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angiolipoma ( al ) is a relatively rare tumor of the head and neck region , although it occurs more commonly in the forearm and the trunk regions .
this tumor has been rarely reported in the oral cavity , and to best of our knowledge , it has only been reported twice in the lip .
the histological characteristics of angiolipoma are a mixture of mature adipocytes and interspersed connective tissues with vascular vessels containing fibrin thrombi and mast cell infiltration , which are distinct from usual lipomas .
we present , a rare case of non - infiltrating angiolipoma occurring on the upper lip in a 9-year - old female .
a 9-year - old female presented with an asymptomatic swelling of upper lip since birth .
she complained of a slight increase in size of swelling for the past 1 month .
clinical examination revealed a swelling of 2  2 cm in diameter at the midline of the upper lip [ figure 1 ] .
swelling was well circumscribed , soft in consistency , movable , non - tender , non - fluctuant , and no bruit was present .
the mass was dissected free of the adjacent tissue and the lesion was surgically removed under local anesthesia . on gross examination ,
the mass was multilobulated , grayish white in color , soft in consistency and measuring about 2  2 cm in diameter [ figure 2 ] .
clinical photograph of patient gross specimen showing multilobulated mass histopathologically , h and e stained section under low magnification revealed an encapsulated tumor mass consisting of adipose tissue separated by branched vascular network [ figure 3 ] .
thin walled small capillary like vessels were present at the periphery of the tumor mass [ figure 4 ] . under higher magnification
numerous mature adipocytes with variable sized endothelial lined blood vessels were seen [ figure 5 ] .
toluidine blue staining showed an increased mast cells density in and around blood vessels [ figure 7 ] with degranulation [ figure 8 ] .
. encapsulated tumor mass consisting of adipose tissue separated by branched vascular network ( h and e stain , original magnification , 10 ) numerous mature adipocytes with variable sized endothelial lined blood vessels ( h and e stain , original magnification , 10 ) thin walled capillary like vessels present at the periphery of the tumor mass ( h and e stain , original magnification , 40 ) presence of fibrinous microthrombi ( h and e stain , original magnification , 40 ) tumor tissue showing increased mast cells density in and around blood vessels ( toluidine blue stain , original magnification 40 ) tumor tissue showing degranulating mast cell in and around blood vessels ( toluidine blue stain , original magnification 40 )
it is widely assumed that benign lipomatous tumors represent a common group of neoplasm 's that cause few complaints or complications and present little diagnostic difficulty .
. thirteen percent of all lipomas occur in head and neck , including cheek , tongue , palate , parotid gland , neck and larynx .
they are usually asymptomatic , slow - growing , soft and well - circumscribed submucosal or superficial lesion , mainly located on the buccal mucosa .
the bulk of lipomatous tumors may be grouped into four categories : superficial lipoma , a tumor composed of mature fat and arising in the superficial ( subcutaneous ) soft tissues , represents by far the most common mesenchymal neoplasm .
deep lipomas arise from or are intimately associated with tissues deep to the subcutis or with specific anatomic sites .
the main subdivisions of this group are angiomyolipoma , intramuscular and intermuscular lipoma , lipoma of the tendon sheath , neural fibrolipoma with or without macrodactyly and lumbosacral lipoma .
infiltrating or diffuse neoplastic or non - neoplastic proliferations of mature fat may cause compression of vital structures or may be confused with atypical lipomatous neoplasm / well - differentiated liposarcoma .
this group is composed of six entities : diffuse lipomatosis , pelvic lipomatosis , symmetric lipomatosis , adiposis dolorosa , steroid lipomatosis , and nevus lipomatosus .
variants of lipoma are much less common and differ from ordinary lipoma by characteristic microscopic picture and specific clinical setting .
these include angiolipoma ( al ) , myolipoma , angiomyolipoma , myelolipoma , chondroid lipoma , spindle cell / pleomorphic lipoma , hibernoma and lipoblastoma / lipoblastomatosis .
al is a benign mesenchymal tumor made up of mature lipocytes and proliferating blood vessels .
they are benign subcutaneous lesions most common in young male patients in their second or third decades of life
. they can be multiple in nature , and are most commonly seen on forearm ( two - third of cases ) followed by the trunk and upper arm .
only 38 cases of head and neck als have been reported . to the best of our knowledge
there are only two cases of al of the lip reported in the english literature . when seen in the oral cavity ,
it has been noted to be on the lip , tongue , palatal tissue , cheek being the most common site . in a review of al of head and neck , alvi et al . mentioned certain distinct characteristics which are present between head and neck al and non - head and neck al [ table 1 ] .
characteristics of hand neck versus non - head and neck al differential diagnosis of a soft mobile mass in the head and neck , and especially in the upper lip , should alert the clinician to consider other entities such as canalicular adenoma , basal cell adenoma , pleomorphic adenoma , angioleiomyoma , schwannoma , neurofibroma , other benign mesenchymal tumors and xanthogranuloma .
different theories suggest that a lipoma differentiates because of some unknown stimulus ; the tumor is of neurogenic origin ; and it is congenital .
possible causes include fatty metamorphosis of a central hemangioma , hyperplasia of fat with an associated increase in vascular channels , or a true neoplasm .
there is support for the theory that an al originates as a congenital lipoma , which later undergoes vascular proliferation .
howard and helwig think that embryonic sequestration of multipotential cells become activated at puberty by hormones and differentiate into a simple lipoma .
further stimuli such as trauma can cause vascular infiltration of the lesion , but trauma is not present in many cases of al .
it has been speculated that mast cells might play a role in their increased vascularity .
mast cells around blood vessels strongly express vascular endothelial growth factor ( vegf ) in angiolipoma , which is known to be an essential growth factor for endothelial cells in angiogenesis . in the present case ,
toluidine blue staining showed an increased mast cells density around blood vessels , with degranulation , speculating its role in vasculogenesis .
however , there has been no direct demonstration of molecular mechanisms for angiogenesis participation by mast cells in angiolipoma . based on studies by gonzales - crussi et al .
it presents as painless or tender subcutaneous nodules , generally in pubescent patients and is rare before puberty .
histologically it is encapsulated , and is a mixture of mature adipocytes and a proliferation of thin - walled vascular channels .
they extend into the surrounding tissue and are characterized by a non - encapsulated tumor mass .
the present case was that of non - infiltrating al of 2  2 cm in diameter located in the upper lip of young female .
following are the current histologic guidelines for diagnosis of al : 
 well encapsulated ( non - infiltrating als ) or poorly encapsulated ( infiltrating als).evidence of 50% mature adipocytes in the tumor.interspersed angiomatous proliferation in the tumor.fibrinous microthrombi.absence of other mesenchymal elements ( smooth muscle ) or pleomorphism . 
  well encapsulated ( non - infiltrating als ) or poorly encapsulated ( infiltrating als ) . evidence of 50% mature adipocytes in the tumor . interspersed angiomatous proliferation in the tumor .
histopathological differential diagnosis includes hemangioma , lipoma , angiomyolipoma , infiltrating lipoma , angiofibrolipoma , angiomyxolipoma , and liposarcoma .
angiomyolipoma is composed of varying amounts of blood vessels , smooth muscles and fat cells .
infiltrating lipoma consists of lesional fat tissue infiltrating in the deeper tissue , in the form of long thin streaks radiating from the intratumoral mass .
angiofibrolipoma is composed of varying amounts of blood vessels , fibrous tissue and fat cells .
it is the most common benign tumor of the kidney and is strongly associated with tuberous sclerosis .
the hypovascular lesions may be difficult to distinguish from ordinary lipomas , although the identification of microthrombi allows this distinction .
liposarcoma can be confused with al but can usually be differentiated by the presence of embryonal adipose tissue , pleomorphism , increased number of mitosis , and metastasis . the al has not been shown to spontaneously regress and has been shown to continue to enlarge as opposed to other entities such as a hemangioma .
the treatment of choice for a non - infiltrating al is surgical excision , whereas a wide local excision with free margins has been advocated for the infiltrating type . in the case of inadequate resection
the recurrence of al has been reported to be dependent on whether the mass is infiltrating . infiltrating als have been reported to be more common in an older age group .
their recurrence has been reported to be as high as 62.5% in areas outside the head and neck .
noninfiltrating types are seen more commonly in a younger age group and have no tendency to recur . a successful treatment of a giant infiltrating angiolipoma with interferon alfa also has been reported .
in conclusion , lipomas represent about 1%4% of all neoplasm 's of the oral cavity .
they are usually asymptomatic , slow - growing , soft and well - circumscribed submucosal or superficial lesion .
it consists of mature adipocytes and interspersed connective tissues with vascular vessels containing fibrin thrombi and mast cell infiltration .
wide surgical excision with free margins is the treatment of choice , offering a good prognosis and an almost negligible relapse rate .
angiolipoma is a variant of lipoma with a prominent vascular component . 
 it is the most common tumor of the forearm followed by trunk and extremities of young individuals . 
 it 's occurrence in head and neck region is rare . in this report 
 , we present clinical and histopathologic features of non - infiltrating angiolipoma occurring on the upper lip in a 9-year - old female . 
 toluidine blue stain is used to demonstrate increased mast cell density around blood vessels , speculating its role in vasculogenesis .