Many of the symptoms of different types of histiocytosis are common physical problems that are not specific to these diseases. This makes histiocytosis difficult to diagnose. These symptoms include pain, fever, rash, and frequent urination.

• Sinuses and eyes: Tumors located in and around the sinuses can cause discomfort behind the face. Those around or behind the eyes can lead to visual problems or cause the eyes to bulge.
   
• Skin: Histiocytosis in the skin can cause rashes and inflammation. This may be painful or itchy. In some cases, it is disfiguring.
   
• Brain: Histiocytosis in the brain may cause a variety of symptoms. These include trouble with balance, hormonal imbalances, headaches, issues with strength or sensation, and difficulties with thinking and memory.
   
• Bones: Tumors in weight-bearing bones, such as the legs or spine, can cause severe pain. They may also cause the bones to fracture.
   
• Internal organs: Tumors in the kidneys, liver, lymph nodes, or other organs may result in disrupting the function of the organs, swelling (especially in the lymph nodes), and other related symptoms.

Histiocytosis can also cause other more general symptoms. These are due to increased inflammation. When inflammation is present in the body, there are more of the molecules called cytokines. The increase in cytokines can cause people to feel sick. Symptoms of this type of inflammation include fatigue, sweating, and a general feeling of weakness.