P022 Dermatofibrosarcoma protuberans of the pubic region: two unusual cases

Abstract

Dermatofibrosarcoma protuberans (DFSP) is an indolent dermal tumour most commonly affecting the trunk and limbs. Fewer than 70 cases of vulval or pubic DFSP have been reported in the literature. We present two cases of pubic DFSP managed at a tertiary referral centre. Case 1. A 36-year-old woman presented with a 16-year history of an asymptomatic pubic mass showing a recent change in colour and growth. Examination revealed a superficial, mobile lesion on the mons pubis. Punch biopsy demonstrated CD34+ spindle cells in a storiform pattern, and computed tomography showed no distant spread. Stage 1 slow Mohs histology revealed fibrosarcomatous transformation with a herringbone pattern, reduced CD34 expression, COL1A1:PDGFB fusion mutation and increased Ki-67 index. Stage 2 excision achieved clear margins. Case 2. A 41-year-old woman presented with a long-standing, asymptomatic mass involving the pubis and right labia majora. Examination showed a lobulated, superficial lesion near the anterior fourchette of the vagina. Punch biopsies revealed CD34+ spindle cells negative for S100, SOX10, smooth muscle actin, p40, MART-1 and CD68. Magnetic resonance imaging demonstrated no metastasis. She underwent Mohs surgery followed by slow Mohs in conjunction with plastic surgery, achieving clear margins. These cases demonstrate the diagnostic and management challenges of DFSP in the pubic region. Diagnostic uncertainty arose from the rarity of the disease and the resemblance to benign lesions. One case exhibited high-risk fibrosarcomatous transformation. Despite multidisciplinary input, referral pathways were unclear, reflecting limited awareness. Surgical management also carried psychosocial and sexual implications. Pubic DFSP may mimic benign lesions, delaying diagnosis. These cases emphasize the importance of clinicopathological correlation in rare or atypical tumours to ensure accurate diagnosis and appropriate specialist referral. Multidisciplinary management is essential to optimize oncological and functional outcomes.