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CASE REPORT
Ahead of print publication  

Pigmented dermatofibrosarcoma protuberans: A case report and review of literature


 Department of Radiation Oncology, VMMC and Safdarjung Hospital, New Delhi, India

Date of Submission27-May-2022
Date of Acceptance03-Aug-2022
Date of Web Publication01-Nov-2022

Correspondence Address:
Aashita ,
Department of Radiation Oncology, VMMC and Safdarjung Hospital, New Delhi
India
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jrcr.jrcr_33_22

  Abstract 

Dermatofibrosarcoma protuberans (DFSP) is a rare cutaneous sarcoma. Bednar tumor (BT) or pigmented DFSP is a rarely reported variant of it. The only differentiating feature between them is the presence of melanocytes on histopathological examination. We report a case of a 23-year-old female who presented with a recurrent lump in the right thigh that on histopathological evaluation was diagnosed as BT. Less than hundred cases of BT have been recorded to date, with only five cases originating from the thigh. Clinicopathological features of recurrent cases have been compared as local recurrence is less commonly reported.

Keywords: Bednar tumor, cutaneous sarcoma, pigmented dermatofibrosarcoma protuberans, recurrence, thigh



How to cite this URL:
Aashita, Sharma R, Yadav V, Kapoor A, Singh N. Pigmented dermatofibrosarcoma protuberans: A case report and review of literature. J Radiat Cancer Res [Epub ahead of print] [cited 2022 Dec 4]. Available from: https://www.journalrcr.org/preprintarticle.asp?id=360284


  Introduction Top


Dermatofibrosarcoma protuberans (DFSP) is a rare sarcoma of the dermis and subcutaneous tissue. It constitutes <0.1% of all malignancies. Pigmented DFSP (PDFSP) or Bednar tumor (BT) is a very rare variant of DFSP and comprises only 1%–5% of all cases.[1] The tumor is of intermediate grade showing an infiltrative growth pattern, with a higher propensity for local recurrence than metastasis.[2] Recurrence has been reported in 13% of cases of BT, with an average recurrence-free interval of 8 years.[3]


  Case Report Top


A 23-year-old female presented with a gradually progressive lump in the medial aspect of the right thigh for 8 months that was recently associated with intermittent pain. She had undergone local excision of a similar lump at the same site 11 months ago at a local hospital that recurred within 3 months and progressed to the current size. No reports of the same were available with the patient. There was no history of trauma. It was a 4 cm × 4 cm firm round mass that was fixed to the underlying muscle. It was not associated with any discharge, bleeding, tenderness, local rise of temperature, or numbness in the right lower limb.

On magnetic resonance imaging, there was a well-defined, encapsulated, lobulated soft tissue lesion of size 4 cm × 3 cm × 4.2 cm in the subcutaneous plane in the medial aspect of the right thigh, 10.8 cm above the joint line [Figure 1]. Fine-needle aspiration cytology revealed a mesenchymal lesion suggestive of a soft tissue sarcoma, for which wide local excision (WLE) was done.
Figure 1: Magnetic resonance imaging of the right thigh showing well-defined encapsulated lobulated lesion in subcutaneous plane in the medial aspect of the right lower thigh of size 4 cm × 3 cm × 4.2 cm. (a) Coronal T1 image, (b) coronal T2 image, (c) axial T2 image

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On gross examination, a tumor of size 4 cm × 3.5 cm × 3 cm was seen arising from the subcutaneous tissue pushing the skin from below and stretching it out over the mass. Cut sections showed spindle cell tumor in the subcutaneous tissue with thinned out epidermis. Cells were arranged in a whorled pattern interspersed with pigment-laden cells, giant cells, and cyst macrophages [Figure 2]. Spindle cells were positive for vimentin, while melanin-containing cells were positive for melan-A. Margins were free of tumor with a deep resected margin of 0.1 cm. She was diagnosed with a case of pigmented dermatofibrosarcoma and planned for adjuvant radiation due to recurrence, close margin, and young age.
Figure 2: Histopathological examination of pigmented dermatofibrosarcoma protuberans. (a) Under low power, elongated, dense spindle-shaped cells arranged in storiform pattern characteristic of dermatofibrosarcoma. (b) Under high power, many pigment-laden cells (both singly and in small clusters) were seen with a few giant cells interspersed between the tumor

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  Discussion Top


The incidence of PDFSP is low. Although the most common age group is 20–50 years, PDFSP has been reported in neonates as well as geriatric population.[4] There is no gender predisposition as it occurs equally in males and females. The most common site involved is the trunk followed by the shoulder.[5]

PDFSP is a locally aggressive tumor and recurs frequently if inadequate surgical margins are obtained, however, very few metastatic cases have been reported till now.[3] Chances of metastasis increase in a case with multiple recurrences and are more common through hematological route whereas lymphatic spread remains rare.[6] The exact pathogenesis is still unknown, but 90% of cases have translocation fusion gene of collagen type 1 alpha 1 (COL1A1) and platelet-derived growth factor-beta (PDGFB).[4]

Patients usually are asymptomatic or can present with a lump or skin changes. Pain can be present depending on the site of the tumor and structures involved. It occurs as a firm nodular mass that becomes lobulated as it enlarges. It is fixed to overlying skin resulting in an appearance of a plaque, scar, or umbilicated area. Usually, it is mobile over underlying structures unless it is infiltrating it. Grossly, the color of the tumor can vary from flesh-colored to brown depending on the number of pigmented cells.[3] Histologically, spindle-shaped cells are arranged tightly in storiform or cartwheel patterns with infiltration of subcutaneous tissue in chicken-wire or honeycomb pattern similar to that seen in our case. The spindle cells are positive for vimentin and CD34, while melanin-containing cells are positive for S-100.[4]

Comparison of BT with conventional DFSP is mentioned in [Table 1]. The only clinicopathological difference between PDFSP and conventional DFSP is the presence of dendritic melanocytes within tumor and corresponding immunohistochemical (IHC) markers.[7] [Table 1]
Table 1: Comparison between Bednar tumor and conventional dermatofibrosarcoma protuberans[1],[2],[3]

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The important differential diagnoses are dermatofibroma, DFSP, pigmented neurofibroma, neurocristic cutaneous hamartoma, psammomatous melanotic schwannoma, and desmoplastic malignant melanoma, which are confirmed by IHC.[2]

Although the definitive treatment is excision, due to the rarity of the disease, no guidelines have been formulated yet. In few cases reported, the treatment strategy usually was WLE with a margin of 2.5–3 cm. In cases, where the tumor site was such that wide margins could not be achieved, the patient was treated with external beam radiation.[3],[8] Use of imatinib, a tyrosine kinase inhibitor, has been tried in DFSP with some effects in decreasing tumor size to make it amenable for excision, but it was effective only in tumors with COL1A1/PDGFB fusion gene.[8],[9] It is difficult to predict recurrence. As, in our case, deep resected margin was 0.1 cm, the patient has been planned for adjuvant radiation.

Since the first description of this tumor by Bednar in 1956, less than 100 cases of BT have been recorded in the literature only. Five of them were reported in the thigh [Supplementary Table 1].[5],[7],[10][Additional file 1] Ten cases of BT had recurrence ever whose clinical features are summarized in [Table 2] along with the present case.
Table 2: Comparison of recurrent cases of primary Bednar tumor as reported in the literature

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  Conclusion Top


Considering the infrequent incidence of PDFSP, the possibility of Bednar tumor should be kept in mind while differentiating from other cutaneous tumors for earlier diagnosis and adequate management of the patient. The recurrence rate documented in the literature may not be what is actually seen as there is no study where long-term follow-up has been done in BT cases. A close follow-up is needed after the completion of treatment for early detection of local recurrence and metastasis.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



[17]

 
  References Top

1.
Llombart B, Serra-Guillén C, Monteagudo C, López Guerrero JA, Sanmartín O. Dermatofibrosarcoma protuberans: A comprehensive review and update on diagnosis and management. Semin Diagn Pathol 2013;30:13-28.  Back to cited text no. 1
    
2.
Reis-Filho JS, Milanezi F, Ferro J, Schmitt FC. Pediatric pigmented dermatofibrosarcoma protuberans (Bednár tumor): Case report and review of the literature with emphasis on the differential diagnosis. Pathol Res Pract 2002;198:621-6.  Back to cited text no. 2
    
3.
Porter C, Vincetic A, Saleh ME, Goldstein H. Pigmented dermatofibrosarcoma protuberans of the foot with fibrosarcomatous changes: A review and case presentation. J Foot Ankle Surg 2002;41:186-91.  Back to cited text no. 3
    
4.
Zhang Y, Chen H, Sun J. Two childhood cases of pigmented dermatofibrosarcoma protuberans with atrophic change. Eur J Dermatol 2018;28:225-6.  Back to cited text no. 4
    
5.
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. 5
    
6.
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. 6
    
7.
Fletcher CD, Theaker JM, Flanagan A, Krausz T. Pigmented dermatofibrosarcoma protuberans (Bednar tumour): Melanocytic colonization or neuroectodermal differentiation? A clinicopathological and immunohistochemical study. Histopathology 1988;13:631-43.  Back to cited text no. 7
    
8.
Hidaka T, Fujimura T, Hashimoto A, Aiba S. Successful treatment of pigmented dermatofibrosarcoma protuberance on the nasal root with cyberknife radiosurgery. Acta Derm Venereol 2012;92:658-9.  Back to cited text no. 8
    
9.
McGee MW, Boukhar SA, Monga V, Weigel R, Phadke SD. Dermatofibrosarcoma protuberans – The use of neoadjuvant imatinib for treatment of an uncommon breast malignancy: A case report. J Med Case Rep 2019;13:374.  Back to cited text no. 9
    
10.
Mentzel T, Beham A, Katenkamp D, Dei Tos AP, Fletcher CD. Fibrosarcomatous (“high-grade”) dermatofibrosarcoma protuberans: Clinicopathologic and immunohistochemical study of a series of 41 cases with emphasis on prognostic significance. Am J Surg Pathol 1998;22:576-87.  Back to cited text no. 10
    
11.
Kini H, Raghuveer CV, Pai MR, Kalpana S. Fibrosarcomatous Bednar tumor with distant metastases – A case report. Indian J Pathol Microbiol 2004;47:26-9.  Back to cited text no. 11
    
12.
Akasaka T, Ohyama N, Kon S. A case of pigmented dermatofibrosarcoma protuberans (Bednar tumor). J Dermatol 1997;24:390-4.  Back to cited text no. 12
    
13.
Santa Cruz DJ, Yates AJ. Pigmented storiform neurofibroma. J Cutan Pathol 1977;4:9-13.  Back to cited text no. 13
    
14.
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. 14
    
15.
Mochizuki Y, Narisawa Y, Kohda H. A case of Bednar tumor recurring after 23 years. J Dermatol 1996;23:614-8.  Back to cited text no. 15
    
16.
Nagahori H, Makino T, Toyoda M, Matsui C, Kagoura M, Morohashi M. Bednar tumor (Pigmented dermatofibrosarcoma protuberans). Skin Cancer 1997;12:397-401.  Back to cited text no. 16
    
17.
Onoda N, Tsutsumi Y, Kakudo K, Ozawa A, Niizuma K, Ohkido M, et al. Pigmented dermatofibrosarcoma protuberans (Bednár tumor). An autopsy case with systemic metastasis. Acta Pathol Jpn 1990;40:935-40.  Back to cited text no. 17
    


    Figures

  [Figure 1], [Figure 2]
 
 
    Tables

  [Table 1], [Table 2]



 

 
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