One man's irrepressible body odor was the result of a bacterial infection of his armpit hair, according to a new report of the case.
The 40-year-old man told his doctors he'd had armpit odor and "dirty" armpit hair for the last four years.
There was a "creamy yellow" substance on the man's armpit hairs. Looking at the hairs under the microscope, the doctors saw that the hairs were surrounded by an "opaque material" that was only on the hair surface.
The doctors diagnosed the man with trichomycosis axillaris, which is an infection of hair shafts caused by the bacteria Corynebacterium tenuis, the researchers said. The infection can produce yellow, black or red masses around hair shafts.
The bacteria tend to grow on hair in moist regions of the body — mostly armpit hair, but sometimes pubic hair.
The odor that comes with the condition is due, in part, to the ability of the bacteria to metabolize testosterone in sweat into smelly compounds, the researchers said.
The man had his armpit hair shaved, and was treated with aluminum chloride (used to treat sweating) as well as the antibiotic erythromycin. The odor went away several weeks later, his doctors said.
Previous research has found that humans, like other animals, might use scent to sniff out appropriate mates. In one study, women ranked the scent of men infected with gonorrhea as "putrid."
The report, described by researchers in Beijing and Madrid, is published Wednesday in the New England Journal of Medicine.
NBC News' Joy Jernigan contributed to this report.
More content from LiveScience: