EOSINOPHILIA See also
Eosinophilia
GENERAL CLASSIFICATION OF
EOSINOPHILIC DISORDERS
Blood eosinophilia can be classified as either
- Familial Eosinophilia
or
- Acquired Eosinophilia
a. a primary process or
b. a secondary process,
depending on whether eosinophils are considered integral to the underlying disease.
Infectious causes
and noninfectious causes of secondary eosinophilia
are prevalent in underdeveloped and developed countries, respectively.
Primary eosinophilia occurs primarily in males and is considered clonal in the presence of either cytogenetic evidence or
bone marrow histological evidence of an otherwise defined neoplastic
hematologic disorder.
Otherwise, a
working diagnosis of idiopathic eosinophilia is made, and in
the presence of both sustained eosinophilia (AEC =1500
cells/µL for at least 6 months) and target organ damage (eg,
skin, heart, lung, nerve tissue), the process is subclassified
as hypereosinophilic syndrome (HES).
Causes of Hpereosinophilia:
- Allergy: hay fever, asthma, urtiacaria,
drug sensitivity
- Skin disorder: pemphigus,
dermatitis herpetiformis
- Parasitic: trichinosis, echinococcus
- Pulmonary infiltrate with eosinophilia
- Sarcoidosis
- Hypereosinophilic syndrome
- Adrenal insufficiency
- Malignancy: Hodgkin's disease, chronic myelogenous leukemia, mycosis fungoides,
pernicious anemia, polycythemia vera, malignancy of any type, esp. with metastases or
necrosis
- Connective tissue disease: RA, dermatomyositis,
periarteritis nodosa
- Idiopathic
Classification and Causes
of Blood Eosinophilia*
- Familial
- Acquired
- Secondary
- Infectious causes
- Tissue-invasive parasitosis (most common)
- Bacterial or viral infections
(rare)
- Noninfectious causes
- Drugs (sulfa, carbamazepine, etc)
- Toxins (associated with eosinophilia-myalgia syndrome, toxic oil syndrome,
etc)
- Allergy (asthma,
atopic dermatitis, etc)
- Idiopathic/autoimmune
inflammatory conditions
- Vasculitis (Churg-Strauss,
Wegener)
- Kimura disease
- Eosinophilic fasciitis
- Systemic sclerosis or
scleroderma
- Polyarteritis and other CTDs
- Sarcoidosis
- Inflammatory bowel disease
- Malignancy (metastatic cancer,
Hodgkin lymphoma)
- Endocrinopathies (
- Primary
- Clonal
- Acute leukemia
- Acute myeloid leukemia
- Acute lymphocytic leukemia
- Chronic myeloid disorder
- Molecularly defined chronic
myeloid disorder
- Bcr/Abl+ chronic myeloid leukemia
- PDGFRA-rearranged eosinophilic disorder
- PDGFRB-rearranged eosinophilic disorder
- Kit-mutated systemic mastocytosis
- 8p11 Syndrome
- Clinicopathologically defined chronic myeloid
disorder
- Myelodysplastic syndrome
- Myeloproliferative disorder
- Classic myeloproliferative
disorder (polycythemia vera,
etc)
- Atypical myeloproliferative
disorder
- Chronic eosinophilic
leukemia
- Systemic mastocytosis
- Chronic myelomonocytic
leukemia
- Unclassified myeloproliferative disorder
- Idiopathic
- HES
- Pre-HES
*CTD = connective
tissue disease; HES = hypereosinophilic syndrome;
PDGFR = platelet-derived growth factor receptor.
Idiopathic
Eosinophilia. :
When
both clinical and laboratory evaluations do not clearly identify either a
secondary or a clonal cause, a working diagnosis of
idiopathic eosinophilia is reasonable.
FAMILIAL EOSINOPHILIA
Familial eosinophilia is rare, and its genetic basis,
at least in some cases, may be similar to that of clonal
eosinophilia.
Primary
Eosinophilia.
Clonal Eosinophilia.
A diagnosis of clonal eosinophilia requires the
presence of either cytogenetic evidence or bone marrow morphologic evidence for
either acute leukemia or a chronic myeloid disorder (Table 1). Hematologic
disorders that can be accompanied by clonal eosinophilia include acute myeloid leukemia,62 acute lymphocytic leukemia,63 chronic myeloid leukemia
(CML),64 myelodysplastic syndrome,65 and both classic and
atypical cases of myeloproliferative disorders (MPDs).66,67 The
atypical MPD category includes chronic eosinophilic
leukemia (CEL),68
systemic mastocytosis (SM),69 and chronic myelomonocytic leukemia (CMML).70 Recent developments in the
molecular characterization of pathogenesis, in a subset of patients with clonal eosinophilia, have
identified activating mutations of 3 receptor tyrosine kinase
genes: PDGFRA, PDGFRB, and fibroblast growth factor receptor 1 (FGFR1).71
All patients with suspected
primary eosinophilia should undergo bone marrow
examination with cytogenetics.