Lichen nitidus appears as clusters of tiny, glistening bumps (papules). Characteristics of the bumps include the following:

• Size. The bumps range in size from pinpoint to pinhead size.
• Shape. They are flat topped and round.
• Color. Bumps are usually the same color as your skin. They may be slightly pink on people with lighter skin, or lighter than normal skin color on people with darker skin.
• Location. Lichen nitidus bumps commonly occur on the chest, abdomen, arms and genital areas, including the penis. They rarely occur on the palms, soles of the feet or fingernails. Lichen nitidus may clear up at one site on your body but then appear at another.
• Itch. In rare cases, the bumps of lichen nitidus may itch, sometimes intensely. They may appear in a line where there's a scratch, crease or constant pressure on the skin, such as a fold of skin on the abdomen or the crease of skin on the inside of the elbow or wrist.

The cause of lichen nitidus is unknown. The papules that appear are the result of inflammation controlled by white blood cells called T lymphocytes. Normally, these cells work to heal disease or injury, such as a cut on your finger. Doctors and researchers don't know what prompts T lymphocytes to be activated in lichen nitidus.

Lichen nitidus seems to be more likely to develop in children and young adults.

Association with other diseases

Because lichen nitidus is rare, most information about the disorder is known from individual cases or small studies. Links between lichen nitidus and other diseases aren't well-understood, but they may include:

• Lichen planus, an inflammatory condition usually characterized by patches of red or purple, flat-topped, itchy bumps on the skin or lacy white patches on the mucous membranes of the mouth
• Atopic dermatitis (eczema), an inflammatory skin condition usually characterized by dry, itchy rashes on the face, inside the elbow, behind the knees, and on the hands and feet
• Crohn's disease, inflammation of the lining of your digestive tract, which can lead to abdominal pain, severe diarrhea and malnutrition
• Juvenile rheumatoid arthritis, an inflammatory disease that causes persistent joint pain, swelling and stiffness
• Tuberculosis, an infectious disease that most often affects the lungs

Lichen nitidus is a harmless condition that doesn't result in long-term skin problems or medical complications. However, the appearance of lichen nitidus may cause a person to be self-conscious or embarrassed.