Case presentation: A 17-year-old girl who suffered from a dry cough with right chest pain. Contrast-enhanced CT showed a huge heterogeneous mass with calcified plaques. A surgical management strategy was successfully undertaken. Increasing physician awareness of this entity should facilitate recognition of its clinical characteristics and laboratory findings.
Conclusions: This case suggests that a rarely huge and surgically treated IMT in a teenager and concerned with the radioclinical, histopathological, therapeutic aspects of this disease.
Inflammatory myofibroblastic tumor, Lung, Surgery
Inflammatory myofibroblastic tumor (IMT) is a rare benign tumor that often affects children. It has been first described by Brunn in 1939  and it accounts for 0.71% of all lung tumors. [2, 3]. The origin of the IMT is unknown, but recent studies have shown that it is a true tumor rather than a reaction process . Different terms used to describe IMT include inflammatory pseudotumor, cellular inflammatory pseudotumor, plasma cell granuloma and inflammatory fibrosarcoma. This lesion consists of inflammatory cells and myofibroblastic spindle cells [5, 6]. We report a case with a rarely huge and surgically treated IMT in a teenager and concerned with the radioclinical, histopathological, therapeutic aspects of this disease.
A 17-year-old girl was referred to our hospital with a 15 days history of right chest and cough without sputum. She denied the following symptoms including the presence ofhoarseness, hemoptysis, anddyspnea. Her medical history and family history were uneventful. Physical examination revealed normal breath sounds in both of the lung fields. The results of laboratory examinations, including arterial blood gases, hematology tests and biochemistry tests, were within normal limits. Her Pulmonary function tests and cardiovascular examination revealed normal performance. Contrast-enhanced chest computed tomography (CT) showed an 18×16×15 cm heterogeneous mass with calcified plaques invading the entire right hemithorax and mediastinal shift to the left (Fig 1A, 1B). However, the patient refused to have the bronchoscopic examination and fine-needle biopsy of the mass. As diagnosis was not established through imaging, surgery was scheduled. Under general anesthesia with selective intubation, a huge mass (measuring 20×17×17 cm and weighing 2010g) with inferior vena cava and right pericardium invasion was found and the right middle and lower lobes bronchus appeared encased by the mass. At last, the neoplasm was completely excised. The patient underwent a right middle and lower lobectomy, inferior vena cava angioplasty and partial resection of pericardium. Mediastinal lymph node dissection was also accomplished. The feeding vessels of the mass were ligated and the mass was removed without tumor spillage or capsular injury. After that, reexpansion of the right upper lobe was observed and a chest tube was placed to drain the pleural cavity. A postoperative roentgenogram of the chest showed that the mediastinum had returned to its normal position and the right lung was well expanded. Microscopic examination revealed a proliferation of regular spindle cells arrayed in fascicles, admixed with lymphocytes, plasma cells and eosinophils. Additional immunohistochemistry with anaplastic lymphoma kinase (ALK)-1 and smooth muscle actin (SMA) revealed positive and the translocation of the ALK gene was found by fluorescence in situ hybridisation (FISH). The results for desmin, S-100, CD99, CD34, Myogenin, EMA and pankeratin were negative. Ki-67 proliferative activity was 8%. Based on these data, the diagnosis of inflammatory myofibroblastic tumor was retained. Histologic diagnosis showed a negative bronchial margin and lymph nodes free of malignancy. The patient made an uneventful postoperative recovery and was followed up for two months without evidence of recurrence to date.
Inflammatory myofibroblastic tumor (IMT) is a rare massforming lesion characterized by fibroblastic or myofibroblastic spindle cell proliferation with varying degrees of inflammatory cell infiltration. The World Health Organization (WHO) classified IMT as a distinct entity in 1994 . However, the huge inflammatory myofibroblastic tumor of chest is even rarely observed and there is few literatures described the disease (Table). The cause of IMT tumors is unclear, but an immunological response to an infectious agent or noninfectious agent remains possible . Whereas some reporters demonstrated that IMT tumors are true neoplasms and some believe the IMT tumors to be a low-grade sarcoma with inflammatory cells as it has a potential for local recurrence, infiltration, multicentricity, and rarely metastases . Also, ALK positivity is detected in 36% to 60% of cases and the presence of chromosomal aberrations in these tumors suggests that IMT is a neoplastic proliferation of clonal origin . In our case, there was no evidence of infection or inflammatory response and no history of trauma in her chest. The tumor was single and circumscribed, and movable.
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The IMT affects both sexes, at any ages, with a slight predominance in children and young adults [4, 11]. Most patients are asymptomatic and the tumor is discovered incidentally on a chest X-ray performed for another reason [4, 11].From the table, all of the four patients were young adults and were referred to the hospital with a common symptom of cough. In our patient, the tumor was discovered at an early age and the only symptoms were dry cough and right chest pain.
Radiological aspects are capricious. Chest radiographs are the most generally performed imaging study to evaluate the neoplasm. Most patients have a mass or a pulmonary nodule, generally measuring 1 to 6 cm in diameter . On CT scans, these tumors shows typically heterogenous attenuating enhancement . Sometimes the tumor can extend towards the hilum, mediastinum, pleura or diaphragm [1, 3]. As recorded in the table, all the sizes of masses were huge and two of them were observed the invasion of the mediastinal or the chest wall. There is also a word of caution in our case that the representative calcifications were observed in the centure of heterogeneous mass and it invaded the inferior vena cava and right pericardium.
Microscopically the IMT tumor consists of spindle shaped cells that are mixed with a chronic inflammatory component that consists of plasma cells, lymphocytes, and occasional histiocytes. Immunohistochemistry for ALK discovered cytogenetic abnormalities on chromosome 2p23 is relatively specific for IMF tumor among the spectrum of fibroblastic-myofibroblastic tumors and other potential mesenchymal mimics of IMF tumor . The recent WHO classification of soft tissue tumors recognizes 3 basic variants of IMT: (1) loosely organized myofibroblasts in an edematous myxoid background with plasma cells, lymphocytes, eosinophils, and blood vessels, resembling nodular fasciitis; (2) dense aggregates of spindle cells arrayed in a variable myxoid and collagenized background and admixed with a distinctive inflammatory infiltrate, diffuse clusters of plasma cells, and lymphoid nodules, resembling fibrous histiocytoma or fibromatosis; and (3) collagen sheets with scattered plasma cells and eosinophils resembling a scar or desmoid tumor .
The differential diagnosis of IMT is follicular dendritic cell tumor and inflammatory pseudotumor. Follicular dendritic cell sarcoma (FDCS), which was first reported by Monda et al. in 1986, is a rare neoplastic proliferation that exhibits the morphological and immunophenotypic features of FDCS that are among the accessory cells of the lymphoid system. The tumor cells exhibited positive immunohistochemical staining for vimentin, CD21 and CD35 as well as negative staining for ALK-1 and SMA. Inflammatory pseudotumors are benign tumors commonly found in the lung and they are characterized by proliferation of spindle cells (fibroblasts and myoblasts), with variable numbers of mitoses, and inflammatory cells infiltration, particularly plasma cells. More recently, the presence of anaplastic lymphoma kinase (ALK 1) staining in some cases has been postulated to be of value in the confirmation of IMT and in its distinction from other entities. A series of studies found the translocation of the ALK gene by fluorescence in situ hybridisation (FISH) in IMT (16). In our case, the mass was spindle cell lesion with severe atypism and some mitosis. As shown in Fig 2 (A, B, C), ganglion-like cells were present and the immunohistochemistry result for ALK-1 shows strong positivity of tumor cytoplasm and translocation of the ALK gene. Based on these findings, her tumor may be very aggressive.
Despite IMT is a benign tumor, it is considered by some authors as a low grade tumor because of malignant features such as local invasiveness, recurrence or malignant transformation. Complete surgical resection is the appropriate treatment for IMT. Cerfolio and colleagues reported an excellent prognosis in patients undergoing complete resection of pulmonary IMT, with a 5-year survival rate of 91.3%. However, a 60% recurrence rate in those receiving incomplete resection has been reported in the same study . Corticosteroid monotherapy may result in rapid resolution of the disease and sustained remission (17, 18). Non-steroidal anti-inflammatory agents (NSAIDs) as solitary therapy may be extremely efficacious and anecdotal response to chemotherapy has also been reported (19). As the literature reviewed in the table, three patients had the operations by a standard posterolateral thoracotomy. Among them, two patients had the lobectomy and the other had the complete resection with two through fourth ribs. The patient whose neoplasm invaded superior vena cava, heart atrium and right pulmonary vein underwent chemotherapy with bleomicin, etoposide and cisplatin. After two cycles of chemotherapy, the tumorslightly reduced in size and the patient only survived for 12 months.
In summary, inflammatory myofibroblastic tumor is a rare benign tumor. Because of its local invasiveness and its tendency to recur, IMT tumor can be confused with malignant lesions. Because the treatment of IMT tumor is conservative surgery, preoperative recognition is important to avoid radiation therapy, and intensive multi-agent chemotherapy that would be appropriate treatments for soft tissue sarcomas. Clinical and radiological presentation is variable and nonspecific and the diagnosis is rarely made before chirurgical management. Also, because the tumor with cellular atypia, ganglion-like cells, ALK and SMA reactivity has a more aggressive clinical behavior, a careful follow-up is required.
Figure 1: CT features of the case.
A and B: Contrast-enhanced CT showed a huge heterogeneous mass with calcified plaques.
B: Immunohistochemical staining showing strong reactivity for anaplastic lymphoma kinase (ALK)-1(X400)
C: Immunohistochemical staining showing strong reactivity for smooth muscle actin (SMA) (X400)