Is Rosai-Dorfman disease a reactve process? Detection of a MAP2K1 L115V mutation in a case of Rosai-Dorfman disease

Excerpt

Histiocytoses are rare disorders characterized by the accumulation of macrophages, dendritic cells, or monocyte-derived cells in various tissues and organs of children and adults [1]. In principle, histiocytic disorders can be subdivided into three groups: Langerhans cell (LC), non-LC and malignant histiocytoses (MH). Recently, a more detailed subdivision has been proposed [1], which defined five subgroups, of which one was dedicated to Rosai-Dorfman disease (RDD). RDD is a non-LC histiocytosis, which has been described as a distinct clinico-pathological entity almost 50 years ago [2]. Its etiology is still unknown but it is considered as reactive with a benign clinical course, particularly if involving solely lymph nodes [3]. Most cases occur idiopathic but some are associated with other disorders like IgG4-related diseases, the autoimmune lymphoproliferative syndrome or various autoimmune and hereditary conditions [3]. Patients present typically with a massive bilateral cervical lymphadenopathy accompanied by fever, night sweats, fatigue, and weight loss [1, 2]. RDD can also be observed at several extranodal sites, such as the skin and soft tissues, the nasal cavity, the bones, and the central nervous system. Thus, RDD is a heterogeneous entity, and it is recommended to distinguish classical cases with exclusive single or regional lymph node involvement from extranodal cases [1]. …