .
 
 background . spindle cell lipoma ( scl ) is a benign lipomatous tumour , typically occurring in the posterior neck , shoulder or upper back of elderly males . 
 they compose of fat , cd34 positive spindle cells , and ropey collagen on a myxoid matrix . 
 
 this case highlights a rare presentation of scl and the need for pre - operative diagnosis . 
 case report . 
 a 63-year - old gentleman presented with a pre - existing left supraclavicular mass that had recently increased in size . 
 fna and ct scans were performed and results discussed in the mutidisciplinary team meeting . 
 excisional biopsy was recommended . 
 radiology . 
 ct neck showed a left supraclavicular mass of fatty density with fine internal septations . 
 a low - grade liposarcoma could not be excluded . 
 histopathology . 
 fna was indeterminate . 
 histology of specimen showed bland spindle cells with no evidence of malignancy . 
 immuno - histochemistry showed scl with cd34 positivity and negative staining on cdk4 and p16 . 
 management . 
 excision biopsy of the mass was performed which was technically difficult as the mass invaginated around the brachial plexus . 
 the patient recovered well post - operatively with no neurological deficits . 
 conclusion . 
 spindle cell lipoma is a rare benign tumour and a pre - operative diagnosis based on the clinical context , imaging and immuno - histochemistry is crucial to management . 
1. Introduction
2. Case Report
3. Pathology
4. Discussion
5. Differential Diagnoses