Mast Cell Neoplasms Jonathan J. Davick Catherine G. Chung Liaqat Ali MASTOCYTOMA Definition A form of cutaneous mastocytosis characterized by the presence of one or a few solitary cutaneous tumors…

Schnitzler Syndrome Viktoryia Kazlouskaya Jacqueline M. Junkins-Hopkins INTRODUCTION Schnitzler syndrome (SchS) is a rare and often underreported chronic multisystem disorder, diagnosed on the basis of the presence of two major…

Pyoderma Gangrenosum Campbell L. Stewart Roberto Novoa DEFINITION Pyoderma gangrenosum (PG) is a rare, ulcerative cutaneous disease of unknown etiology. Its diagnosis critically relies upon the exclusion of other causes…

Granuloma Annulare–Like Reactions Karolyn A. Wanat Misha Rosenbach INTRODUCTION Cutaneous granulomatous inflammation has been reported in association with underlying lymphoproliferative disorders in primarily two patterns: granulomas within or surrounding the…

Cryoglobulinemia Alejandro A. Gru DEFINITION Cryoglobulins are abnormal serum immunoglobulins that reversibly precipitate at low temperature. Two forms of cryoglobulinemias are distinguished based on the composition of the cryoglobulins and…

Paraneoplastic Pemphigus Milda Chmieliauskaite Faizan Alawi INTRODUCTION Paraneoplastic pemphigus (PNP) is an autoimmune vesiculobullous disorder.1 PNP was first described in 1990 as a distinct clinical entity different from pemphigus vulgaris…

Vasculitis Alejandro A. Gru INTRODUCTION Vasculitis refers to a heterogeneous group of disorders characterized by vessel inflammation.1 The clinical manifestations range from locoregional ischemic and purpuric injuries to systemic disease….

Wells Syndrome (Eosinophilic Cellulitis) Melinda Jen Adam I. Rubin INTRODUCTION First described in 1971 by George Wells, Wells syndrome (or eosinophilic cellulitis) is an uncommon, recurrent inflammatory dermatosis of unknown…

Sweet and Histiocytoid Sweet Syndrome Viktoryia Kazlouskaya Jacqueline M. Junkins-Hopkins DEFINITION Sweet syndrome (SS), also known as acute neutrophilic dermatosis, is a predominantly neutrophilic disorder, frequently associated with systemic involvement….

Eosinophilic Dermatosis of Hematologic Malignancy Joya Sahu Jason B. Lee Eosinophilic dermatosis may be encountered in the setting of various hematologic malignancies and hematologic disorders, including blood dyscrasias and myelodysplastic…