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E-IJD CORRESPONDENCE
Year : 2015  |  Volume : 60  |  Issue : 1  |  Page : 107
Variant of dermatofibrosarcoma protuberans: Bednar tumor


1 Department of Pathology, Dr. Rajendra Prasad Government Medical College, Tanda, Himachal Pradesh, India
2 Department of ENT, Dr. Rajendra Prasad Government Medical College, Tanda, Himachal Pradesh, India

Date of Web Publication26-Dec-2014

Correspondence Address:
Rashmi Kaul
Department of Pathology, Dr. Rajendra Prasad Government Medical College, Tanda, Himachal Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0019-5154.147885

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How to cite this article:
Kaul R, Kaur N, Dogra SS, Chander B. Variant of dermatofibrosarcoma protuberans: Bednar tumor. Indian J Dermatol 2015;60:107

How to cite this URL:
Kaul R, Kaur N, Dogra SS, Chander B. Variant of dermatofibrosarcoma protuberans: Bednar tumor. Indian J Dermatol [serial online] 2015 [cited 2020 Sep 23];60:107. Available from: http://www.e-ijd.org/text.asp?2015/60/1/107/147885


Sir,

Bednar tumor is a rare variant of dermatofibrosarcoma protuberans with melanin pigment in cells. This tumor is of unexplained histogenesis but it may be related to remnants of embryonic mammary tissue or to various kinds of local trauma such as burns, vaccination scars and insect bites. The biological behavior is that of intermediate malignancy. Histologically, it comprises of spindle cells with mild pleomorphism. Immunohistochemically the cells are CD34 positive. In this report, we present this patient who presented with recurrent postauricular swelling, which was resected twice in the last 5 years. This lesion was diagnosed as Bednar tumor.

A 52-year-old man had a small nodular swelling behind his right pinna for last 5 years. The swelling was excised twice in the past with recurrence. The histopathological records were not available. The patient now presented to us with postauricular swelling which was 5×3×3 cms, grayish black in color, multinodular, nontender, not fixed to the underlying tissue and slightly mobile [Figure 1]. There were no satellite lesions. A fine-needle aspiration of the lesion was performed and Giemsa staining done. The cytologic features revealed a spindle cell lesion with obscuring pigment. The tumor was resected along with fascia and a clinically tumor-free margin. The histopathologic examination revealed proliferating spindle cells arranged in storiform pattern, with mild pleomorphism, inconspicuous nucleoli and mild to moderate mitotic activity. The overlying skin was free. The pleomorphic cells were seen infiltrating into the underlying dermis around appendages and into the subcutaneous tissue. The cells were seen containing blackish pigment in varying proportions [Figure 2]. Negative results of iron stains were obtained. Areas of hemorrhage and necrosis could be seen. The immunohistochemistry showed positivity for CD34. A final diagnosis of Bednar tumor was made. The patient is on follow up for the last 6 months without any evidence of recurrence.
Figure 1: Photograph showing a postauricular multinodular, grayish-blue soft tissue mass

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Figure 2: Photomicrograph showing pleomorphic spindle cells and intra/extracellular pigment (H and E X40)

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Bednar tumor was first described in 1957 and is considered to be a rare variant of dermatofibrosarcoma protuberans (DFSP). [1] Its incidence is approximately 1-5% of all cases of DFSP. [2] The knowledge of this tumor of the skin is important, because on histological examination these tumors can easily be mistaken for fibrosarcoma and melanoma. Bednar tumor occurs mainly in early adulthood or middle age, however, they may also occur in infancy, and men and women are equally affected. The common site of origin is the trunk, especially the back and shoulders. Most tumors present as slow-growing, wide-based, protruding masses or plaques in the dermis and subcutaneous tissue. Bednar tumor is considered to be of intermediate malignancy, but it tends to have frequent local recurrences and a long follow up is required. [3] Metastasis is rare and late and dissemination may occur via the hematogenous route and rarely lymphatic. The principle sites of metastasis are lungs, bones, liver, pancreas, stomach, intestine, thyroid and brain. [4]

The treatment of choice for Bednar tumor is Mohs micrographic surgery. With surgical margins of 3 cm, the recurrence rate is 20% and with margins less than 2 cm, it is 40% so a minimal margin of 3 cm with inclusion of superficial fascia is recommended to minimize the risk of recurrence. [5]

Bednar tumor consists of spindle-shaped cells resembling fibroblasts and other melanin-containing dendritic cells. The origin of the tumor cells and the histogenesis have not been fully determined and are controversial, but many authors have suggested that Bednar tumor is derived from neuroectodermal cells on the basis of ultrastructural and immunohistological findings and the presence of melanosome-containing cells. [1],[2],[3],[6] Lesions often appear black due to the large amount of melanin present. In nonpigmented lesions, melanin has been documented only on microscopic examination. [2],[4]

The differential diagnosis of Bednar tumor includes fibrous histiocytoma, neurofibroma, malignant melanoma, and cellular blue nevus. They almost always contain immunoreactive S-100 protein. On the other hand, DFSP and Bednar tumor do not always stain for S-100 protein, but CD34 antigen is present in both tumors, and the latter tumor also contains dendritic melanin-bearing cells. [2] CD34 has been considered to be the most useful marker for distinguishing DFSP from other fibrohistiocytic tumors such as dermatofibroma, malignant fibrous histiocytoma, and scar tissue. [6]

In conclusion, complete extirpation with close follow-up care is indicated for this neoplasm although metastases are rare. The recommended treatment is wide excision with 3 cm margins of visibly uninvolved tissue and inclusion of superficial fascia. Because of its rarity, information is lacking regarding the optimal therapy and potential utility of immunohistochemistry in diagnosis, so further investigation is needed.

 
   References Top

1.
Bednar B. Storiform neurofibromas of the skin, pigmented and nonpigmented. Cancer 1957;10:368-76.  Back to cited text no. 1
    
2.
Dupree WB, Langloss JM, Weiss SW. Pigmented dermatofibrosarcoma protuberans (Bednar tumor): A pathologic, ultrastructural, and immunohistochemical study. Am J Surg Pathol 1985;9:630-9.  Back to cited text no. 2
    
3.
Nakamura T, Ogata H, Katsuyama T. Pigmented dermatofibrosarcoma protuberans. Report of two cases as a variant of dermatofibrosarcoma protuberans with partial neural differentiation. Am J Dermatopathol 1987;9:18-25.  Back to cited text no. 3
    
4.
Ding JA, Hashimoto H, Sugimoto T, Tsuneyoshi M, Enjoji M. Bednar tumor (Pigmented dermatofibrosarcoma protuberans). An analysis of six cases. Acta Pathol Jpn 1990;40:744-54.  Back to cited text no. 4
    
5.
Marcus JR, Few JW, Senger C, Reynolds M. Dermatofibrosarcoma protuberans and the Bednar tumor: Treatment in the pediatric population. J Pediatr Surg 1998;33:1811-4.  Back to cited text no. 5
    
6.
Kobayashi T, Hasegawa Y, Konohana A, Nakamura N. A case of Bednar tumor: Immunohistochemical positivity for CD34. Dermatology 1997;195:57-9.  Back to cited text no. 6
    


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