I like wild plot twists in my novels, remixes of my favorite songs and food with unexpected, exotic flavors. Needless to say, I also love hearing of cases where an infectious disease takes an unpredictable turn, appearing where it traditionally does not. And we have quite the curve-ball with Mycobacterium tuberculosis, a microbe with itinerant tendencies that materializes in some surprising anatomical locales.
Tuberculosis (TB) is in the big league of the leading infectious diseases that cause profound morbidity and mortality throughout the world. We all know this, yes? When we think of TB, we think of the frail poet John Keats, sticky handkerchiefs, bloody loogies, and wracking wet coughs. But for a microbe that we customarily associate with the lungs, this guy can really do a corporeal tour, appearing in such disparate locations as the spine, joints, intestines, and skin. In fact, it’s not that uncommon. Extra-pulmonary TB (EPTB) is responsible for 15 to 20% of all cases of TB, and can increase to up to 50% for those who are severely immunocompromised, as is the case with AIDS patients (1).
We often think of microbes and parasites as uniquely adapted to whichever locale in which they cause disease. But TB can be rather laissez faire about its home base as it lives rather comfortably within the peripatetic macrophage. Following inhalation of the rod-shaped microbe, the bacterium is phagocytized by a macrophage in the alveoli of the lung, which can then travel into the blood stream or into the lymph nodes via lymph. This so-called “lymphohematogenous seeding” of the bacteria spreads the microbes from their pulmonary location to other distant sites of the body. Like pollen floating in the wind, these hardy microbes traverse and populate new foreign lands. Ultimately, the bacteria + macrophage pair will lodge within a tissue that attracts the attention of the immune response. This condition is known as EPTB, disseminated TB or miliary TB. Indeed, that pollen metaphor may not be too far from fact: the term “miliary TB” derives from the appearance of the small, discretely formed tuberculoid nodes on MRIs and X-rays as tiny millet seeds seasoned throughout the organ of its choice.
EPTB can manifest itself in nearly every type of organ system of the body, though the most common sites are the lymph nodes, urinary tract and reproductive system, meninges of the brain, bones and joints, pleural cavity, skin, and peritoneal cavity. Some of these localized infections have acquired their own proprietary name: Pott’s disease for spinal TB, lupus vulgaris for TB of the skin, and scrofula for infected lymph nodes located in the neck/cervical region (or if you’re fancy: cervical tuberculous lymphadenopathy).
The point is: tuberculosis is not exclusively a respiratory disease but an opportunistic pathogen capable of infecting pretty much any organ in the body. It’s happy anywhere, sitting in its macrophagic throne pissing off the immune system with its infuriating presence and forming graulomas. It’s not only impressive but unique and weird.
It can get weirder: it seems that the serial monogamist King Henry VIII of England, as well as other less romantically inclined English and French monarchs between the 1200 to 1700s, had an intimate relationship with scrofula, the cervical lymphadenopathy form of TB (2). At the time, there existed a strong conviction that divinely appointed sovereigns could cash in on that holiness and, with a “royal touch”, cure scrofula sufferers. At the time, scrofula was considered any old disease with a prominent glandular presentation around the facial and cervical region, tuberculoid or not, and I imagine King Henry had quite the encyclopedic tour of illnesses (goiters! tumors! mumps!) during his time of curative prowess. Didn’t seem to do much of anything to temper his roving philandering eyes but, alas, libido is a powerful, powerful thing. As such, this quirk of history earned scrofula the moniker, the “King’s Evil”. Share that historical nugget at your next cocktail party!
EPTB can be tricky to diagnose as its a great disease mimicker, a lyrebird of an illness. Because the clinical presentation is so non-specific, so vague, it can be many years before a diagnosis of EPTB has definitively been made (3). Physicians must be on their toes in considering an individual’s risk factors for EPTB: history of travel, birthplace, ethnicity, sex and age. Aside from appearing most commonly in those infected with HIV/AIDS, it is also prevalent among young children and tends to infect women in greater numbers for unknown reasons .
As if we don’t already have to wonder about mites, toxoplasmosis and herpes lurking undetected in our bodies, now you can fret over possible extrapulmonary infection with that odd vagabond M. tuberculosis. You’re welcome.
Editor’s Note: Body Horrors has been quiet for the month of February in preparation for, celebration of and recuperation from Carnival Season and Mardi Gras in New Orleans, LA. My sincere apologies for my extended absence. If it makes you feel better, I was having the time of my life. I’m back now.
Wanna get deep into every clinical presentation of EPTB that has ever occurred? This exhaustive 38-page review is FREE with lots of pictures.
Jules Talrich was a popular anatomical model maker in the 1850s using wax and plaster to model various diseases and disfigurements. The Frenchman, who served as the official model maker for the Faculty of Medicine of Paris, currently has a number of his anatomical waxes peppered throughout medical museums around the world. This life-like wax model dating from the 1890s and now living at the National Museum of Health & Medicine in Washington, DC shows a man with a rather serious scrofula infection.
(1) Sharma SK & Mohan A. (2004) Extrapulmonary tuberculosis. Indian J Med Res. 120(4):316-53
(2) Barlow F. (1980 )The King’s Evil. Eng Hist Rev. 95(374): 3-27
(3) Dolberg OT, Schlaeffer F, Greene VW, & Alkan ML. (1991) Extrapulmonary Tuberculosis in an Immigrant Society: Clinical and Demographic Aspects of 92 Cases. Rev of Infect Dis. 13(1): 177-179
Dolberg OT, Schlaeffer F, Greene VW, & Alkan ML (1991). Extrapulmonary tuberculosis in an immigrant society: clinical and demographic aspects of 92 cases. Reviews of infectious diseases, 13 (1), 177-9 PMID: 2017620