Solitary Langerhans cell histiocytosis arising from sternum: a case report.

Langerhans cell histiocytosis (LCH) is a rare idiopathic benign disease characterized by proliferation of Langerhans cells, most commonly in the skull. In extremely rare cases, the tumor can occur in the sternum. A 4-year-old girl presented to our institution with a firm, nontender mass in her anterior chest that had indolently enlarged to approximately 2 cm in diameter over the previous several months. Computed tomography, magnetic resonance imaging, and F18-flurodeoxy-glucose positron emission tomography computed tomography were performed for preoperative diagnosis, but the findings were inconclusive. Therefore, we performed surgical excision under general anesthesia, followed by microscopic and immunohistochemical analysis of the excised specimen. The mass was eventually diagnosed as a LCH arising from the sternum. No postoperative oncological treatment was given, and follow-up has continued for 1 year until the time of writing without any tumor recurrence. To our knowledge, only 10 cases of LCH arising from the sternum have been reported in the medical literature. Among them, surgical approaches including curettage and partial sternotomy were performed in only 6 cases. Without exception, all patients experienced excellent clinical outcomes. Therefore, additional clinical experiences are required. No standard treatment of choice for this disease currently exists. In our experience, curettage of the involved soft tissue mass and bone followed by appropriate reconstruction of the defect is considered a good option for the treatment of solitary LCH of the sternum. In addition, LCH should be considered in the differential diagnoses when a sharp delineated osteolytic mass is detected in the sternum.