[501] Clinical Outcomes for a Large Cohort of Patients with Dermatofibrosarcoma Protuberans with Fibrosarcomatous Transformation.

Michael S McLemore, Alexander J Lazar, Wei-Lien Wang. The University of Texas M.D. Anderson Cancer Center, Houston

Background: Dermatofibrosarcoma protuberans (DFSP) is a locally aggressive cutaneous sarcoma characterized by storiform spindle cells. In some tumors, fibrosarcomatous transformation (DFSP-FS) occurs, typically with a sharply demarcated cellular area in a fascicular growth pattern. Several studies have shown DFSP-FS to variably increase risk of local recurrence and distant metastasis. We examined the clinical outcome in a large cohort of patients with DFSP-FS treated at a single institution.
Design: The pathology files were examined from 1985-2010 for patient cases with DFSP showing FS transformation. Clinical data and outcomes were tabulated.
Results: From 1985-2010, 776 patients with DFSP were identified with 9% (n=71) having FS transformation. The mean age of these DFSP-FS patients was 46 years (range: 18-79) with a male predominance (1.6:1). Ethnicity was known in 54 cases: Caucasian, 57%; Hispanic, 22%; Black, 15%; and Asian, 6% – percentages similar to our overall patient population. Common anatomic sites (n=71) included back (31%), head and neck (15%), abdomen (13%), chest (10%), upper extremity (10%), and groin (8%). The mean tumor size was 7.8 cm (range: 1.0-30.0). Where available (n=42), the median follow-up was 42 months (range: 1-377). Overall metastatic frequency was 21% (9/42); the median time to metastasis was 28 months (range: 18-361). The most common metastatic site was lung (78%, 7/9). Local recurrence was seen in 40% of DFSP-FS patients (17/42), and 41% of these recurrent cases with follow-up (7/17) developed metastatic disease. The median time to recurrence was 21 months (range: 4-309). Margins were microscopically positive in 48% of cases at resection (22/46); of these cases with follow-up, 47% (8/17) developed local recurrence, and 24% (4/17) developed metastatic disease. At last clinical follow-up, 62% of patients (26/42) had no evidence of disease, 21% (9/42) were alive with disease, 10% (4/42) died of disease, 5% (2/42) were alive with unknown disease status, and 2% (1/42) died of unknown cause. No patients with DFSP lacking FS transformation (n=705) were known to develop metastasis.
Conclusions: DFSP with FS transformation is an aggressive tumor with increased risk of local recurrence and metastasis. Only DFSP cases with FS change were found to metastasize in this large cohort, and the lung was the most common metastatic site. Close clinical follow-up for patients with DFSP-FS is warranted.
Category: Dermatopathology

Monday, February 28, 2011 1:15 PM

Platform Session: Section F, Monday Afternoon


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