HES, a prolonged eosinophilia of unidentified cause, was described by Hardy and
Anderson in 1968 and today, it is known as the idiopathic HES (iHES) (7). Although
the true prevalence of the syndrome is unknown, approximately, HE-incidence
could be estimated between 0.36 and 6.3 per 100000 (8) and all-inclusive
evaluations demonstrate that more than 50% of patients are in the group (iHES).
maximum age of the diagnosis is 20-50 years and and is seen mainly in men, but the severity of this syndrome is equal between the
sexes (10). HES is considered as a systemic disease which could be deadly via eosinophilic
infiltration into vital organs such as heart and lungs (11). Pulmonary
involvement can occur for two causes: primary involvement may derive from eosinophilia
infiltration of the lungs and secondary involvement result from heart failure
in pumping function (known as congestive heart
failure) and emboli due to deep vein thrombosis or a right ventricular mass (12).
Investigatins were demonstrated that pulmonary
involvement, one of the principal cause of death of
hypereosinophilic syndrome, can exist in more than 40% of cases (12). Also, Skin
is the essential tissue who is involved in HES. Skin lesions could occur in
over 50% HES-positive cases that the erythematous pruritic papules, nodules, Angio-edematous
and Mucosal urticaria is most common skin complications (15, 16). In case 1, Unlike
the reported cases, the hypopigmented lesions
on the skin of the hand differentiated him. The
exact cause has not yet been reported, but it is likely to be associated with
increased cytolysis of eosinophils and their degranulation effects in the skin (8).
However, the main cause
of eosinophilia in HES remains unknown, recently, FIP1L1/PDGFRA
(Fip1-like1/platelet-derived growth factor receptor alpha) fusion existence has
been approved in this syndrome (7, 11). Regarding HES poor prognosis, FIP1L1/PDGFRA
mutation, as a tyrosine kinase, could be targeted via tyrosine kinase
inhibitors (Imatinib) and improve HES patient’s treatment (7, 11).Typically,
corticosteroids such as prednisone are utilized for HES therapy which could
immediately reduce the eosinophil count and the improved reversible organ
dysfunction quickly (17). The unique features of case 2 were pulmonary involvement and
skin lesions and both of them, were identified and so far, selective therapies
have been effective.