Hard bumps beneath the skin, especially when they appear on the face, can be embarrassing and difficult to conceal. There are a variety of causes responsible for the formation of these bumps. Some of these causes can even be dangerous if left untreated.

Sunlight helps your body produce vitamin D and it regulates your circadian rhythm, or body clock. Certain health conditions, however, can leave you with unpleasant reactions after you go out in the sun.

Egyptians believed the healing powers of gold could cure all manner of physical, mental and spiritual ailments. Romans used gold preparations for treatment of skin lesions and sores. It is believed that Cleopatra wore pure gold for a radiant complexion. In ancient Chinese medicine, gold was the secret to youthful skin.

Eczema is a type of skin condition or dermatitis that affects many people in the United States. Eczema of the scalp is diagnosed as seborrheic dermatitis and presents with common signs and symptoms of redness, itchiness, flaky dandruff, irritation and scaly, dry patches.

A cyst is a sac that can be filed with air, fluid or tissue. They can appear anywhere on the body. Scalp cysts can range in size and shape and are typically benign.

The scalp is a common site of rashes for a number of reasons. It is exposed to the environment, and so it can be irritated by toxins. The skin on the scalp is also thin and has numerous sweat and oil glands under it, making it sensitive to irritation and rashes.

An allergic reaction that causes bumps on the skin is often from allergic contact dermatitis. Direct contact with an allergen causes the area to become inflamed. A systemic allergic reaction can also cause hives on the skin. Consult with your doctor for a proper diagnosis and treatment of the bumps on your skin.

The tiny white bumps or small cysts that form on your skin are called milia, reports the National Institutes of Health's MedlinePlus resource. They are frequently seen in newborn babies, but they can occur at any age and for many different reasons.

You’re probably very aware of any unfamiliar bumps on your scalp — after all, you’re performing a self-examination every time you shampoo your hair. If you feel a strange bump or growth on your scalp, it’s a good idea to see your doctor.

Keratosis is a disease characterized by an overgrowth of horny tissue or tissue containing a protein called keratin. There are several different types of keratosis with varying degrees of severity including actinic keratosis, keratosis pilaris, hyperkeratosis, seborrheic keratosis and keratosis follicularis.

You may experience bumps on your skin late in pregnancy or after giving birth, according to BabyCenter. There could be many causes for itchy bumps on your abdomen during or after pregnancy, but the good news is that the bumps are typically not a sign of anything serious and they tend to go away quickly after delivery.

Acne can be an unsightly skin condition that usually attacks the face, making the condition highly visible. It causes a variety of skin lesions that look like red bumps and often have black or white tips, and which may develop a crust.