Hypereosinophile Dermatitis

Bullous pemphigoid-like rash revealing hypereosinophilic syndrome

Hypereosinophilic syndrome (HES) is a rare haematologic disorder characterised by unexplained, persistent eosinophilia with organ involvement. We report the case of a 74-year-old patient who presented with a pemphigoid-like bullous rash as the only manifestation of an HES. This report highlights the importance of the dermatological manifestations of this potentially life-threating condition that may initially present as a skin-limited disease. Bullous pemphigoid (BP) is a very common autoimmune blistering dermatosis that may share common clinical and histological features or associate with an HES. HES should be considered when patients diagnosed with BP demonstrate atypical course under corticosteroids and/or recalcitrant blood eosinophilia.

Hypereosinophilic dermatitis: generalised lichenification and gyrate erythema as the sole manifestation of idiopathic hypereosinophilic syndrome

A 22-year-old female presented with generalised lichenification and severe pruritus, along with multiple annular papules and concentric plaques over trunk and extremities for the last 3 years. Her haematological investigations revealed leucocytosis with peripheral blood eosinophilia and raised serum IgE levels. Skin biopsy showed perivascular and interstitial infiltrate of eosinophils and lymphocytes in the dermis. Bone marrow examination showed myeloid hypercellularity with increased number of eosinophils, but no atypical cells. Cytogenetic studies did not reveal any chromosomal alterations. No systemic involvement was found on imaging. A diagnosis of idiopathic skin-limited hypereosinophilic syndrome was made. She was treated with tapering doses of oral prednisolone and weekly methotrexate with significant improvement in skin lesions and pruritus in 2 months, which was maintained at 7-month follow-up.

Current topical and systemic therapies for itch

Itch is a common distressing symptom which may be caused by multifactorial aetiologies including inflammatory skin diseases, systemic diseases, neuropathic conditions and psychogenic disorders. Itch is a term used synonymously with pruritus and is defined as acute if it lasts less than 6 weeks or chronic if it persists for more than 6 weeks. It can have the same impact on the quality of life as chronic pain and shares many of the same pathophysiological pathways. Depending on the aetiology of the itch, different pathogenic mechanisms have been postulated with a number of mediators identified. These include histamine, leukotrienes, proteases, neuropeptides, cytokines and opioids, which may activate peripheral itch-mediating C-fibres via receptors on the nerve terminals and central neuronal pathways. Therefore, there is no single universally effective anti-itch treatment available. First-line treatments for itch include topical therapies, such as emollients, mild cleansers (low pH), topical anaesthetics, steroids, calcineurin inhibitors and coolants (menthol). Treatment with systemic therapies can vary according to the aetiology of the chronic itch. Non-sedating antihistamines are helpful in conditions such as urticaria where the itch is primarily histamine mediated. Although the itch of eczema is not mediated by histamine, sedating antihistamines at night are helpful to break the itch-scratch cycle. Chronic itch may also be treated with other systemic therapies, such as anticonvulsants, antidepressants as well as mu-opioid antagonists, kappa-opioid agonists and phototherapy, depending on the cause of the itch. This article summarises the topical and systemic therapies available with our current understanding of the pathophysiology of itch.