Inflammatory Myofibroblastic Tumor (IMT): A Rare and Puzzling Entity

Abstract SESSION TYPE: Cancer Case Report Posters IPRESENTED ON: Tuesday, October 23, 2012 at 01:30 PM - 02:30 PMINTRODUCTION: IMT is a distinctive mesenchymal neoplasm of the lung of uncommon occurrence.CASE PRESENTATION: A 36 year old African American female presented with subacute right anterior chest pain, productive cough, and 30 pound weight loss. Chest radiograph (CXR) and Computed tomography (CT) of the chest with contrast showed right upper lobe (RUL) infiltrate. CT chest ruled out pulmonary embolism. A course of antibiotics followed with no improvement in either symptoms or radiographic findings. She underwent flexible bronchoscopy which was non-diagnostic. It was followed by a CT guided biopsy of the RUL infiltrate which revealed predominantly a mixture of plasma cells and lymphocytes. She underwent a Video Assisted Thoracoscopic biopsy which confirmed diagnosis of IMT of the Lung(Image 2). Anaplastic Lymphoma Kinase (ALK-1) stain was negative and IgG subclass IV was normal. Positive Emission Tomography revealed four hypermetabolic nodules in the RUL, one of them close to the right hilum. Patient is scheduled for RUL and middle lobe resection.DISCUSSION: IMT is a benign or low-grade neoplasm (1)(2). Lung involvement is seen in about one-third of the cases(1). Incidence is between 0.04 to 1.2% of all resected lung tumors(1).There is no gender or racial predilection (1)(3). Patients may be asymptomatic with an incidental nodule on CXR or symptomatic with fever, cough, chest pain, or hemoptysis (2). CT Chest usually shows nonspecific nodule or enlarging lung mass which may have well defined or irregular margins (2).There is an anatomic bias for lower lobes(3). Multiple nodules are seen in only 5% of cases (3) and hence the presentation of our case is relatively uncommon. Differential diagnosis include primary or metastatic neoplasm, benign tumors like chondroma and hamartoma(3). IMTs are characterized by cellular spindle cell proliferation in a myxoid to collagenous stroma with a inflammatory infiltrate composed of predominantly plasma cells and lymphocytes(2). ALK positivity is seen in approximately 50% of cases(2). They are variably positive for Actin, Desmin, Calponin, Keratin and hence not diagnostic(2). Histological features do not correlate with clinical behavior(2). They have a tendency for local recurrence and a small risk of distant metastasis(1). Complete surgical resection gives an excellent prognosis(2). The possibility of recurrence after several years mandates prolonged follow up(2). ALK positive tumors may show partial response to Crizotinib an oral competitive inhibitor of the ALK which has been used with partial success.CONCLUSIONS: IMT is a rare mesenchymal neoplasm of intermediate biological potential which unlike aggressive malignant tumors have a good potential for cure.1) Takeda et al.Interactive CardioVascular and Thoracic Surgery 7 (2008) 629-6332) Gleason et al.Inflammatory myofibroblastic tumours:where are we now?J Clin Pathol 2008;61:428-4373) Agrons et al.Pulmonary inflammatory pseudotumor:Radiologic features.Radiology 1998; 206: 511-18DISCLOSURE: The following authors have nothing to disclose: Nitesh Jain, Aman Sethi, Hasnain Bawaadam, Nisha Jain, Puja Sethi, Fazila Barodawala, Fauzia Wani, Kovid Trivedi, Anjali Shinde, Sivashankar SivaramanNo Product/Research Disclosure InformationChicago Medical School/Rosalind Franklin University of Health a Science, North Chicago, IL.