atypical fibroxanthoma ( afx ) is a malignancy developed typically in the dermis of the head and neck of senior caucasians , however it is a very rare tumor in asians [ 1 - 5 ] .
in addition , the incidence of afx in koreans is very low and only 6 cases developed in the sun - exposed face and hand area have been reported in dermatology [ 6 - 10 ] . although the metastatic potential is known to be low , it grows rapidly and has a highly local recurrent ability . it must be differentiated from many diseases since it shows the sarcoma pattern consisting of atypical spindle cells within the dermis histology .
it can also be considered a benign lesion because there is no pain or local invasion clinically . although rare , metastases have been reported , and they could not be differentiated from malignant fibrous histiocytoma ( mfh ) histopathologically . as a treatment ,
however , local recurrence can occur frequently because the margin is not distinct when performing an excision .
therefore , a wide excision has been known to be the most effective . in this study , we examine a case diagnosed as atypical fibroxanthoma in the head and neck area , and report this case with a review of the literature .
our patient was a 70-year - old male who 3 months ago underwent an incision biopsy at another hospital for a 1.01.0 cm sized palpable and protruding reddish nodule in the left infra - auricular area . by result of a histological test ,
a malignant tumor was suspected and he was transferred to our hospital . in the physical examination , there was a round scar remaining from the previously performed biopsy and the size of the resected tissue was approximately 0.70.7 cm .
the specimen acquired at the other hospital was examined again at our hospital . in our histopathologic
finding , we detected a numerously mitotic figure with atypical , bizarre , large and hyperchromatic nuclei ( fig .
, we had cd34 , cd45 , cytokeratin and desmin showing negative reaction with a positive reaction for vimentin as well as cd68 .
in addition , the malignancy was confirmed in the previous incision margin , and there was no special findings in a metastatic work - up .
therefore , a wide excision was performed with 2 cm safety resection margin around the lesion which underwent the initial incision biopsy , and there was no malignancy detected by frozen biopsy ( fig .
twelve months have passed after surgery and the patient is under the follow - up observation at our outpatient clinic without any local recurrence .
an afx is a rapid growing neoplasm with low metastatic potential , but local recurrence is estimated at between 2%-20% and metastasis has been reported .
it is a solitary nodule smaller than 2 cm in diameter in most cases and it occurs on the face as well as the back of the hand in caucasians older than 50 years ( average , 70-year - old ) in the sun - exposed area [ 1 - 5 ] .
it is thought that the length of sun exposure , trauma and previous cutaneous neoplasm history as well as previous radiation history are all involved in the risk factors in the development of afx .
histopathologically , it commonly accompanies ulceration in the epidermis covering the lesion and there is a partial protrusion shape compared with adjacent tissue .
pleomorphic tumors with an indistinct border adjacent to the dermis - epidermis junction are shown .
tumor cells are primarily atypical spindle cells , multinucleated giant cells with a strange shape that can not be characterized and are also mixed with pleomorphic cells .
many mitosis are observed and cells similar to fibroxanthoma are densely distributed and surround the skin adnexa . with immunohistochemical staining , it is positive for vimentin .
however , it shows negative for cd34 , cytokeratin , desmin , and s-100 protein [ 1 - 5 ] .
diseases to be differentiated are dermatofibrosarcoma protuberance ( dfsp ) , mfh , leiomyosarcoma , spindle cell cancer , squamous cell carcinoma , etc . from the aspect of clinical findings ,
, mfh is similar to afx , however mfh occurs preferentially in the limbs and deep invasion is frequent which is different from afx .
there is also a positive result for vimentin , and a negative result for cd34 and s-100 protein .
leimyosarcoma or squamous cell tumors could be differentiated by histologic findings as well as immunohistochemistry test .
recently , the expression of cd99 and s-100a6 has been reported to be a useful immunohistochemical test indicator for the diagnosis of afx .
regarding afx treatments , although the tumor shows histological malignancy findings , the site of the lesion is the superficial layer in most cases , and the tumor shows a benign course since its metastatic potential is low . it could be treated by complete resection with 2 cm safety resection margin creating a good prognosis .
however , in the case of a large tumor or a tumor lacking a distinctive border , the recurrence and metastasis are more frequent .
our patient had a mass developed in the infra - auricular area which looked like a benign nodule and underwent an incision biopsy .
since it was diagnosed as an atypical fibroxanthoma in the histopathologic test , a complete resection was done with 2 cm safe margin around the initial lesion .
the postsurgical follow - up observation period was just 1 year , which may be short for malignant tumor case .
therefore we think we can check the recurrence status every three months for a 2 year period . in my opinion ,
typically , in this case , a simple incision biopsy is preferred because of the simplicity of surgery and less discomfort to the patients . however , we believe it needs to be an excisional biopsy even if it is a simple nodule , because it may give rise to more serious problem and we can not completely exclude the possibility of malignant tumor .
we think this case is very important because , it is not only a rare case in a korean , but also consider the question of the diagnosis of a neck mass once more . as a result , we report this case together with a review of the literature .
 atypical fibroxanthoma is a pleomorphic spindle cell tumor of the dermis and it 's been known to be a benign lesion clinically in spite of malignant histologic features . 
 but recurrence is estimated at between 2%-20% and metastasis has been reported . 
 we are about to describe a 70-year - old man with the lesion developed on the left infra - auricular area . 
 the lesion was located superficially and is composed of compact pleomorphic spindle cells and several bizarre multinucleated giant cells . 
 the patient was treated with wide excision . 
 we would like to discuss about this case with a review of literatures . 
INTRODUCTION
CASE REPORT
DISCUSSION