Ann Thorac Surg 2012;93:e9-e10. doi:10.1016/j.athoracsur.2011.07.093
© 2012 The Society of Thoracic Surgeons
Case Reports
Anterior Mediastinal Mass Secondary to Histoplasmosis
David D. Shersher, MDa,
Edward Hong, MDb,
John Breard, MDb,
William H. Warren, MDb,
Michael J. Liptay, MDb,*
a Department of General Surgery, Rush University Medical Center, Chicago, Illinois
b Department of Thoracic Surgery, Rush University Medical Center, Chicago, Illinois
Accepted for publication July 28, 2011.
* Address correspondence to Dr Liptay, Division of Thoracic Surgery, Rush University Medical Center, 1725 W Harrison St, Ste 774, Chicago, IL 60612-3824 (Email: michael_liptay{at}rush.edu).
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Abstract
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Histoplasmosis in the mediastinum is an uncommon diagnosis that presents similarly to other benign and neoplastic conditions encountered in the chest. Here we describe a 36-year-old woman who presented with dyspnea secondary to a large anterior mediastinal mass that was biopsy and culture negative for neoplasm or infection. Video-assisted thoracoscopic surgery biopsy confirmed a large anterior mediastinal mass adherent to the aorta, which contained foci of histoplasmosis species. She is currently undergoing a long postoperative course of itraconozole and an empiric course of oral steroids to prevent development of fibrosing mediastinitis.
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Introduction
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Primary mediastinal masses comprise a diverse group of benign and neoplastic conditions that are frequently addressed by a chest surgeon. In an excellent review of mediastinal masses, Strollo et al [1] divide the mediastinum into anterior, middle and posterior compartments based on the Fraser classification. The differential diagnosis of an anterior mediastinal mass, which we describe herein, includes thymoma or thymolipoma, lymphangioma, lymphoma, thymic carcinoma or carcinoid, cyst, mediastinal germ cell tumor, goiter, and a misplaced parathyroid adenoma or carcinoma. Other benign differential diagnoses, which often masquerade as tumor, include tuberculosis and mycosis (most commonly histoplasmosis), sarcoidosis, Wegener's granulomatosis, systemic lupus erythematosus, and, rarely, Castleman's disease or inflammatory pseudotumor [2, 3].
Here we describe an uncommon case of a 36-year-old woman with no known past medical or significant exposure history who presented with dyspnea secondary to a large anterior mediastinal mass that was biopsy and culture negative for neoplasm or infection. She subsequently underwent video-assisted thoracoscopic surgery (VATS) biopsy that confirmed a large mass unresectable from the aorta due to adherence, which contained foci of histoplasmosis species by periodic acid–Schiff (PAS) and Grocott's methenamine silver (GMS) stains. Here we illustrate her clinical course and discuss the diagnostic and therapeutic recommendations for mediastinal histoplasmosis.
The patient was a 36-year-old woman with no significant past medical or exposure history who presented to the medical center with complaints of dyspnea for 1 year and chest pain for 1 week. She had a negative cardiac workup and a chest radiograph that demonstrated left hilar lymphadenopathy that was confirmed with chest computed tomography (CT) to be a 3.1 x 2.9 x 4.3 cm heterogeneously enhancing, noncavitary mass of the left anterior mediastinum with extrinsic compression on the main pulmonary artery (
Fig 1
). The patient underwent a CT-guided biopsy that was negative for infection or neoplasm. Infectious workup included a negative serum and urine screen for histoplasma. One month after discharge, the patient returned to the medical center with worsening dyspnea, where she underwent a negative flexible bronchoscopy and a left video-assisted thoracoscopy with pericardial window for evacuation of an iatrogenic hemopericardium and a thoracoscopic biopsy of the large anterior mediastinal mass. Incision into the mass revealed a necrotic core consistent with infectious etiology, corroborated by negative cytopathologic evaluation for malignancy (
Fig 2A). Due to the fibrotic nature of the mass and its adherence to the aorta, it was impossible to excise the lesion entirely and the case was deferred to medical management. Final pathology confirmed necrotizing lymphadenitis containing fungal forms on PAS and GMS stains (
Fig 2B) that were consistent with histoplasmosis. The patient was discharged from the hospital in stable condition and is currently undergoing long-term treatment with itraconazole and empiric oral steroid to prevent fibrosing mediastinitis.
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Fig 1. Preoperative computed tomography demonstrating a heterogeneously enhancing left anterior mediastinal mass (3.1 x 2.9 x 4.3 cm) at the level of the aortopulmonary window, causing mass effect on the main pulmonary artery. (A) Axial, (B) sagittal, and (C) coronal views are demonstrated.
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Fig 2. (A) Intraoperative thoracoscopic post biopsy view of the lesion's necrotic, purulent core with associated anthracotic lymph nodes. (B) A Grocott's methenamine silver (GMS) stained photomicrograph depiction of the biopsied mass, with dark lesions representing fungal elements. (Magnification, 200 x.)
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Comment
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Histoplasmosis in the mediastinum is an uncommon diagnosis, although it is the most common mycosis that presents in the chest (followed in frequency by Coccidoides immitis, Cryptococcus neoformans, and Blastomyces dermatidis) [2]. Histoplasma capsulatum is endemic to the eastern and central river valleys of the United States. Dines and colleagues[4] estimate that 80% of the US population is sensitized to the fungus and 22% are infected by it. Although the majority of those infected never exhibit active disease, early diagnosis of symptomatic histoplasmosis is critical to prevent the systemic complications of fungemia and the local debilitating complication of fibrosing mediastinitis.
Diagnosis and treatment, however, are not always straightforward. A retrospective 15-year Mayo institutional review by Assi and coworkers[5] evaluated 111 patients with known systemic histoplasmosis between 1991 and 2005. Notable to this large group of patients, 25% had negative serology and 20% had negative urine antigen screen tests [5]. Those patients not definitively diagnosed by serology or urine screen require biopsy. After diagnostic biopsy, surgical treatment of large histoplasma granulomas of the mediastinum consists of excision (irrespective of symptom), followed by long term anti-fungal treatment with amphotericin B or itraconazole [6]. Some groups also advocate empiric treatment with oral steroids in order to prevent the dreaded complication of fibrosing mediastinitis.
Several entities in the chest appear clinically similar to histoplasmosis. Case studies in pediatric patients report the difficulty of differentiating thoracic lymphoma from histoplasmosis due to the often insidious nature of both conditions [7]. Frey and associates [8] also describe a separate diagnostic entity of inflammatory pseudotumor of the lung. This rare fibrotic and reactive condition (usually after documented infection) pathologically contains fibrous hyalinized bands of tissue, lymphocytes, histiocytes, and polyclonal plasma cells [3]. Mediastinal histoplasmosis has a similar pathologic description and can sometimes be even found within a focus of inflammatory pseudotumor by identification of fungal elements [8]. Unlike in lymphoma, where treatment algorithms often exclude surgical intervention, treatment of mediastinal histoplasmosis and inflammatory pseudotumor is similar—surgical resection for a mediastinal granulomatous mass to prevent fibrosing mediastinitis or abscess formation and antimycotic or antibacterial treatment if presence of pathogen is confirmed on culture or stain.
Mediastinal histoplasmosis is indeed an uncommonly reported condition and, if suspected, should be included in the differential diagnosis of a mediastinal mass even in the context of negative cultures or antigen studies.
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References
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- Strollo DC, Rosado de Christenson ML, Jett JR. Primary mediastinal tumors. Part 1: tumors of the anterior mediastinum. Chest 1997;112:511-522.[Medline]
- Shields TW, Locicero J, Reed CE, Feins RH. General Thoracic SurgeryPhiladelphia: Lippincott Williams & Wilkins; 2009.
- Narla LD, Newman B, Spottswood SS, Narla S, Kolli R. Inflammatory pseudotumor Radiographics 2003;23:719-729.[Abstract/Free Full Text]
- Dines DE, Payne WS, Bernatz PE, Pairolero PC. Mediastinal granuloma and fibrosing mediastinitis Chest 1979;75:320-324.[Medline]
- Assi MA, Sandid MS, Baddour LM, Roberts GD, Walker RC. Systemic histoplasmosis: a 15-year retrospective institutional review of 111 patients Medicine (Baltimore) 2007;86:162-169.[Medline]
- Mathisen DJ, Grillo HC. Clinical manifestation of mediastinal fibrosis and histoplasmosis Ann Thorac Surg 1992;54:1053-1057discussion 1057–8.[Abstract/Free Full Text]
- Gaebler JW, Kleiman MB, Cohen M, et al. Differentiation of lymphoma from histoplasmosis in children with mediastinal masses J Pediatr 1984;104:706-709.[Medline]
- Frey A, Eichfeld U, Schubert S, Friedrich T, Schonfelder M. Inflammatory pseudotumor of the lung in hilus lymph node histoplasmosis Chirurge 1998;69:1101-1104.
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Abstract
Introduction
