Dermatofibrosarcoma protuberans of the vulva: a case report
- 1Agrı Kadin Dogum ve Cocuk Hastanesi, Agri, Turkey
- 2Department of Obstetrics and Gynecology, Medical University of Graz, Austria
- 3Department of Pathology, Medical University of Graz, Austria
- Published 5 March 2009
Dermatofibrosarcoma protuberans (DFSP) is a low-grade to intermediate-grade well-differentiated sarcoma of dermal origin. Local recurrence rates are high but distant metastases are rare. This report describes a case of vulvar DFSP requiring four resections for primary clearance. A 56-year-old woman referred after excision of a vulvar tumour and histology had DFSP extending to the resection margins. Two more extended excisions again yielded a specimen with positive margins. The last excision was performed with intraoperative frozen section analysis of the margins. Frozen section analysis of the resected specimen revealed clear margins and this was confirmed by final pathology. The postoperative course was uneventful. The patient has been without recurrence for 15 months. A wide and deep local excision is recommended for both primary and recurrent lesions. The patient had three resections before clear surgical margins were achieved. Intraoperative frozen section analysis is helpful in assessing resection margins.
Primary sarcomas and mesenchymal tumours of intermediate malignancy of the vulva are rare, accounting for about 1.5–5% of all malignant vulvar neoplasms.1 Dermatofibrosarcoma protuberans (DFSP) is a low-grade to intermediate-grade well-differentiated sarcoma of dermal origin. Local recurrence rates are high but distant metastases are rare.2,3 Most DFSPs are found on head and neck, upper extremity, trunk and lower extremity.4 Vulva is an unusual site for this tumour with less than 30 cases reported in English literature.2,3,5–8 We report a case of vulvar DFSP requiring four resections for primary clearance.
A 56-year-old woman was referred from another institution after incomplete excision of a vulvar tumour which was performed in conjunction with elective panniculectomy. Histological examination of the initial excisions revealed a DFSP extending to the resection margins. The patient gave a history of a subcutaneous nodule about 3 cm diameter which had grown over a period of approximately 18 months. At our institution, physical examination showed well healed scars after the previous procedures but no gross neoplasia. No inguinal lymph nodes were palpable. Wide and deep local excision of the previous scar was performed, although no neoplastic tissue was recognisable macroscopically. Surprisingly, histological examination again showed residual DFSP extending to the cranial cutaneous resection margins of the specimen (fig 1).
Four days later the last excision performed with intraoperative frozen section analysis of the margins by a dermato/gynaecopathologist (SR). Frozen section analysis of the entire circumference of the resected specimen with a total of 12 tangential sections indicated clear margins and this was confirmed by final pathology. The closest lateral surgical resection margin was 1.2 cm from the DFSP and basal resection margin was in excess of 2 cm.
OUTCOME AND FOLLOW-UP
Postoperative course was uneventful and the patient has been followed without recurrence for 15 months.
Most cases of vulvar DFSPs have been described as solitary subcutaneous nodules as in our patient, but they may present as multinodular masses or plaque-like lesions of the skin with surrounding red to blue discoloration. DFSP can be asymptomatic, but pain, ulceration or bleeding may be associated with vulvar DFSP.2,7
Histologically, DFSP is characterised by densely cellular intradermal growth with spindle cells arranged in a storiform pattern and an infiltrative growth pattern at the base of the tumour. Differential diagnosis between DFSP and fibrous histiocytoma can be difficult if a biopsy specimen contains only the superficial portion of the lesion. Tumour cells of a DFSP show little cytological atypia, if any, and have typically fewer than 5 mitotic figures per 10 high-power fields. Giant cells are also absent. Infiltrative growth pattern along the septae of the subcutaneous fat and strong and diffuse staining with antibody to CD34 in DFSP are helpful in distinguishing a DFSP from other benign spindle-cell tumors,1,4 since benign fibrous histiocytomas are negative for CD34 and positive for factor XIIIa. In our case, mitotic rate was 2/10 high-power fields and immunohistochemical staining revealed a strong staining with antibody to CD34 and negative staining with antibody to factor XIIIa.
A wide and deep local excision is recommended for both primary and recurrent lesions of DFSP1–10 since microscopic projections of tumour often extend far beyond the macroscopically recognisable tumour. Our patient had three resections before clear surgical margins were achieved. As documented in the present case, intraoperative frozen section analysis may be helpful in assessing resection margins. When incompletely or marginally excised, DFSP shows a locally aggressive behaviour. Reported recurrence rates are between 20% and 49%.6,7 There is a trend toward decreasing recurrence rates with increasing clear margins of resection. Mohs micrographic surgery provides microscopic evaluation of tumour margins to ensure complete excision of DFSP at high risk of recurrence.9 If the resection margin is greater than 3 cm, the recurrence rate is 20% compared with 41% if the margin is 2 cm or less.10 Surgery seems to be effective to primary and recurrent lesions. Combined conservative resection and postoperative radiation have been indicated when inadequate excision is performed which would compromise cosmetic and functional results.5 Distant metastases of DFSP (lung, bone) occur in less than 6% of cases and they are frequently associated with a history of multiple local recurrences.6,8 As most recurrences occur within the first 3 years of surgery, DFSP requires careful follow-up for local and distant recurrence.5
A frozen section is helpful to evaluate resection margins of the definitive resection intraoperatively, and patients with dermatofibrosarcoma protuberans require long-term follow-up for local and distant recurrence.
Competing interests: none.
Patient consent: Patient/guardian consent was obtained for publication.