Dermatologic Manifestations of Hypereosinophilic Syndrome Workup

Updated: Aug 21, 2019
  • Author: Felix Urman, MD; Chief Editor: Dirk M Elston, MD  more...
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Laboratory Studies


The eosinophil count is greater than 1.5 X 109/L. Eosinophils can exhibit structural abnormalities, such as cytoplasmic vacuolization and nuclear hypersegmentation. On a peripheral smear, eosinophils may be normal in appearance, but often some morphologic abnormalities, such as a decrease in granule number and size, are observed.

Neutrophilia is common, but bandemia is infrequent. Extremely high leukocyte counts and immature forms may indicate a leukemia and have a worse prognosis.

Leukocyte alkaline phosphatase levels can be elevated or decreased.

Of patients with hypereosinophilic syndrome (HES), 50% have anemia. Teardrop cells and nucleated erythrocytes can often be found on a peripheral smear.

Thrombocytopenia is seen in 31% of patients; however, 16% of patients have an elevated platelet count.

The erythrocyte sedimentation rate may be elevated.

Vitamin levels

Vitamin B-12 and vitamin B-12–binding protein levels may be elevated. [45]

Folate levels can be below the reference range.

Pleural fluid

This analysis typically reveals a transudate; however, exudative effusions containing eosinophils can be present.

Chromosome analysis  [46]

Chromosomal abnormalities are diverse, with the most common being aneuploidy.

The Philadelphia chromosome has occasionally been found.

Clonality of eosinophils has been observed.

Immunoglobulins levels

High immunoglobulin E (IgE) levels are found in 38% of patients. Elevations in immunoglobulin G (IgG), immunoglobulin A (IgA), and immunoglobulin M (IgM) levels are less common.

Urine analysis

Proteinuria, hematuria, albuminuria, and/or hyaline casts may be present.

Blood chemistry analysis

Renal and liver function test values can be elevated.

Gene studies

Martinaud et al reported a 49-year-old man with hypereosinophilic syndrome who had both a FIP1L1-PDGFRA fusion gene rearrangement and T-cell clonality. [6]


Imaging Studies

Cardiac studies

Echocardiography can be used to assess thrombus formation, fibrosis, pump function, and valvular dysfunction. [47] Mitral and tricuspid dysfunction may also be detected.

ECG often reveals T-wave inversion and can be used to evaluate arrhythmias.

Cardiac catheterization and angiography can be used to evaluate myocardial function and valvular dysfunction.

Pulmonary studies

Chest radiography and CT can demonstrate pleural effusions, pulmonary infiltrates and fibrosis, and cardiomegaly.

Neurologic studies

Head CT and MRI can reveal strokes; TIAs; and increased cerebrospinal fluid (CSF) pressure, particularly from inflammation of central nerve tissue.

Peripheral nerve conduction studies are useful in assessing neuropathies.

GI studies

Abdominal CT can be used to evaluate hepatosplenomegaly, the hepatic vein (Budd-Chiari syndrome), and intestinal infarction.

Angiography can be used to assess the mesenteric vascular supply when embolic disease is suspected.

Endoscopy and barium studies can be used to evaluate ulcerations.



Endocardial biopsy can help in diagnosing hypereosinophilic syndrome, particularly early in the disease when other cardiac signs and symptoms are not yet present. Right ventricular biopsy can be performed to evaluate for endomyocardial involvement.

Pleural fluid aspiration should be performed in patients with an effusion.

Bone marrow aspiration and biopsy, with evaluation of cytogenetics, can reveal myelofibrosis or a leukemia.

Because cutaneous lesions are nonspecific, skin biopsy may be necessary to confirm the diagnosis and to rule out other causes.

Fluorescein angiography may be performed even if patients do not have ocular symptoms. Fluorescein angiography has demonstrated that more than 50% of patients with hypereosinophilic syndrome have choroidal abnormalities, including patchy and delayed filling, and retinal vessel abnormalities.


Histologic Findings

The histopathologic findings vary. Several reports have noted microthrombi in blood vessels along with a variable superficial, deep, and interstitial perivascular infiltrate of eosinophils and other inflammatory cells. One report describing 3 patients linked an eosinophilic vasculitis to a recurrent purpuric rash. In a patient with multiple indurated plaques, a dermal infiltrate with eosinophils with flame figures was found. In eosinophilia with recurrent angioedema, a clinical syndrome thought to be a variant of hypereosinophilic syndrome, the infiltrate is primarily mononuclear with few eosinophils.

Biopsy samples of mucosal ulcerations typically demonstrate a mixed cell infiltrate without vasculitis.

Endocardial biopsy findings vary depending on the stage of the disease. In early disease, eosinophil infiltration with eosinophil microabscesses and myocardial necrosis are found. In advanced disease, fibrosis predominates.

In patients with neuropathy, peripheral nerve biopsy samples usually show axonal loss and no evidence of vasculitis or eosinophil infiltration.