Medical Mystery: A teenager with cough, mouth sores, and red eyes

The parents of a 16-year-old boy brought him to the emergency department with a cough that had lasted for three weeks, red eyes, and mouth ulcers. When he awoke that morning, the inside of his mouth was burning. He noticed that the whites of his eyes were bloodshot, and he had mouth sores so painful that he could not even swallow his saliva.

In the ED, the triage nurse found he had a low-grade fever of 100.8 degrees. He was coughing and his blood oxygen level was 90% (normal for a teenager is between 95 and 100%). The nurse gave him supplemental oxygen through a mask as well as pain medication to make him more comfortable.

In medicine, we try to put patients’ symptoms together under one “umbrella” diagnosis. But lung, mouth, and eye problems at the same time? The ED doctor who picked up the patient’s case knew that this one was not going to be run of the mill. As she dove into the history, she discovered that three weeks ago, the patient’s two siblings were also sick with coughs, but they lasted just one week. Respiratory infections can spread like wildfire in households and can worsen asthma or cause bronchitis or pneumonia; each of these problems can mean a lingering cough.

The first step in making these diagnoses is listening to the patient’s lungs with a stethoscope. Asthma and bronchitis can cause wheezing. Pneumonia can cause a crackling sound. But despite the patient’s cough and low oxygen level, his lung sounds were normal. Next, a chest x-ray was done. Again, normal.

Another test that can be helpful in finding the cause of a cough is a nasal swab. Outside of the ED, most primary care providers (PCPs) can test for common respiratory viruses including COVID-19, influenza A/B, and RSV. In pediatric EDs, a nasal swab can test for an expanded panel that covers a larger number of pathogens including mycoplasma pneumoniae. Mycoplasma‘s claim to fame is that it can cause “walking pneumonia” – nicknamed this because the infection is usually mild enough that individuals may walk around with it without knowing that they have it. It is a relatively common infection that is usually treated with a short course of antibiotics.

 The patient tested positive for mycoplasma. At last, the doctor thought, we’re getting somewhere.

Mycoplasma explained his lingering cough, but why did he have red eyes and mouth ulcers?

Though not as common as the cough, mycoplasma also can cause mucositis, an inflammatory condition affecting mucous membranes. The patient had ulcers visible in his mouth, but they can appear anywhere along the lining of the digestive tract from the mouth to the anus. The conjunctiva is a thin, transparent mucous membrane that lines the inside of the eyelid and covers the white of the eye (sclera). The patient also had conjunctivitis – eye redness in the sclera.

When mycoplasma causes so many symptoms it is known as mycoplasma induced rash and mucositis (MIRM). MIRM is a rare complication of mycoplasma infection, with patients usually reporting about a week of symptoms like a common cold before new symptoms such as conjunctivitis and/or mouth ulcers. They may also have painful urination (dysuria) because the urinary tract has similar mucosal linings. Luckily, the patient was spared from this complication. The good news is that patients’ symptoms are usually temporary and should get better with time and treatment with an antibiotic (usually azithromycin) taken by mouth.

Post-script: besides the antibiotic, the patient also required special prescriptions for repeated doses of Rita’s frozen ice and Starbucks Refresher drinks; a doctor has to do what a doctor has to do.

Our advice:

While coughs with common respiratory illnesses often linger for up to 2 weeks, if a cough is getting worse and/or if new symptoms develop, it is time to take your child to the doctor.

Grace Hogan is a second-year pediatric resident and Rima Himelstein is an adolescent medicine physician at Nemours Children’s Hospital, Delaware.