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  Table of Contents    
CASE REPORT  
Year : 2013  |  Volume : 56  |  Issue : 2  |  Page : 158-160
Mixed germ cell tumor of mediastinum/lung masquerading as hemangioma in fine needle biopsy


1 Texas Tech University Health Sciences Center - School of Medicine, Lubbock, USA
2 Department of Pathology, Covenant Hospital, Lubbock, USA

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Date of Web Publication23-Sep-2013
 

   Abstract 

The histological predominance of one component in a germ cell tumor can lead to a mistaken diagnosis. Here, we describe a mediastinal teratoma with predominant vascular proliferation (>90%) which on fine needle biopsy was diagnosed as a pulmonary hemangioma. Later, resection specimen revealed other components constituting ~4%, changing the diagnosis while illustrating theimportance of careful evaluation. A 37-year-old Caucasian male with shortness of breath, weight loss, and history of recently resolved pneumonia was diagnosed with hemangioma, after a computed tomography guided fine needle biopsy of a -16.3-cm mediastinal pulmonary mass revealed abundant benign vascular elements. Following tumor excision, ~94% of the sample exhibited predominant vascular elementsThe mass also exhibited rare focal areas of malignant epithelium in a reticular arrangement and undifferentiated pleomorphic cells associated with vascular invasion. These atypical epithelial cells were positive for CD30, pan CK, AFP, β-HCG and CD 117, thusprocuring a diagnosis of mediastinal mixed germ cell tumor. Although mixed germ cell tumors consist of various tissue types, diagnosis can be easily overlooked if one component dominates. Therefore, obtaining adequate representative neoplasm samples, and sectioning the samples thoroughly, searching for coexisting tissue types is critical for accurate diagnosis.

Keywords: Hemiangioma, mature teratoma, mediastinal, mixed germ cell tumor

How to cite this article:
Nuti R, Bodhireddy S, Thirumala S. Mixed germ cell tumor of mediastinum/lung masquerading as hemangioma in fine needle biopsy. Indian J Pathol Microbiol 2013;56:158-60

How to cite this URL:
Nuti R, Bodhireddy S, Thirumala S. Mixed germ cell tumor of mediastinum/lung masquerading as hemangioma in fine needle biopsy. Indian J Pathol Microbiol [serial online] 2013 [cited 2019 Sep 18];56:158-60. Available from: http://www.ijpmonline.org/text.asp?2013/56/2/158/118671



   Introduction Top


Germ cell tumors are generally classified based on their histology. Teratomas are made up of neoplastic germ cells that can differentiate along somatic cell lines. Of the three variants of teratomas [mature (benign), immature (malignant), and monodermal or highly specialized], mature teratomas consist of fully differentiated tissues from one or more germ cell layers, but in a haphazard arrangement. The most common type of mixed germ cell tumors demonstrates a combination of teratoma, embryonal carcinoma, and yolk sac tumor. [1] In this report, we describe how a mediastinal mixed germ cell tumor was initially mistaken and reported as hemangioma due to the fact that only a minute portion of the 16.3 cm mass lesion consisted of malignant elements.


   Case Report Top


A 37-year-old man with shortness of breath, weight loss, and history of recently resolved pneumonia was eventually diagnosed with a mediastinal mixed germ cell tumor. Based on clinical presentation and history, it was thought that the patient had a pneumonic patch. However, initial needle biopsies showed predominant mature teratoma with hemangioma-like components which favored the diagnosis of a mediastinal hemangioma. This was further supported by CT. Later on, histological sectioning of the excised specimen and immunochemistry indicated otherwise.

Radiologic findings

CT showed a 16.3 cm mass in the left chest that was centered immediately above the left hilum in the mid lung area [Figure 1]. There was good contrast opacification and the mass was clearly hypervascular in the arterial phase. The source of arterial blood supply was not identified and the mediastinal structures were shifted significantly to the right. A fine needle biopsy was performed.
Figure 1: CT scan of the chest showing a mediastinal mass with involvement of the left mid lung area

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Lung biopsy findings

The fine needle biopsy showed prominent vascular proliferation with variably thick walls and fragments of smooth muscle [Figure 2]. Morphologic features were suggestive of benign vascular proliferation, favoring a hemangioma. In view of the large size of the tumor, an excision was performed. Subsequent to the final diagnosis, radiation of the excision site was carried out.
Figure 2: Fine needle biopsy. Note prominent vascular proliferati on and bundles of smooth muscle (Hematoxylin and eosin stain, X10)

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Excised specimen findings

Tissue sections from the excised specimen demonstrated a mixed germ cell tumor with predominantly mature teratoma showing hemangioma-like elements, bronchial and squamous epithelium [Figure 3]. Focal areas demonstrated malignant epithelium [Figure 4], pleomorphic cells associated with vascular invasion suggestive of embryonal carcinoma, and small areas with reticular pattern compatible with yolk sac tumor.
Figure 3: Tissue secti on of excised specimen with hemangioma-like elements, and epithelial-lined spaces (Hematoxylin and eosin stain, ×20)

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Figure 4: Tissue secti on of excised specimen demonstrati ng malignant epithelium (Hematoxylin and eosin stain, ×10)

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Immunoperoxidase stainfindings

Stains for CD 30 and pan CK were positive within the malignant epithelium confirming the presence of embryonal carcinoma. A stain for alpha-fetoprotein and beta-hCG was positive in the reticular areas consistent with yolk sac tumor. A stain for CD 117 shows focal cytoplasmic staining within the malignant epithelium.


   Discussion Top


In general, mediastinal teratomas are uncommon, making up only about 5-10% of all mediastinal tumors. [2] The world-wide incidence of a teratoma is about 1 in 4000 live births. The most common sites for these tumors to occur are: Sacrococcygeal 40%, ovary 25%, testicle 12%, brain 5%, and others including neck and mediastinum 18%. [3] A mediastinal teratoma involving the lung is extremely rare. [4]

Teratomas are usually benign and are defined by the presence of at least two of the three embryonal germ layers: Endoderm, mesoderm, and ectoderm. [5] Histologically, the tumor from this patient contained all three layers, consistent with a teratoma. In fact, the most common mediastinal germ cell tumors are teratomas. In adults, germ cell tumors make up 10-20% of all anterior mediastinal masses. [5],[6] The vast majority of these tumors have well-defined, smooth or lobulated margins. [5] Approximately 80% of teratomas are of the mature type. [7] The mass found in this patient did not extend beyond the capsule and the margins were well-defined. Initially, mediastinal teratomas are asymptomatic and grow very slowly. In a few cases, these teratomas can become enormous and compress the adjacent trachea and bronchi, as in this patient. [6] Initially, the patient had come in for evaluation for pneumonia which led to the discovery of the mass. The size of the mass was small and deemed to be related to post-pneumonitic changes. Four years later, this mass had grown to be very large, shifting the mediastinal structures to the right and eliciting chest discomfort and cough.

Pulmonary involvement by tumor, although rare, requires specific evaluation in mediastinal teratomas. Like in a mediastinal teratoma, the common features are chest pain, fever, cough, bronchiectasis pneumonia, and weight loss, seen in about 53% of the cases. [4],[5] However, a pathognomonic symptom is trichoptysis and rarely hemoptysis, which our patient did not have. Most mediastinal teratomas with pulmonary involvement have a predilection for the left upper lobe. [4] Although our patient's tumor involved the left lung, it was in the mid lower lobe. Teratomas within the lung may also represent altered metastases from gonadal germ cell tumors such as seminoma, embryonal carcinoma, yolk sac carcinoma, and choriocarcinoma. [8] Our case demonstrated the presence of embryonal carcinoma and yolk sac tumor, although as minor components of the tumor. Yolk sac tumors may be rich in vascular, mesenchyme-like stroma which misled the interpretation as a hemangioma. Therefore, the presence of what seems to be a hemangiomatous lesion should serve as a warning of the possibility of a lurking germ cell component especially since in our case the radiologic differential pointed towards such a diagnosis. Further workup in such a case would help in the diagnosis process. In all cases of pulmonary teratomas, patients must be evaluated for gonadal germ cell tumors, to rule out metastases and establish a diagnosis of primary pulmonary or mediastinal teratoma, as was carried out in our case.

A mediastinal teratoma can be diagnosed by obtaining a complete and accurate history, physical examination, chest x-rays, and a chest computed tomography scan. A CT scan can accurately estimate the density of all included tissues. Magnetic resonance imaging can also prove to be a valuable in the detection of the anatomical relations of the mass to the mediastinal and the hilar structures. [6] For this patient, a chest x-ray was initially used which was misleading with respect to the patient's history of recovery from pneumonia. Later, a CT scan was used to identify the mass within the thoracic cavity. The subsequent CT-guided needle biopsy, excision and pathologic examination with immunohistochemistry finally established all the components of the tumor.

The radiologic differential diagnosis included: 1) benign mediastinal teratoma vs. malignant mediastinal teratoma, 2) hemangioma, 3) hamartoma, 4) intrapulmonary or mediastinal lipoma, and 5) germ cell tumor. The prognosis and the biologic behavior of teratomas depend on the presence or absence of immature tissue and the age of the patient. The patient in our case was an adult and the teratomatous portion of the mass demonstrated mature elements, both favorable prognostic features. It is uncommon for a mature teratoma to develop a focus of carcinoma, sarcoma, or be mixed with a malignant germ cell tumor. Mature teratomas can be completely resected, with low rates of recurrence. However, extensive histological examination of the excised specimen is required to determine possible presence of immature tissue, other germ cell components, carcinoma, or sarcoma. [5] In our patient, this proved to be valuable due to the identification of very small amounts embryonal carcinoma and yolk sac tumor.

Other rare differentials included a malignant mediastinal teratoma, which was ruled out by histological examination. [9] On the other hand, a hemangioma was a possibility since the fine needle biopsy showed a preponderance of benign vascular channels, although the excised specimen showed additional elements leading to the final diagnosis. Hamartoma is the most common benign lung tumor but presents generally in the sixth or seventh decades and is usually < 6 cm. Radiographically, an apparent calcific focus may be noted in these lesions. Finally, an intrapulmonary or mediastinal lipoma shows uniform fatty attenuation in the CT scan. Also, intrapulmonary lipomas tend to occur on the right and in middle-aged men. [5]

A thorough sampling of germ cell tumors is critical for accurate diagnosis and therefore prognosis and patient management. In the presence of an overwhelming dominance of a specific tissue type, a focal and small component of another specific germ cell type can be easily missed, particularly during initial diagnostic procedures yielding limited material. In young male patients with an intrathoracic mass lesion, a germ cell tumor must always be considered in the clinical, radiologic, and pathologic differential diagnosis. For the pathologist, even if initial biopsies reveal isolated components and may not be diagnostic, the possibility of a germ cell tumor must be raised in the report so that the clinician can manage the patient appropriately.

 
   References Top

1.Kumar V, Abul KA, Nelson F, Richard N. Robbins Basic Pathology. Philadelphia: Saunders. Elsevier. 2007.  Back to cited text no. 1
    
2.Allen MS. Presentation and management of benign mediastinal teratomas. Chest Surg Clin N Am 2002;12:659-64.  Back to cited text no. 2
[PUBMED]    
3.Anand S, Sheela L, Neeti A, Mahesh M, Ashwin A, Kiran P. Mature mediastinal teratoma: A rare cause of recurrent respiratory distress. People's J Sci Res 2010;3:33-5.  Back to cited text no. 3
    
4.Chen RF, Chang TH, Chang CC, Lee CN. Mediastinal teratoma with pulmonary involvement presenting as massive hemoptysis in 2 patients. Respir Care 2010;55:1094-6.  Back to cited text no. 4
    
5.Macht M, Mitchell JD, Cool C, Lynch DA, Babu A, Schwarz MI. A 31-year-old woman with hemoptysis and an intrathoracic mass. Chest 2010;138:213-9.  Back to cited text no. 5
    
6.Asteriou C, Barbetakis N, Kleontas A, Konstantinou D. Giant mediastinal teratoma presenting with paroxysmal atrial fibrillation. Interact Cardiovasc Thorac Surg 2011;12:308-10.  Back to cited text no. 6
    
7.Pikin O, Kolbanov K, Kazakevich V, Korolev A. Mediastinal mature cystic teratoma perforating into the lung. Interact Cardiovasc Thorac Surg 2010;11:827-9.  Back to cited text no. 7
    
8.Turna A, Ozgül A, Kahraman S, Gürses A, Fener N, Yilmaz V. Primary pulmonary teratoma: Report of a case and the proposition of "bronchotrichosis" as a new term. Ann Thorac Cardiovasc Surg 2009;15:247-9.  Back to cited text no. 8
    
9.Giunchi F, Segura JJ. Primary malignant teratoma of lung: Report of a case and review of the literature. Int J Surg Pathol 2012; 20:523-7.  Back to cited text no. 9
    

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Correspondence Address:
Rathna Nuti
239 Glen Ridge Drive, Murphy, TX 75094
USA
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0377-4929.118671

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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]

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