Kuppe et al. Allergy, Asthma & Clinical Immunology 2012, 8:6 http://www.aacijournal.com/content/8/1/6 C A S E R E P O R T ALLERGY, ASTHMA & CLINICAL IMMUNOLOGY Open Access Macrophage activation syndrome in a patient with pulmonary inflammatory myofibroblastic tumour Christoph Kuppe1*, Saskia Westphal2, Eva Bücher1, Marcus J Moeller1, Bernhard Heintz1, Marion E Schneider3 and Jürgen Floege1 Abstract We describe for the first time a case of macrophage activation syndrome (MAS) in a patient with a history of inflammatory myofibroblastic tumour (inflammatory pseudotumour, IPT) of the lung and thoracic spine. The patient was admitted to the intensive care unit with a history of prolonged remitting fever, hepatosplenomegaly, bilaterally enlarged thoracic lymph nodes and an acute severe inflammatory response syndrome (SIRS). Up-regulated cytokine production (e.g. IL-1ß and IL-6), increased levels of ferritin and circulating soluble interleukin-2 receptor (sIL-2R, sCD25) led to the differential diagnosis of MAS. Bone marrow aspiration, the main tool for a definite diagnosis, revealed macrophages phagocytosing haematopoietic cells. Immunosuppressive therapy with corticosteroids and cyclosporine was an effective treatment in this patient. Keywords: Macrophage activation syndrome, Haemophagocytosis, Pulmonary plasma cell granuloma Introduction Macrophage activation syndrome (MAS) is a rare but po- tentially fatal disorder, characterized by combinations of pancytopoenia, liver failure, coagulopathy and organ dys- function. It is thought to be caused by the activation and uncontrolled proliferation of CD8+ lymphocytes and well- differentiated macrophages, leading to haemophagocytosis and a so-called cytokine storm [1-3]. The term MAS describes a condition occurring in a broad spectrum of diseases, which belong to the histiocytic disorders, e.g. haemophagocytic lymphohistiocytosis (HLH). Familial or primary haemophagocytic lymphohistiocytosis has a known and well-characterized genetic basis, namely a mu- tation in the perforin gene [4]. It results in the inability of cytotoxic T lymphocytes (CTLs) or natural killer (NK) cells to lyse target cells. Secondary HLH can be found in patients with infections, malignancies and inflammatory diseases such as juvenile idiopathic arthritis (JIA) or it may be an adverse effect of certain drugs [5]. * Correspondence: ckuppe@ukaachen.de 1Department of Nephrology and Clinical Immunology, University Hospital of the Aachen University of Technology (RWTH), Aachen, Germany Full list of author information is available at the end of the article Inflammatory myofibroblastic tumours are rare tumours with different invasive tendencies and growth capacity [6]. In fact, this tumour entity represents the non-neoplastic unregulated growth of inflammatory cells and fibroblasts or myofibroblasts, irrespective of their organs of origin [7]. Pulmonary inflammatory myofibroblastic tumours usually consist of a mixed inflammatory infiltrate with a predominance of plasma cells [8]. Two theories exist concerning the origin of IPTs. According to one the- ory, the tumour is in fact a regular inflammatory process, which follows interstitial pneumonia. Subse- quently, it transforms into an organized pneumonia and, eventually, into an inflammatory myofibroblastic tumour. In support of this hypothesis, production of IL-6 mRNA and protein by tumour cells in IPT has been reported in some cases [8,9]. Yet, according to another hypothesis, some plasma cell granulomas rep- resent slow-growing mesenchymal tumours with sec- ondary inflammatory changes. In this report, we describe for the first time the oc- currence of MAS in a patient with a history of an in- flammatory myofibroblastic tumour of the lung and thoracic spine. © 2012 Kuppe et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.