Uncommon Presentation of Hidrocystoma in a 14-Year-Old Girl.

Hidrocystoma is a rare benign cystic tumor of sweat gland origin, most commonly located in the periorbital region, with uncommon occurrence in the retroauricular area. This article presents a case of a 14-year-old patient with a retroauricular mass present for approximately four years, which had remained stable in size until a gradual enlargement was observed over the preceding 11 months. The lesion was associated with intermittent fluid discharge and periodic episodes of local skin inflammation, likely related to mechanical irritation from earrings worn by the patient. Otherwise, the lesion was asymptomatic, with no persistent pain or systemic signs of infection. Clinical examination revealed a well-circumscribed, cystic lesion located in the retroauricular region. Ultrasonographic evaluation demonstrated features consistent with a benign cystic structure. Based on clinical and imaging findings, the lesion was qualified for surgical excision. Complete removal of the mass was performed without complications. Histopathological examination confirmed the diagnosis of hidrocystoma. The postoperative course was uneventful, with no recurrence observed during follow-up. This case highlights a rare location and atypical clinical course of hidrocystoma in an adolescent patient, emphasizing the role of clinical assessment and ultrasonography in preoperative evaluation, as well as the potential impact of chronic mechanical irritation on local inflammatory episodes. Surgical excision remains an effective definitive treatment.