Atypical Chest Wall Cystic Hygroma in a Toddler: A Case Report and Comprehensive Review.

Lymphangiomas, also known as cystic hygromas, are rare benign lymphatic malformations that typically occur in the head and neck region. Breast or chest wall involvement in pediatric patients is exceptionally rare, with only a few cases reported in the literature. We report a case of a three-year-old boy who presented with a progressively enlarging right breast mass. Unsupervised topical creams and massage led to further enlargement. Laboratory investigations showed mild elevation in prolactin levels, which normalized after surgery. Ultrasonography demonstrated multiple cystic lesions, the largest of which was oval and measured 26 mm in diameter, along with an enlarged right axillary lymph node. Computed tomography (CT) scan showed a well-defined oval mass (51 × 26 mm) in the right chest wall. The patient underwent surgical excision, and a complete histopathological examination was performed. Histopathological examination revealed multiple lymphatic spaces lined by flattened endothelial cells forming a tumorous mass, with both cavernous and capillary-type lumens. The diagnosis of lymphangioma was confirmed. No mammary tissue was detected, and cancer was excluded. Subsequent evaluations over one week indicated full recovery with normalized prolactin levels. This case underscores the necessity of including lymphangioma in the differential diagnosis of young chest wall tumors. Although this condition is uncommon, early detection and appropriate surgical intervention result in favorable outcomes with a low chance of recurrence.