Nodular hidradenoma of the chest wall in a 9-year-old girl: A case report

Introduction Nodular hidradenoma is a rare benign adnexal neoplasm that is exceedingly uncommon in the pediatric population. Due to its nonspecific clinical presentation and overlapping histopathologic features with hidradenocarcinoma, diagnosis and management may be challenging. Case Presentation A previously healthy 9-year-old female presented with a 27 mm x 30 mm, mobile, discolored chest wall mass overlying the lower sternum that demonstrated progressive enlargement over several months. Initial ultrasonography revealed a 2.1 x 0.9 x 1.7 cm complex soft tissue mass with internal vascularity. Subsequent MRI demonstrated a 1.9 x 2.8 cm well-circumscribed, T1 isointense, T2 hyperintense, STR intense lesion with enhancing solid components within the subcutaneous tissues overlying the midline anterior chest wall not involving the underlying sternum, and with early arterial enhancement. Given the complex location between the developing breasts, the patient underwent complete surgical excision with negative margins and complex closure in collaboration with Plastic and Reconstructive Surgery. Extensive dermatopathologic evaluation demonstrated a solid-cystic epithelial tumor composed of monomorphous epithelial cells with clear cytoplasm, confirming nodular hidradenoma without atypical malignant features. The patient continues to undergo close clinical surveillance through the Pediatric Surgery clinic and remains without evidence of disease recurrence at 1 year follow-up. Conclusion Nodular hidradenoma should be considered in the differential diagnosis of persistent superficial soft tissue masses in children, including those occurring at uncommon locations such as the chest wall.