INFLAMMATORY MYOFIBROBLASTIC TUMOR OF PLEURA: A RARE BENIGN TUMOR

Abstract

SESSION TITLE: Fellows Disorders of the Pleura Posters SESSION TYPE: Fellow Case Report Posters PRESENTED ON: October 18-21, 2020 INTRODUCTION: Inflammatory myofibroblastic tumor (also known as plasma cell granuloma, inflammatory pseudotumor, fibrous histiocytoma, fibroxanthoma, xanthogranuloma) is a rare benign neoplasm which can also be locally invasive. The symptoms and radiological findings are mostly non-specific. It is occasionally reported in lungs with incidence of 0.04 - 0.7% of all lung tumors, whereas in pleura, it is rarely reported. CASE PRESENTATION: A 30yr female non-smoker presented with breathlessness, left sided chest pain for 2 months. CXR- large homogenous opacity in the left hemithorax sparing the left upper zone. HRCT chest - a large multiloculated, multiseptated cystic lesion was found in left pleural cavity with collapse of underlying left lung and mild pleural effusion. Thoracotomy was performed and a large fleshy highly vascular mass was noted of size 30cm x 20cm having variegated margins, adherent to lower lobe of left lung, diaphragm and postero-medial aspect of mediastinum. The tumor was resected in-toto weighing around 4.5kg. HPE of the tissue showed features of INFLAMMATORY MYOFIBROBLASTIC TUMOR. IHC analysis showed positive staining for vimentin and smooth muscle actin(SMA) confirming the diagnosis DISCUSSION: IMT was first described in lungs by Brunn in 1939. It is reported in other extrapulmonary sites like orbit, liver, spleen, thyroid, breast, lymph nodes, skull base and rarely in pleura. Pathogenesis of IMT is still unknown. One Hypothesis is that, IMTs are low grade mesenchymal neoplasms with a secondary inflammatory component. It is supported by the presence of a fusion gene ALK gene, a tyrosine kinase oncogene located on chromosome 2p23, initially found to be arranged in anaplastic large cell lymphomas, leading to overexpression of ALK gene. The cytoplasmic expression of ALK gene is found on immunohistochemistry in some cases of IMT. It is found less commonly in pulmonary IMT than in extrapulmonary IMT. The clinical findings and symptoms are largely non-specific. The symptoms may be cough, dyspnea, chest pain, hemoptysis, fever and fatigue. Weight loss and anorexia are rare. Approximately 70 percent of patients are asymptomatic and tumor discovered incidentally on chest x-ray. Approximately 50 percent of the patients have an elevated sedimentation rate, mild anemia and thrombocytosis can also occur. The diagnosis of IMT requires the presence of characteristic pathological features- a background proliferation of spindle cells associated with a variable dense polymorphic infiltrate of mononuclear inflammatory cells CONCLUSIONS: IMT is a rare benign tumor. Clinical and radiological presentation is variable and nonspecific and diagnosis can be made only by histopathological and immunohistochemical studies. Despite being benign, its potential for recurrence and local invasion requires complete surgical resection. 4.5 kg of IMT pleura was never reported in literature till now. Reference #1: R. J. Cerfolio, M. S. Allen, A. G. Nascimento et al., “Inflammatory pseudotumors of the lung,” Annals of Thoracic Surgery, vol. 67, no. 4, pp. 933–936, 1999. Reference #2: J. Loeffler-Ragg, J. Bodner, M. Freund et al., “Diagnostic and therapeutic challenges of a large pleural inflammatory myofibroblastic tumor,” Case Reports in Pulmonology, vol. 2012, Article ID 102196, 5 pages, 2012. Reference #3: C. M. Coffin, A. Patel, S. Perkins, K. S. J. Elenitoba-Johnson, E. Perlman, and C. A. Griffin, “ALK1 and p80 expression and chromosomal rearrangements involving 2p23 in inflammatory myofibroblastic tumor,” Modern Pathology, vol. 14, no. 6, pp. 569–576, 2001. DISCLOSURES: No relevant relationships by PRAPULLA CHANDRA DAVULURI, source=Web Response