Dan Med J ϧϫ/ϥ March ϤϢϣϤ DANISH MEDICAL JOURNAL ϣ ABSTRACT INTRODUCTION: The mast cell lives a hidden life, but it is implicated in several physiological reactions. Its ability to react to different stimuli impacts a variety of conditions such as asthma, atopic dermatitis, urticaria and anaphylaxis. It is not until recent decades that the evolution of the cell has been described and its fascinating biology has only recently been depicted. We here give a review of systemic mastocytosis in regards to cell biology, diagnostic ap- proaches and clinical practice. METHODS: A search was made in PubMed in August 2011 entering the keywords: mastocytosis, (systemic, cutaneous, aggressive), mast cell leukaemia, mast cell sarcoma, chromosome, mutation, haematology and treatment. RESULTS: Mastocytosis is characterized by an abnormal proliferation of mast cells, which accumulate in one or several organ systems, primarily the skin and bone marrow. The disease is clinically heterogeneous and varies from a relatively benign condition with isolated cutaneous lesions to a very aggressive systemic condition with a grave prog- nosis. The condition affects men and women equally. Chil- dren are especially affected by the cutaneous form. In most children, the condition will improve or remit spontaneously before adulthood. Mastocytosis in adults, however, is more often systemic and tends to persist. CONCLUSION: Patients with mastocytosis represent a het- ero geneous group in terms of clinical presentation, man- agement and prognosis. Furthermore, a range of medical specialties serve as the primary entrance to health services, which can be a challenge in respect of achieving uniform management. In order to improve diagnostics and manage- ment of systemic mastocytosis, the European Competence Network on Mastocytosis has been established. Patients under suspicion of systemic mastocytosis should be con- ferred with or referred to a haematological and a dermato- logical/allergological department. The mast cell lives a hidden life, but plays an important role in many physiological processes. The cell’s ability to react on various stimuli is demonstrated by its implica- tion in a wide range of conditions such as asthma, rhini- tis, atopic dermatitis, urticaria and anaphylaxis. The cell was described by Paul Erlich in 1878 [1], but had already been linked to allergies some years earlier [2]. It is not until recent decades, however, that the evolution of the cell has been described [3, 4] and its fascinating biology has only been depicted within recent years [5, 6]. We here give a review on systemic mastocytosis in regards to cell biology, diagnostic approaches and clinical management. METHODS A search was made in PubMed in August 2011 entering these keywords: mastocytosis, (systemic, cutaneous, aggressive), mast cell leukaemia, mast cell sarcoma, chromosome, mutation, haematology and treatment. A search for relevant reviews in the Cochrane Library revealed no relevant results. The mast cell The mast cell originates from the pluripotent “cluster of differentiation” (CD)-34-positive haematopoietic stem cell [7]. Mast cell progenitors are known to leave the bone marrow before complete maturation and to “home” for well-vascularized tissues. In contrast, all other myeloid cells reside in the bone marrow until they have achieved complete maturation [8, 9]. Murine models have led to the identification of distinct mast cell progenitors and, furthermore, shown that these progeni- tors originate from pluripotent stem cells [10]. Other studies have shown that mast cells and basophil granu- locytes are derived from a common progenitor cell which is differentiated after the granulocyte-monocyte progenitor-stage [3]. It is possible that the order of expression of certain transcription factors, especially Systemic mastocytosis – a systematic review Christen Lykkegaard Andersen 1, 6 , Thomas Kielsgaard Kristensen 2 , Marianne Tang Severinsen 3 , Michael Boe Møller 2 , Hanne Vestergaard 4 , Olav J. Bergmann 5 , Hans Carl Hasselbalch 1 & Ole Weis Bjerrum 6 SYSTEMATIC REVIEW 1) Department of Haematology, Roskilde Hospital 2) Department of Clinical Pathology, Odense University Hospital 3) Department of Haematology, Aarhus University Hospital, Aalborg Hospital 4) Department of Haematology, Odense University Hospital 5) Department of Haematology and Infectious Diseases, Esbjerg Hospital 6) Department of Haematology, Rigshospitalet Dan Med J 2012;59(3):A4397 ABBREVIATIONS AHNMD = associated non-mast cell lineage clonal haematological malignancy/disorder AML = acute myelogenous leukaemia ANC = absolute neutrophil count ASM = aggressive systemic mastocytosis CD = cluster of differentiation GI = gastrointestinal ISM = indolent systemic mastocytosis MCL = mast cell leukaemia MCS = mast cell sarcoma MDS = myelodysplastic syndrome MPN = myeloproliferative neoplasia PDGFRA = platelet-derived-growth-factor-alpha SM = systemic mastocytosis SM-AHNMD = systemic mastocytosis with associated clonal haematological non-mast cell lineage disease WHO = World Health Organization