|Ahead of print publication
Pigmented dermatofibrosarcoma protuberans: A case report and review of literature
Aashita, Rajiv Sharma, Vikas Yadav, Anuja Kapoor, Nisha Singh
Department of Radiation Oncology, VMMC and Safdarjung Hospital, New Delhi, India
|Date of Submission||27-May-2022|
|Date of Acceptance||03-Aug-2022|
|Date of Web Publication||01-Nov-2022|
Department of Radiation Oncology, VMMC and Safdarjung Hospital, New Delhi
Source of Support: None, Conflict of Interest: None
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|| |
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. The tumor is of intermediate grade showing an infiltrative growth pattern, with a higher propensity for local recurrence than metastasis. Recurrence has been reported in 13% of cases of BT, with an average recurrence-free interval of 8 years.
| Case Report|| |
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|| |
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. 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.
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. Chances of metastasis increase in a case with multiple recurrences and are more common through hematological route whereas lymphatic spread remains rare. 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).
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. 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.
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. [Table 1]
|Table 1: Comparison between Bednar tumor and conventional dermatofibrosarcoma protuberans,,|
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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.
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., 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., 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].,,[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|| |
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
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2]