Rare case of pilonidal sinus of scalp: a case report.

Background: Pilonidal sinus is a chronic inflammatory condition that typically occurs in the sacrococcygeal region and rarely in other locations. Scalp pilonidal sinus is extremely uncommon, making this case noteworthy as it expands the differential diagnosis for scalp nodular lesions.

Case presentation: A 16-year-old girl presented with a persistent fluid-draining nodule on the top of her head, present for over a decade. She had a history of scalp injury at birth. Examination revealed a 1×2 cm mobile, tough nodule with a central opening and sparse surrounding hair. Imaging showed a gas density under the scalp but no bone involvement. The nodule was surgically excised. Histopathology confirmed pilonidal sinus, showing embedded hair, sebaceous gland involvement, and inflammatory cell infiltration. The patient recovered fully, with no recurrence or complications during three years of follow-up.

Conclusions: This rare case of pilonidal sinus on the scalp highlights the importance of considering it in the differential diagnosis of scalp nodular lesions, particularly in patients with a history of trauma. It emphasizes the need for surgical treatment and careful follow-up to prevent recurrence.