Case of the Mistaken Identify in a Finger Tumor
Surgeons from the Plastic and Reconstructive Surgery department at the University of Pittsburgh present the case of a rare chondroma. A chondroma is a benign tumor made up of cartilage cells. They are usually benign but can cause painful swelling. The most common location is in the hands and feet (fingers and toes).

In this report, an older man (in his mid-70s) put off having the finger evaluated. It was on his nondominant hand and had been growing for several years. It only affected the distal phalanx (tip) of the index finger.

At first, the surgeons thought it was malignant, so the patient decided to have it surgically removed. The procedure to remove the tip of the finger along with the joint is called a disarticulation. But it turned out to be a chondroma under the nail and wasn't malignant after all. The presentation was very unusual. Even with X-rays and MRIs, it looked like a malignant tumor.

Part of the confusion was in the location of the tumor. The type of chondroma he had was extraosseous. That means outside of bone (in this case, under the nail bed). It was very close to the bone and didn't look like a classic chondroma. The nail bed was no longer visible, which is usually a sign of malignancy. None of the X-ray findings were typical for an extraosseous chondroma. An accurate diagnosis wasn't made until it was removed and examined under a microscope.

There are three types of extraosseous chondromas: 1) intra-articular/para-articular, 2) juxtacortical, and 3) chondromas of the soft parts. As the names suggest, these are grouped by location. Intra- or para-articular refers to in or around the joint. Juxtacortical means next to the bone. And of course, chondromas of the soft parts occur in the soft tissues of the fingers or toes.

The authors provide a detailed description of the histology of each type of extraosseous chondroma. Histology refers to the microscopic analysis of the tissue by the pathologist. They advised surgeons to be familiar with these three types of chondromas in order to avoid surgically removing benign lesions (such as occurred in this case).

The patient wasn't disturbed by losing the distal joint when, in fact, disarticulation wasn't necessary after all. He wasn't interested in a complete reconstruction of the finger. So only the minimal amount of surgery was done. Usually, a chondroma is removed with clear margins to prevent local recurrence. Clear margins means when viewed under the microscope, the tumor is completely surrounded by a layer of normal cells. This patient healed well and had a good outcome.

Looking back on the case, the surgeons suggest that a correct diagnosis could have been made if a portion of the nail bed had been removed and examined under the microscope before surgery. The patient may have still had the tip of the finger and the joint removed, but the fear of malignancy would have been put to rest before the procedure was done.
S. Alexander Rottgers, MD, et al. Subungual Extraosseous Chondroma in a Finger. In American Journal of Orthopedics. November 2008. Vol. 37. No. 11. pp. E 187-E190.