Not all that coughs is Kochs.

Sarcoidosis is a chronic multi systemic granulomatous disease of unknown aetiology (cause). Because it is not common and presents with respiratory symptoms especially cough, it may often be misdiagnosed as Tuberculosis (Kochs disease) in our environment.
As with most diseases in medicine that the cause is unknown, genetics and environmental factors play important roles in its aetiology. T cells and B cells play important roles in its pathophysiology especially the former. Cytokines such as IL 1 and TNF alpha are upregulated in the disease. I jokingly tell my students that any condition with the aetiology unknown will usually have an interplay of genetic and environmental factors with subsequent release of cytokines. I also tell them that even if I do not know much about a condition…as long as the aetiology is uncertain, it will definitely be an interplay between genetic and environmental factors. With that….you can almost write about the pathophysiology of most of these conditions. It is more common in African-Americans and blacks and they often have more severe disease.

What are the ways sarcoidosis can present?
1. Asymptomatic….in 5% of cases
2. Non specific systemic symptoms – in 45% of cases. Like malaise, joint pains, fever.
3. Pulmonary symptoms – In a little more than 50% of cases such as cough, chest pain, difficulty breathing (called dyspnoea) especially on exertion and occasionally hemoptysis.
4. Skin manifestations which may be in form of –
a. Erythema nodosum – which is a form of inflammation of the subcutaneous tissue appearing as reddish or purple/dark colored pigmented induration usually on the lower limbs.
b. Lupus pernio – a raised purplish or reddish (usually appears dark in blacks) induration of the areas around the nose, cheeks, lips, ears and foreheads. It is the only PATHOGNOMONIC skin lesion of sarcoidosis.
c. Indurated plaques on the skin which may also occur in old scars (scar sarcoid).

5. Ocular – anterior and posterior uveitis, conjunctivitis amongst others. May lead to blindness.
6. Heart – Arrhythmias, heart failure.
7. Neurological – Cranial nerve palsies, aseptic meningitis amongst others.
8. Hypercalcemia with its symptoms such as kidney stones.

You can see that it can affect almost any system. It may be easier to diagnose if it involves the skin…that is if it gets to someone that can recognize it. If not.. a lot of patients spend months or even years before a diagnosis is made.

How is it diagnosed?
Chest Xray is central to diagnosis and depending on the stage…may be normal or show bilateral hilar adenopathy, pulmonary infiltrates or even fibrosis. Note that there are 4 stages of lung involvement.

High resolution CT.
Pulmonary function tests.
Serum ACE level is only 60% sensitive and 70% specific for sarcoidosis.
The most important way to do a definitive diagnosis is a biopsy of affected organ that can be biopsied. Please don’t mention eye biopsy 😊

Transbronchial biopsy, skin biopsy for histology can be done. Usually shows non-caseating granulomas (they’re usually naked granulomas). Stains must be done for mycobacterium (TB) and fungi as these are causes of other granulomatous skin conditions that may be confused with sarcoidosis. These stains are negative in sarcoidosis.

How do you treat? Depends on the stage.
Steroids, immunosuppressive, biologics. Lung transplantation may be necessary in advanced lung disease.

So….I hope you have learnt a thing or two about sarcoidosis. Can you give me two differentials for the skin lesions? I gave a clue in the writeup.

Remember……not all that coughs is Kochs😊.

If you’re not a medic and you read this, I’m sure you’re having tension type headache already. Not to worry….that slight cough you’re having is not likely sarcoidosis. Its not as common as that. So worry not.

For the medics, I hope I have piqued your interest enough to make you go and read more about sarcoidosis. A whole lot still left to learn. This is just a tip of the iceberg.

Any comments, questions or clarifications?