Have you ever examined the back of your head? Do you even know what the soles of your feet look like?

If not, maybe it's time to take a peek. Each year at this time — as the May sun and longer days beckon us outside — dermatologists remind people to spend a few minutes inside examining their skin for signs of cancer.

Of course, skin cancers, including dangerous melanomas, are closely linked to sun damage. Most arise on easily seen, frequently exposed areas of the skin, such as the face, limbs and trunk.

But melanomas also can show up between the buttocks, on the soles or the palms or between the toes, or in areas that are hard to see, such as the scalp.

So a good self-exam should include those areas, says Springfield, Ill., dermatologist Stephen Stone, president of the American Academy of Dermatology. The organization encourages monthly self-examinations for signs of skin cancer.

"The so-called 'hidden' melanomas tend to be more advanced when we find them," he says, because people are less likely to notice them or recognize their danger.

Patti Good, 45, of Springfield, a medical transcriptionist, wife and mother of three, says that for a year she felt a bump on the back of her head "and never thought anything about it" until a news article on the signs of melanoma "started my heart racing." She called her family doctor at once and within days was having surgeries to remove a large melanoma and 27 lymph nodes. The nodes were cancer-free, and after one year of interferon treatment plus eight years of careful screenings, Good has seen no further cancer signs.

Stone says it's tricky, though possible, to check your own scalp. He suggests using a cool blow dryer or comb to separate areas of hair and having a friend or spouse check the back of the head.

Some rarer hidden melanomas are found: