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Journal of Cancer Research and Therapeutics, Vol. 7, No. 3, July-September, 2011, pp. 340-343 Letter to the Editor - Documenting a Case Fluoro-deoxy glucose-avid endobronchial inflammatory myofibroblastic tumor mimicking bronchial malignancy: Report of a case Sumeet G Dua1, Nilendu Purandare1, CS Pramesh2, George Karimundackal2, Santosh Menon3, Sneha Shah1, V Rangarajan1 1 Bio-Imaging Unit, Division of Thoracic Surgery, Tata Memorial Hospital, Mumbai, India PMID: 22044819 DOI: 10.4103/0973-1482.87001 Pulmonary inflammatory myofibroblastic tumor (IMT) is a well recognized mimic of lung cancer and is known to misguide radiological interpretation, pathological analysis, and clinical management. The attributes of pulmonary IMTs on routine cross-sectional imaging though described are non-specific. Also, the current understanding of the characteristics of IMTs on positron emission tomography/computed tomography (PET/CT) is anecdotal and is in the nascent stages. We describe the rare occurrence of an IMT in an endobronchial location; the diagnosis of which was made following bronchoscopic excision for a suspected localized airway cancer on the basis of its clinical presentation and PET/CT findings. A 62-year-old woman presented with a two month history of intermittent cough and dyspnea with occasional wheezing and streaky hemoptysis. She was a non-smoker and her occupational and family history was non-contributory. Systemic examination revealed mild expiratory wheeze with reduced breath sounds over the entire left hemithorax. A preliminary chest radiograph was suggestive of left-sided volume loss with ipsilateral shift of mediastinum. To characterize the radiographic findings, a CT study was requested which revealed complete collapse of the left lung with associated ipsilateral mediastinal shift. No hilar mass or adenopathy was noted; however, a 2 cm endoluminal growth was seen in the left main bronchus [Figure - 1]a causing its abrupt termination about 1 cm from the carina with associated collapse of the entire left lung. No hilar invasion or extra-bronchial spread was noted. The contralateral aerated lung did not show any nodules. Fiber optic bronchoscopy showed a large fleshy growth in the left main bronchus, 1 cm from the carina, occluding the entire bronchial lumen. Biopsy, bronchial washings, and post-bronchoscopy sputum cytology were all negative for malignancy and showed only inflammatory cells with occasional atypical squamous cells. A staging PET/CT study showed abnormal intense flouro-deoxy glucose (FDG) uptake (maximum standardized uptake value 16.4) in the growth [Figure - 1]a and b. No morphological or metabolic abnormality was noted in the liver, adrenal or elsewhere to suggest metastatic involvement. Since fiber-optic bronchoscopic biopsy was inconclusive and there was no parenchymal mass to enable a CT-guided biopsy, a rigid bronchoscopy was planned to achieve histopathological diagnosis. On rigid-bronchoscopy, a pedunculated fleshy mass was seen in the left main bronchus which was completely excised from its base and sent for histopathological examination. Histopathology of the excised growth, however, did not show any evidence of malignancy; instead metaplastic squamous epithelium with spindle cell proliferation underneath and sprinkled inflammatory cells was seen [Figure - 2]. The cells were positive for smooth muscle actin (SMA) and calponin and negative for cluster of differentiation (CD) 10, Alk-1, CK, and p53. The final histopathological diagnosis was inflammatory myofibroblastic tumor. The patient had an uneventful post-operative recovery. She received systemic steroids in the post operative period and serial radiographs showed progressive reduction in atelectatic opacification. She is currently asymptomatic and is on regular follow-up. Inflammatory myofibroblastic tumor is a well recognized, albeit infrequently seen neoplasm, notorious for its variable clinicoradiological characteristics and pathological features. Also known as plasma cell granuloma, inflammatory fibrosarcoma, fibrous histiocytoma, and inflammatory fibromyxoid tumor, [1] IMTs have a predilection for the chest and are the commonest primary pulmonary tumor in children under 16 years of age, [2] though unusually IMTs may even involve the heart. [3] Typically, pulmonary IMTs are parenchymal tumors seen in children and young adults with a peak incidence in the 2 nd decade. Non-specific symptoms like cough, fever, dyspnea, chest pain, hemoptysis, or wheezing may be seen at presentation, although about 40% of the patients are reportedly asymptomatic. [4] On chest radiography, pulmonary IMTs appear as a solitary, peripherally located, well-demarcated nodule or mass, with a predilection for the lower lobes. In addition to the above features, IMTs show heterogeneous attenuation on CT, and appear isointense and hyperintense to muscle on T1 weighted and T2 weighted magnetic resonance images, respectively. Infrequently, IMTs may show extraparenchymal extension to involve the mediastinal or hilar structures. Calcification may also be noted within the tumor; although cavitation and lymphadenopathy are rare. [4] The imaging attributes are however non specific and IMTs can mimic lung cancers. The diagnostic dilemma is further compounded when IMTs occur in elderly patients or at unusual locations (endobronchial), as seen in our case. Our patient was a sexagenarian with a tumor that was confined to the bronchial lumen, and thus our initial suspicion was of a malignancy; the commonest tracheobronchial tumor in the adult population. [5] The increased uptake of FDG seen on the staging PET/CT study further strengthened our clinicoradiological suspicion. The differentials considered were the commonest squamous cell carincoma or other infrequently seen tumors, such as adenoid cystic carcinoma, mucoepidermoid carcinoma, carcinoid, and metastases. However, the imaging appearance of the above mentioned neoplasms and few rare benign tumors like the IMT can overlap on CT and PET, i.e. endobronchial mass with high FDG uptake. Thus, the final diagnosis of IMT could only be made on pathological examination of the excised specimen. On histopathology, IMTs are composed of myofibroblastic spindle cells with an accompanying inflammatory infiltrate of plasma cells, lymphocytes, and eosinophils. [1] The spindle cells stain positive for vimentin and actin and these tumors often show clonal cytogenetic abnormalities involving 2p23 locus that encodes ALK gene. [6] The abundance of inflammatory cells within the inflammatory pseudotumors is responsible for increased FDG accumulation in the tumor. The high FDG uptake in IMTs makes it difficult to differentiate them from malignant tumors and is known to be a cause of false positive PET scans. [7] Two such recent anecdotes [8],[9] of FDG positive endobronchial IMTs have been reported where PET studies were performed to stage suspected malignancies and the diagnosis of IMT was established after lobectomy. The treatment of choice for pulmonary IMTs is surgical excision. Wedge resection is the preferred procedure and more radical surgeries, such as lobectomy and pneumonectomy, are generally undertaken when the former is not possible. [8] On the other hand, there is no consensus on the management of endobronchial IMTs owing to their rarity, though various case-based approaches ranging from conservative to radical has recently been suggested. [10] While favorable outcomes have been reported with sleeve-resection and bronchoplasty, [11] recurrence following conservative surgeries can sometimes mandate radical bronchial resection with lobectomy. [12] It has been recently reported that tumors with no spread beyond the bronchial wall, as in our case, can be subjected to a trial of bronchoscopic resection [13] which is significantly less morbid than open surgical excision. In our patient, the pedunculated nature of the endobronchial tumor combined with a satisfactory bronchoscopic excision and a patient willing for regular follow-up and close surveillance prompted us to adopt a conservative approach. To summarize, this case demonstrates the rare occurrence of an endobronchial IMT in an elderly woman, the clinical presentation and the high FDG avidity of the lesion acting as confounding factors for the diagnosis of tracheobronchial malignancy. References
Copyright 2011 - Journal of Cancer Research and Therapeutics The following images related to this document are available:Photo images[cr11083f1.jpg] [cr11083f2.jpg] [cr11083f3.jpg] |
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