TB or Not TB: The Weirdness that is Extra-Pulmonary Tuberculosis

By Rebecca Kreston | February 29, 2012 7:00 pm

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.

Patient Richard Pendlebery with extrapulmonary tuberculosis infection of the joints. He’s dapper aside from the flipper, no? Photograph taken by William H. Rhoads in Philadelphia circa 1866-98. Property of the College of Physicians of Philadelphia and the Mutter Museum. Click for source.

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.

An unidentified man suffering from Pott’s disease or extrapulmonary tuberculosis infection of the spine. Photo taken by John Mayall in 1877. Click for source.

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.

A young unidentified patient with a case of scrofula or cervical tuberculous lymphadenopathy. Infection is characterized by abscess formation of the lymph nodes in the neck. Image: Images from the History of Medicine (IHM). Click for source.

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.

Resources

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.

References

(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

ResearchBlogging.org 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

  • Colin

    So with something like Pott’s disase, what is actually happening with that poor man’s spine? Is the immune system attacking and killing near by cells in the hope of removing the TB infection, because I desparetly want to understand how theTB infection leads to such a painful looking condition? Likewise with ol’ flipper hand…

    • http://blogs.discovermagazine.com/bodyhorrors/ bodyhorrors

      OK Colin, I gotcha, don’t panic! Immunologists might complain that I’ve vastly vastly simplified this explanation of JUST WHAT IS GOING ON HERE and I would tell them something inappropriate that they can do with their interferon-gamma. I hope the following makes sense to you. Here you go:

      The thing about tuberculosis is that it’s not that tricky of an organism. Even though this microbe is hiding in a macrophage, other immune cells know this. These immune cells (neutrophils, macrophages, and lymphocytes or white blood T cells) identify the infected macrophage and attack him ferociously. The catch is that this TB+macrophage pair have usually hidden themselves somewhere, say, the vertebral disc in your spine or in the joints of your hand or your lymph nodes. So you have a situation where your immune cells are attacking this THING in a part of your body and churning up cellular debris and generally pissing off neighboring cells.

      When you have many TB+macrophage pairs in a location attracting all this negative attention from your immune system, we get something called “caseous necrosis”, a type of gross cell death in which healthy, happy cells comprising a bodily tissue die and turn the tissue into a kind of mushy cheese (I didn’t come up with the name OR the disease so don’t blame me for the gross description). It is a super intense form of tissue destruction caused by our own immunological cells. The effects of tuberculosis derive mostly from the host’s response (your body!) to infection, causing this shit show of cellular damage and death, not so much the microbes trouble-making (what we like to call its “virulence”). Your question “Is the immune system attacking and killing nearby cells in the hope of removing the TB infection” answered itself: pretty much!

      With Pott’s disease specifically, you have this TB+macrophage pair hiding in the interior of the vertebral disc (the epiphyseal cortex). When your immune cells decide to have this cellular moshpit of death in the vertebral disc, it can lead to a softening of the vertebral body, in turn leading to compression or collapse of the vertebral disc.

      Infection can spread beyond the vertebral disc and to the space between discs or between two adjacent discs. These two discs can become a caseating cheesy mess, and die, and then the vertebral section can collapse. Then your spine turns into the letter S, a backward C, lowercase J, or whatever Sesame Street letter you would like to decide upon.

      Don’t get tuberculosis!

  • Colin

    I think I just heard the crowd go, “oohhh, ouch” on that detailed description. But you know, what you just wrote was exactly the good horrorific detail I was hoping to hear about. I had to ask because I really had trouble wrapping my head around the scope of cellular damage that could be done in an effort to clear a highly persistant infection. To have enough cells killed to have the potential where spinal discs can collapse!? That is crazy.

    As for not getting TB, in talking With HIV/AIDS activists and TB opportunistic infections is one of the biggest concerns right now and is driving considerable attention towards developing TB vaccines. I think examples like this really drive the point home especially in a case like HIV where, while you don’t have the helper T cells, you still have the full complement of other spewing, mean, nasty immune cells. Have you seen or heard of any cases where this type of TB-associated cell death occurs in HIV patients?

    Finally, re-looking at that photo of the sesame street back, you can see how flushed his cheeks are, even in black and white. That poor kid has gotta be feeling many degrees of sick. Or, for sic Kings, you can imagine how all the jewels in the world are not going to make you feel any better…

  • http://blogs.oregonstate.edu/abouck Austin J. Bouck

    Extraordinarily entertaining post, you have a way with words, and I’d love a description of de-gloving or necrotic sloughing from you.

    Also good info for me, I had just written about blaming bovine TB on the badgers: http://blogs.oregonstate.edu/abouck/2012/02/15/badger-culling-in-the-u-k-step-one-cull-badgers-step-two-step-three-profit/

  • http://stormiidae.blogspot.com Storm

    An amazing read, including your detailed reply to Colin’s question. Thanks.

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Body Horrors

Body Horrors looks at the history, anthropology and geography of infectious diseases and parasites.

About Rebecca Kreston

Rebecca Kreston is an infectious disease scholar trained in microbiology and epidemiology. She obtained her Biology degree from Reed College and her Masters of Science in Tropical Medicine from Tulane University. She's lived in tropical jungles, beaches and deserts around the world and has been exposed to several of the diseases that she studies. She currently lives in New Orleans, is a first year medical student and regularly battles insects of the Diptera, Siphonaptera and Hymenoptera orders.

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