Final answer:
Langerhans histiocytosis (LCH) commonly affects the bones, with the skull, long bones, and spine being the most common sites of bony lesions.
Step-by-step explanation:
Langerhans histiocytosis (LCH) is a rare condition that affects the immune system and causes the accumulation of Langerhans cells in different organs, including bones. In LCH, the most common sites of bony lesions are the skull, long bones (such as the femur or tibia), and the spine. These lesions can cause pain, swelling, and abnormal bone growth.
For example, in a study published in the journal Pediatric Blood & Cancer, researchers found that among 621 patients with LCH, 71% had bone involvement, and the most common sites were the skull (43%), long bones (36%), and spine (24%).
It's important to note that the exact distribution of bony lesions can vary from person to person, and other sites like the pelvis or ribs can also be affected, although less frequently.