Particular histological features of a case of Sweet's syndrome induced by G-CSF

Background. Sweet's syndrome may occur during medullar aplasia, especially after treatment with exogenous growth factors such as G-CSF. In this context, Sweet's syndrome presents particular histological features that we detail in this observation. Case report. A 50 year-old man was treated for multiple myeloma with a mobilizating chemotherapy prior to autologous stem cell transplantation. Four days after the onset of G-CSF, he presented with a febrile generalized eruption of erythematous infiltrated lesions. Histological examination of a skin biopsy showed a neutrophilic infiltrate associated with atypical xanthomized histiocytes and vascular hyperplasia with marked endothelial turgescence.. Treatment with a short cause of oral corticosteroids was efficient. Discussion. The classical histological features of Sweet's syndrome consist in a dermal neutrophilic infiltrate with edema. in our patient, we noticed the presence of atypical histiocytes among the dermal neutrophilic infiltrate. These histiocytes are described in maculo-papular eruptions induced by G-CSF, and should not be confused with a malignant infiltrate associated with a hemopathy. Vascular hyperplasia may be related to the angiogenic properties of G-CSF. Knowledge of these histological features would enable clinicians and histologists to recognize the appropriate diagnosis.