Anterior Chest Wall Pilonidal Sinus Mimicking Recurrent Abscess: Diagnostic Pitfalls and Therapeutic Implications.

Pilonidal sinus is a chronic inflammatory skin condition predominantly found in the sacrococcygeal region, characterized by recurrent infections and sinus tract formation. Occurrences outside this area, particularly on the anterior chest wall, are exceedingly rare and prone to misdiagnosis. We report a rare case of a 24-year-old Chinese man presenting with a 3-year history of a recurrent, draining lesion on the anterior chest wall. Initial treatment via simple incision and drainage for a presumed sebaceous cyst resulted in delayed wound healing and persistent purulent discharge. Subsequent magnetic resonance imaging (MRI) and computed tomography (CT) revealed a localized superficial lesion. Definitive surgical debridement uncovered a sinus tract containing embedded hair fragments. Histopathological examination confirmed a pilonidal sinus with a robust foreign body giant cell reaction and chronic inflammation. After complete resection, during the nearly two-year follow-up period, the healing has been smooth, and no recurrence has been observed. This case highlights the necessity of detailed clinical history-taking and the inclusion of ectopic pilonidal sinus in the differential diagnosis of refractory chest wall abscesses to prevent repeated, ineffective interventions.