511 Pleomorphic dermal sarcoma (PDS): Patterns of upstaging, recurrence, and adjuvant treatment following mohs micrographic surgery (MMS)

PDS is an aggressive cutaneous malignancy that often misdiagnosed as atypical fibroxanthoma(AFX), a low-grade spindle cell tumor, on partial biopsies. Misdiagnosis may lead to falsely optimistic prognosis and incomplete management plans. This study describes the largest published cohort of head neck treated with MMS rates upstaging, adjuvant treatment use, recurrence. case series identified cases from prospectively managed database at academic center between July 2005-2022. Patients were called medical records reviewed assess following outcomes: rate upstaging preoperative diagnosis AFX/uncertain tumor postoperative PDS; modalities; recurrence/metastasis; disease-specific death. Of 38 tumors, 26% previously treated. 89% upstaged PDS. 95% obtained clear margins 5% required additional resection for calvarium invasion. Postoperative lymph node assessment was performed in 10/38 patients, though none resulted positively. Adjuvant radiation chemotherapy arranged 4/38 1/38 respectively. Local recurrence 5%, both progressed metastatic disease. Metastatic 16% (6/38) [in-transit, n=1; nodal, n=3; distant, n=2]. Average time disease progression 9.9 months (range 3.9-18.5). No deaths occurred during mean follow-up 20.8 0-93.3). diagnosed only after definitive MMS. Mohs surgeons should be aware risk when biopsy shows AFX/spindle tumor. While enables local control PDS, surveillance regional distant metastases imperative. Additional research needed effect long-term outcomes.