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Numbness of the Arm

A legendary but surprisingly docile pathogen takes hold in a young man

By Robert A Norman
Feb 1, 2002 6:00 AMNov 12, 2019 6:22 AM


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"Is there anything else that you can tell me about it? Does it itch? Is it painful?"

"No, not really," my patient said. Patrick was a quiet, thin man of 22. I asked him a few questions about himself. He told me he worked in the biology department of a local university and that he had come from Vietnam eight years ago. He had not traveled outside the United States since then. He had family in a nearby town and lived in an apartment off campus.

His problem was a small growth on his arm. It was about the size of a nickel, with little pigmentation and ill-defined borders. He told me he'd had it for about eight months. I asked him if there were any other trouble spots. He said he also had a rash on his left elbow that got slightly itchy on occasion. He also complained of a rash on the left side of his face. It, too, was about the size of a nickel, and it had been there for a couple of months, he said. I could see that the spot on his left elbow was irregular and irritated. I noticed some slight redness near the growth.

I was going to recommend a biopsy when he suddenly spoke up: "It does feel kind of numb sometimes."

That's when a bell began ringing in my head. I had seen this condition before, 10 or more years ago. That patient's growth developed somewhat differently, but the sensation of numbness was the same.

I explained that I would need a biopsy to confirm my diagnosis. Patrick nodded his head and signed the consent form. I proceeded to remove a bit of skin. When I was finished, I wrote down what I suspected on the biopsy report. I instructed Patrick on how to care for the biopsy site, arranged for a follow-up visit, and sent him home.

A couple of days later, the dermatopathologist called me up and confirmed my hunch. "First time I've seen this," he said. "Lepromatous leprosy."

The next day I reviewed a copy of the slide containing the biopsy. Among the skin cells were numerous dark spots: the bacilli of Mycobacterium leprae. As required by Florida law, I reported the case to the health department.

M. leprae was first identified as the cause of leprosy by a Norwegian doctor, G. Armauer Hansen, in 1873. Although leprosy is often thought of as a disease of the tropics, it has been historically widespread in regions as diverse as Iceland, Scandinavia, North Korea, Japan, and India. An even more common misconception is that leprosy is highly contagious. In fact, most people exposed to the bacterium—which is thought to spread through respiratory droplets—can easily fend it off. Only in some people, for reasons that are still unknown, does the bacterium take hold.

Once an infection is established, it can manifest itself in a variety of ways. In lepromatous leprosy, the bacterium spreads widely beneath the skin and throughout the body. In tuberculoid leprosy, the peripheral nerves of the extremities can become permanently damaged. In borderline leprosy, patients show signs of both lepromatous and tuberculoid leprosy.

The reason for the different forms has to do with how an individual's immune system responds to the infection. Immune cells called macrophages normally consume the bacterium, which cannot migrate and releases no toxins. The symptoms of leprosy occur because in some cases the macrophages cannot always dispose of M. leprae. In tuberculoid leprosy, the immune system manages to isolate the bacteria by walling them off in distinct lesions of infected macrophages. In lepromatous leprosy, the bacterium accumulates and spreads not only in skin cells but also throughout the body. Because the bacterium prefers cooler temperatures, lesions tend to be most common in the skin and extremities.

Left untreated, the disease can form abscesses in the skin and trigger nerve damage and arthritis. In advanced untreated cases, patients can lose fingers and toes because numbness in the extremities puts them at risk for burns or injuries. Fortunately, most leprosy cases respond very well to treatment. The drug rifampin kills 99.98 percent of leprosy bacilli within a few days.

I teamed up with an infectious disease group to treat Patrick. He was put on antibiotics: dapsone, 100 mg every day, along with rifampin, 600 mg a day. We gave him prednisone, an oral steroid, to curb the inflammation. Because liver enzymes rose during treatment—a sign of drug toxicity—we decided he needed a different mix of drugs. After consulting with doctors from the Centers for Disease Control and Prevention, we discontinued rifampin and added Clofazamine, which fights both bacteria and inflammation.

Still, this case proved difficult to treat. Patrick continued to have adverse reactions. He also missed several appointments and said he couldn't afford the medications. Meanwhile, he developed more reactions, with pain and swelling on the face, particularly on the right cheek. He continued to do poorly, and his liver enzymes continued to rise. His total bilirubin, a key liver pigment, was 6.6; normal is zero to 1.3.

After a few months the bilirubin level went down to 3.2 and continued to fall. But the patient resisted treatment, and he continued to have brawny, round, inflamed lesions, with swelling and redness on his arms and face. We consulted a specialist at the National Hansen's Disease Center. He told us that we should increase his steroids to bring down the swelling.

Patrick showed a surprising lack of concern about his condition. He was clearly aware of his problem and may have witnessed it as a youngster in Vietnam. The last time I talked with him, he was getting treated by the infectious disease specialists to whom I had referred him. I hoped he was doing better. I felt sure that if he had cooperated more fully at the beginning, he would have enjoyed more rapid and effective results.

Since 1950, the estimated number of leprosy cases around the world has fallen from 15 million to perhaps 2 million. In the United States, the disease is rare: There are only about 3,000 cases. Still, leprosy's peculiarities frustrate researchers. Since the 1940s, we've had drugs to treat the disease, but efforts to create a vaccine have failed. An effective vaccine could eradicate the disease, which remains a significant problem in some regions. India, Myanmar, and Nepal, for example, are home to 70 percent of leprosy patients.

Given the rarity of leprosy in the United States, it seemed both strange and lucky that I had seen leprosy twice in my 20-year career. If I had not seen it the first time, I would not have recognized it the second time.

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