bednar tumor or pigmented dermatofibrosarcoma protuberans ( dfsp ) is a rare , aggressive , cutaneous tumor that constitutes 1 - 5% of all dfsps .
a 40-year - old female presented with right shoulder swelling present since few months and gradually increasing in size .
a complete excision was performed without any prior fine needle aspiration cytology or needle biopsy .
the tumor was just beneath the skin , fairly circumscribed , non - capsulated extending into the subcutaneous fat and measuring 5  4  4 cm .
grossly , focal areas of pigmentation were noticed towards the periphery of the tumor ( fig .
the tumor was a spindle cell lesion abutting the skin and invading the underlying subcutaneous fat .
2 ) . on higher magnification , the spindle cells were uniform appearing with a moderate amount of eosinophillic cytoplasm and plump nuclei with tapering edges .
the pigment - laden cells showed coarse brown black pigment obscuring the nuclei and positivity for masson - fontana stain .
it is considered to be a tumor of intermediate grade and very infrequently reported in the literature .
it is seen in young to middle - aged adults in the fourth decade with very occasional cases in the pediatric age group .
the preferred sites are the shoulder region as in our case as well as the trunk , extremities and the head and neck .
grossly , the tumors have been described to be multilobular with pigmentation , irregular surface and firm nodules growing deep within the subcutaneous tissue . in this case , the cut surface of the fairly circumscribed tumor showed trabeculations and peculiar pigmentation in the subepidermal portion , which has not been described in the literature .
it has to be distinguished from other pigmented cutaneous spindle cell lesions like pigmented neurofibroma , psammomatous melanotic schwannoma , neurocristic cutaneous hamartoma and desmoplastic malignant melanoma .
however , our case had classic features of dfsp , and the above lesions were ruled out on histopathology itself .
neuro - ectodermal differentiation or melanocytic colonization are the two proposed theories for histogenesis for the bednar tumor .
it has also been reported in association of dermal melanocytosis ( nevus of ito ) , and based on the immunohistochemistry , the cell of origin is thought to be a neuromesenchymal cell .
bednar tumor can rarely undergo malignant transformation in form of fibrosarcoma with repeated recurrences and distant metastasis .
hence , a close follow - up of these cases is always necessary , which is being done in our case . to conclude , though rare , it is important for the histopathologists to be aware and recognize this unusual entity and distinguish it from other pigmented spindle cell lesions .
ethics committee approval and patient consent has been obtained . published research complies with the guidelines for human studies and animal welfare regulations .
the patient has given informed consent , and the study protocol has been approved by the institute 's committee on human research .
 bednar tumor is an uncommon variant of dermatofibrosarcoma protuberans . 
 also known as pigmented dermatofibrosarcoma protuberans , this tumor is of intermediate grade . 
 it is seen in adults and has a predisposition to affect the shoulder region . 
 we report a rare case of bednar tumor in a 40-year - old female patient . 
 the diagnosis of bednar tumor must be considered while reporting pigmented subcutaneous spindle cell lesions . 