Dr. Nirenberg Publishes Article: Is that blister really a blister?

May 3, 2008


Published in the Fixing Your Feet Ezine – http://vonhof.typepad.com/fixingyourfeet/
By Michael Nirenberg, DPM

Having treated thousands of feet, I often see patients complaining of a blister that is actually a type of cyst called a mucoid cyst. Recognizing you have a mucoid cyst and not a blister is important because Img_4370mucoid cysts are treated differently. The key differences between blisters and mucoid cysts are:

•    Blisters can occur anywhere on the foot. Common places for blisters are the ball of the foot, the back of the heel, or on or between the toes. Mucoid cysts only occur on the top of the toes or fingers beside the nail or about a centimeter from the nail.
•    Blisters often develop from friction. We don’t know why mucoid cysts develop, however, scientists believe they are the result of minor trauma to the toe or finger. In runners, this could be due to the repetitive jamming of the toe against the shoe. 
•    Blisters contain a clear watery-like fluid sometimes tinged with blood, whereas mucoid cysts have a thick, jelly-like substance.
•    Blisters come in various shapes and sizes; mucoid cysts are dome shaped and round.

There are two types of mucoid cysts: those connected to a joint inside the finger or toe and those that Img_4372are isolated or not connected to a joint. Most mucoid cysts are painless, though tight-fitting shoes can cause them to become painful. 
     Mucoid cysts tend to occur more often in females and usually during the fifth to seventh decades of life, but I have seen them occur in people of all ages, including teenagers.

The treatment for a blister is usually to drain it. Mucoid cysts will usually recur if simply drained; they require surgery. The doctor will need to excise the entire cyst, often dissecting down to the bone. However, if the mucoid cyst is not painful, you can ignore it or if it only causes minimal discomfort, your doctor may recommend padding it with moleskin or felt.
     Whenever any mass or lesion occurs on your foot, have it checked by a podiatrist; for lesions or masses elsewhere on your body, see a dermatologist. Even though you may believe it’s nothing serious, in some cases, an abnormal lesion or mass could be cancer.

Dr. Michael Nirenberg, “America’s PodiatristSM,” is a podiatric physician, surgeon and forensic podiatrist. 

Photos are used with permission: Dockery GL: Cutaneous Disorders of the Lower Extremity, WB Saunders, 1997.


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