Unusual recurrence in ureters and maxillary sinus of Langerhans cell histiocytosis involving mastoid bone

We present a case of Langerhans cell histiocytosis (LCH) diagnosed in the mastoid bone. The tumor recurred in the ureter and maxillary sinus mucosa two years later. The diagnosis of LCH was based on morphology and immunohistochemistry. Involvement of the ureter and the maxillary sinus in LCH is extremely rare. To the best of our knowledge, this is the first case of LCH affecting the mastoid bone in a 16-year-old boy and recurring later in the ureter and maxillary sinus mucosa.