Verrucous carcinoma arising from chronic sacrococcygeal pilonidal disease: a case report.

INTRODUCTION AND IMPORTANCE: Pilonidal sinus disease is a common benign disorder of the sacrococcygeal region characterized by chronic inflammation, recurrent infection, and sinus tract formation. Although generally nonneoplastic, long-standing and chronically inflamed pilonidal sinuses carry a small risk of malignant transformation. Verrucous carcinoma, a rare well-differentiated variant of squamous cell carcinoma (SCC), is exceptionally uncommon in this setting, highlighting the importance of routine histopathological examination of excised specimens for accurate diagnosis and appropriate management. CASE PRESENTATION: A 63-year-old man presented with a 5-year history of chronic pilonidal disease associated with recurrent inflammation, purulent discharge, and delayed wound healing. Physical examination revealed a 5 × 5 cm inflamed lesion in the sacrococcygeal region. The patient underwent wide local excision with reconstruction using a Limberg flap. Histopathological examination confirmed well-differentiated verrucous carcinoma without lymphovascular invasion, and the surgical margins were free of tumor, with a clear margin of 5 mm. No recurrence was observed during 12 months of follow-up. CLINICAL DISCUSSION: Malignant transformation in pilonidal sinus disease is rare, occurring in approximately 0.1% of chronic cases, with SCC being the most frequently observed malignancy. Verrucous carcinoma represents an uncommon subtype with locally aggressive behavior but low metastatic potential. Chronic inflammation and recurrent infection are believed to contribute to neoplastic transformation through repeated tissue injury and oxidative stress. In cases of delayed healing, rapid lesion growth, or atypical wound characteristics, the possibility of malignancy should be considered. CONCLUSION: Verrucous carcinoma arising from chronic pilonidal sinus disease is an exceptional yet clinically significant entity. Clinicians should maintain vigilance for malignancy in recurrent or poorly healing pilonidal disease.