Eosinophilia (Peripheral)

DDx for peripheral blood eosinophilia:

· Normally, eosinophils only account for 1-3% of peripheral blood leukocytes; eosinophilia is defined as >350 cells/mm (mild=350-1500, mod=1,500-5,000, severe >5000)

 

Approach to Peripheral Eosinophilia:

·         medication history

·         travel history

·         allergy history

·         constitutional sxs

·         CBC w/ diff, peripheral smear

·         IgE level

·         HIV

·         Stool O&P

·         parasite serologies

• If no reactive cause identified on initial screen:

  ·         PFTs

  ·         EKG + echo

  ·         CT chest/abd

  ·         BM bx + cytogenetics

  ·         tissue biopsy

 

Two Way to Remember the Differential

 

· Consider two categories: primary or idiopathic vs. reactive/secondary causes

o   Primary: clonal proliferation of eos from abnl bone marrow  

· AML, ALL, MDS, systemic mastocytosis, FIP1L1-PDGFRA fusion

· Hypereosinophilic syndrome (HES): idiopathic, a diagnosis of exclusion

o   Secondary: reactive to infectious and noninfectious causes

· Infectious: parasitic (esp helminth) infxns are the most common cause worldwide (ie. strongyloides, schistosomiasis etc.); viral (HIV); fungal (cocci, ABPA); bacterial (lyme dz)

· Drug reactions: sulfa, antiepileptics etc.

· Allergic: asthma, atopy, allergic rhinitis

· Malignancy: Hodgkin’s dz, NH lymphoma, metastatic solid tumors

· Autoimmune: Churgg-Strauss, Wegener’s, eosinophilic fasciitis, sarcoid

· Endocrine: Addison’s disease, adrenal hemorrhage  

 

Another way to look at the differential using a mnemonic:

- Use NAACP

 

• N: neoplasm: CML, mycosis fungoides, Hodgkin's and solid tumors (lung, stomach, pancreas, uterus, ovary)
• A: allergic reaction and allergies : commonly ASA, PCN, cephalosporins, sulfa drugs; eczema, asthma, hay fever, pemphigus
• A: adrenal insufficiency
• C: collagen vascular disease
• P: parasites: specifically helminthic infections: strongyloides, hookworm, toxocara canis

 

Other infectious things to keep on your list are aspergillus, cocci.

There are hypereosinophilic syndromes as well.

 

Pearl:

In contrast to the multicellular helminthic parasites, infection with single-celled protozoan parasites (giarida and E histolytica) do NOT cause peripheral eosinophilia.

Exceptions: isospora belli and D. fragilis.

 

Strongyloides is a nematode helminth (same class as pinworm, filariasis, oncho).

Tremadtoes, such as schisto, are flukes.

Cestaodes (tapeworm).

 

 

 

(Katharine Cheung MD, 1/27/11)

(Victoria Kelly MD, 1/4/11)