Thread by @nihardesai7

Hey #medicine residents !!

Time to talk about EOSINOPHILS today. Not as common a consult as thrombocytopenia and anemia but important nonetheless.

A short 🧵 to touch upon all things eosinophilia 👇🏻

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Before we go any further, it's important to know this

🩸Eosinophil ≥ 500 is ABNORMAL

Eosinophil is a predominantly tissue dwelling cell so 🩸 eosinophil DON'T correlate with tissue damage 🤷‍♂️

We see a few patients with ⤴️⤴️Eos and no 🫀🫁 injury !!

Where do eosinophils come from?

Short answer: Bone Marrow

They are cells of the granulocytic lineage, siblings of neutrophils and basophils, children of the myeloblast (image👇🏻)

IL5 is the cytokine responsible for it's production, important to know because we have anti IL5 mAb

Why do we care about ⤴️⤴️ eosinophils?

Eos are GRANULAR cells and the granules contain toxic material.

⤴️Eos=⤴️ degranulation=⤴️toxic contents=🫁🫀🧠damage !!

Lots of reasons to bother 🙏🏻

Basics out of the way, let's start with the clinical bit.

What's your approach for ⤴️ eosinophils?

Start with a HISTORY 👇🏻

Drug history is very IMPORTANT. Always ask about complementary drug intake. This could be recent or remote.

Trust me, it's very important 🙏🏻

So what are the other causes of ⤴️Eos?

•Allergies
•Parasitic infections
•Malignancies
•Immune disorders

The list is long and can be easily found over the internet !!

What organs are most often affected??

•Skin
•🫁
•♥️
•🧠
•GI tract

Ask if the patient has a rash, cough, wheezing, palpitations, dyspnoea, diarrhoea etc.

On examination, look for enlarged nodes, liver and spleen !

These symptoms mean there's end organ damage and one needs to act quickly.

PERSISTENT ⤴️ eosinophils (≥1500/mcL) AND end organ damage = HES (Hypereosinophilic syndrome)

This could be d/t any cause and HES ≠ malignancy all the time.

i.e. the degree of ⤴️⤴️≠malignant cause.

HES is a syndrome, one has to find the underlying cause.

HES could be d/t a myeloid neoplasm (M-HES), clonal lymphocytes (T-HES) or even be familial.

But most often our investigations don't reveal anything and we leave it at idiopathic HES 😭

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Why is it important to recognise the underlying cause??

Well, to treat and prognosticate better.

M-HES for example is treated differently, it responds to imatinib and responds poorly to steroids 🤷‍♂️

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M-HES is due to a chromosomal rearrangement involving FIP1L1-PDGFRa, can be tested for by FISH.

Also a/w ⤴️ vitamin B12 and ⤴️tryptase, most often with splenomegaly.

If you suspect this, call your hematologist!!

More often than not, eosinophilia will be transient and secondary to drugs/infections. Will resolve with appropriate Rx and drug withdrawal 💪

What if it doesn't ??

Read along 👇🏻👇🏻

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Let's RECAPITULATE 👇🏻

•Hypereosinophila ≥ 1500/mcL
•HES is above + organ damage
•HES has many varieties, some are cancers
•MC organs involved 🫁♥️🧠, skin, GI tract
•Mostly transient, sec to infections/drugs
•If persistent, involve a hematologist

Moving on👇🏻

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Now let's talk LABS ✅

What do we order beyond the usual blood counts, metabolic panel, infection screen etc?

It depends on the symptoms and what the underlying suspected disease is !

Think of M-HES in a young male w/ ♥️ involvement, L-HES involves more of skin.

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EGPA will present with 🫁 findings so tests depend upon clinical suspicious.

But we test with 2 things in mind, identifying the UNDERLYING CAUSE of HES and tests to IDENTIFY END ORGAN DAMAGE (eg Troponin)

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When do we treat URGENTLY ??

When there's severe organ damage like respiratory distress, other ♥️/🧠 symptoms !

That's just common sense🙏🏻

Admit and treat immediately.

Steroids are magical 🪄🪄🪄

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For most other situations, it's ok to initiate Rx on an outpatient basis.

Starting steroids before establishing a diagnosis is tricky business, must be avoided. It can change everything. Tread very carefully 🙏🏻

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If I urgently need to ⤵️ eosinophils, I use hydroxyurea while awaiting the test results.

Once the results are in, treat accordingly.

M-HES is treated with imatinib as imatinib 🚫PDGFR in addition to BCR-ABL1. The dose used here is <<CML (100mg OD)

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If M-HES has ♥️ symptoms (usually does), start imatinib + steroids to avoid fatal myocardial necrosis 🙏🏻

For all other HES variants, the treatment is CORTICOSTEROID 🪄🪄🪄

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The usual corticosteroid used is prednisolone at 1mg/kg.

Some use higher doses of methyl-pred like 1gm/d x 3 days. I use this dose only if severe symptoms or underlying autoimmune disease is the cause of HES.

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How long to continue steroids??

Tricky question, continue till ANC ≤1500 & symptoms resolved and then taper.

If the patient needs >10mg steroids for the same, start a steroid sparing drug !!

What are those?
•Hydroxyurea
•Interferon a
•Mepolizumab

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Mepolizumab is an anti IL-5 monoclonal antibody

IL5 is required for eosinophil production so mepolizumab 🚫this.

Dosed at 300mg s/c once a month but it's not available in 🇮🇳 so our options are hydroxyurea > IFNa.

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SUMMARY slide 💪💪

•Eos ≥1500/mcL w/ organ damage = HES

•HES has many variants

•M-HES treated differently from the rest (imatinib > steroids)

•All other HES variants are treated w/ corticosteroids initially f/b steroid sparing drugs if needed.

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•Very often the underlying cause won't be identified = idiopathic HES.

If you read this far and learnt something, do share this thread 🧵

As always, thank you 🙏🏻🙏🏻

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End.