"What's this?" Bernstein asked, pointing to a red lesion on the side of the patient's thumb. The patient had burned it a few months earlier and it healed very slowly. It got infected and it took two rounds of antibiotics to clear up.
Bernstein reviewed the tests received from Vitale. All blood tests were normal. And the imaging only showed the swelling and fluid around the tendons and the joint. This could be inflammatory arthritis; There were some who didn't show up in blood tests. But when Bernstein saw this lesion, he worried that it might be an infection. And there was one infection that she was particularly concerned about.
"Have you been cleaning a fish lately?" asked the doctor. The question surprised the patient. Yes, she did. Months earlier, before all of this had started, her daughter had ordered three branzinos from the market. Ordinarily the patient's husband, an avid fisherman, would have cleaned them, but he had just undergone shoulder surgery. So he trained from the sidelines as she climbed and cleaned it. It was a disaster. When she finished there were fish scales and drops of blood everywhere. But the fish just cooked wonderfully.
Bernstein nodded. There were several tiny bumps around the patient's thumb that appeared to extend from the tip of the thumb to the wrist. Bernstein recognized this as a sign of a rare infection that was caught by fish – often while scaling. In fact, this infection, caused by a cousin of tuberculosis, Mycobacterium marinum (M.M.), is sometimes referred to as fishmonger disease. Bernstein had seen it years before. The organism enters the body through a cut or scratch in the skin. Once in, it grows slowly and then migrates through the body via the lymphatic system, which is why the disease's characteristic nodules and ulcers often appear in the lines formed by the lymphatic vessels below. Bernstein suspected that the infection in the thumb had spread to the patient's hand and wrist – and that the steroids the patient was taking contributed more to the atypical swelling of the infection than to the usual nodules.
Even so, it was a rare disease; There were maybe three cases per million people a year. Unusual joint diseases were much more likely. Bernstein ordered some special blood tests and an ultrasound of the wrist to see if there was any fluid that could be tapped. If this was an infection, the beetle could often be bred from these fluids. And she referred the patient to another doctor, Gavin McLeod, an infectious disease specialist.
McLeod saw the patient that weekend. He wasn't sure if this was Mycobacterium marinum, but it was a compelling story. He stopped the prednisone and colchicine. These drugs stop inflammation by slowing the work of white blood cells. And he gave the woman two antibiotics to treat M.M. It is best to start treating this infection before the diagnosis is made.