Image Gallery: Hairy-cell leukaemia presenting with Sweet syndrome

New Practical Aspects of Sweet Syndrome

Sweet syndrome (SS), or acute febrile neutrophilic dermatosis, is an inflammatory, non-infectious skin reaction characterized clinically by tender, erythematous papules/plaques/pustules/nodules commonly appearing on the upper limbs, trunk, and head and neck; histologically, SS is characterized by dense neutrophilic infiltrate in the dermis. SS is accompanied by fever; an elevation of inflammatory markers (e.g., erythrocyte sedimentation rate, C reactive protein) in serum may also be observed. Although most cases of SS are idiopathic, SS also occurs in the setting of malignancy or following administration of an associated drug. SS has also been reported in association with pregnancy and a burgeoning list of infectious (most commonly upper respiratory tract infections) and inflammatory diseases; likewise, the litany of possible iatrogenic triggers has also grown. Over the past several years, a wider spectrum of SS presentation has been realized, with several reports highlighting novel clinical and histological variants. Corticosteroids continue to be efficacious first-line therapy for the majority of patients with SS, although novel steroid-sparing agents have been recently added to the therapeutic armamentarium against refractory SS. New mechanisms of SS induction have also been recognized, although the precise etiology of SS still remains elusive. Here, we catalogue the various clinical and histological presentations of SS, summarize recently reported disease associations and iatrogenic triggers, and review treatment options. We also attempt to frame the findings of this review in the context of established and emerging paradigms of SS pathogenesis.

Skin changes in hairy cell leukemia

Skin lesions have been reported in about 10–12% of hairy cell leukemia (HCL) patients. Most are etiologically related to autoimmune or infectious processes, although secondary cutaneous neoplasms and drug-induced lesions are also reported. However, leukemia cutis with the direct infiltration of the skin by leukemic cells is extremely rare in HCL patients. This paper reviews the epidemiology, pathogenesis, clinical symptoms, diagnosis, and approach to treating skin lesions in HCL. A literature review of the MEDLINE database for articles in English concerning hairy cell leukemia, skin lesions, leukemia cutis, adverse events, infectious, cutaneous, drug reactions, neutrophilic dermatoses, secondary neoplasms, and vasculitis was conducted via PubMed. Publications from January 1980 to September 2020 were scrutinized. Additional relevant publications were obtained by reviewing the references from the chosen articles.