A Rare Case of Thymic Carcinoma

doi:10.4236/ss.2011.23030

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Surgical Science, 2011, 2, 144-146

doi:10.4236/ss.2011.23030 Published Online May 2011 (http://www.scirp.org/journal/ss)

A Rare Case of Thymic Carcinoma

Farshad Anvari1, Arnold M. Schwartz2, Gregory Trachiotis1

1 Department of Surgery, Division of Cardiothoracic Surgery,

The George Washington University, Washington, DC, USA

2 Department of Pathology, The George Washington University, Washington DC, USA

E-mail: [email protected] u

Received February 3, 2011; revised April 4, 2011; accepted April 18, 2011

Abstract

Thymic carcinomas are unusual tumors of the thymus gland. Basaloid carcinoma, an unusal epithelioid vari-

ent of a thymic carcinoma, is a rare histopathological subtype, and is not well charecterized in the literature.

We present the anatomical and histogical features of a basoloid thymic carcinoma, and discuss current diag-

nosis and imaging strategies, as well as the operative and oncologic care of this type of thymmic carcinoma.

Basaloid carcinomas of the thymus after complete surgical resection and adjuvant therapy genarally have a

favorable long-term prognosis.

Keywords: Thymus; Thymic Carcinoma

1. Introduction

Thymomas are the second most common tumors of the

mediastinum; however, they are relatively uncommon

tumors and often discovered on imaging studies of the

chest performed for other reasons [1]. Thymic carcino-

mas are even rarer, accounting for 10% if all thymic tu-

mors, but they still remain a significant disease because

of their invasiveness and behave biologically different

than other tumors of the thymus gland [2-5].We report a

case of basaloid thymic carcinoma, one of the rarest

variants of thymic carcinomas, and discuss diagnostic,

operative and oncologic management.

2. Case Summary

A 64 year old male with no significant past medical his-

tory presented to the emergency room with one day his-

tory of myalgia, arthralgia, vertigo and shortness of

breath with chest pressure. The patient had been experi-

encing right sided chest pain not related to exercise. The

patient had a normal physical examination, and specifi-

cally no neurologic defects and a normal testicular exam.

The chest radiograph showed a widened mediastinum,

and a cardiac evaluation was negative, and and chest

computerized tomogram (chest CT) to evaluate for pul-

monary embolus demonstrated an anterior medicastinal

mass masuring 3.9 cm × 5.9 cm (Figure 1). Serum

markers including alpha-fetoprotein, human choriogo-

Figure 1. Chest computed tomography on admission show-

ing an anterior mediastinal tumor.

nadotropin (HCG), CA-19-9, human immunodeficiency

virus (HIV), and markers for myasthenia gravis were

normal. A testicular ultrasound which was also obtained

was negative. Preoperative cardiopulomonary testing

was normal. The patient was scheduled for elective thy-

mectomy. The exposure of the mediastinum via a ster-

notomy and revealed a large thymic mass grossly meas-

F. ANVARI ET AL. 145

(a)

(b)

Figgure 2. (a) Cut gross section of completely resected

thymic carcinoma; (b) Histopathologic examination (× 10)

of the basaloid thymic carcinoma showing cells in a palisad-

ing arrangement.

uring 8.5 cm × 6 cm × 2 cm that was densely adherent to

the pericardium and extending down over the right

atrium (Figure 2(a)). The thymic fat and tissue were

removed en bloc with a portion of pericardium to ensure

complete resection margins. Histology demonstrated a

basaloid thymic carcinoma, low grade, with no lym-

phovascular invasion (Figure 2(b)). All margins were

negative, and lymph nodes included in the specimen was

also negative for metastatic carcinoma. Postoperative

course was uneventful. This tumor was classified as a

World Health Organization (WHO) stage B3 or a

Masoaka stage III. The patient received adjuvant radia-

tion therapy totaling 60Gy. He remains tumor free after

36 months.

3. Discussion

Thymomas are the second most common tumors of the

mediastinum (21%) and the most common neoplasm of

the anterosuperior mediastinum [1,2]. However, the inci-

dence of thymic carcinomas is small and basaloid thymic

carcinoma is one of the rarest variants. We found only 16

reported cases of basaloid thymic carcinomas in our

search of PubMed database [5]. Thymic carcinomas are

divided histologically into low-grade and high-grade

tumors [2,3,6-8]. Basaloid carcinomas are low-grade

tumors with a favorable prognosis compared to other

forms of thymic carcinomas. Heterogeneity of thymomas

has made classification of these tumors difficult. Several

classification systems have been developed over the

years; the most common classification systems used are

the World Health Organization (WHO) system and the

Masaoka system [2,3,8].

Patients usually have symptoms at presentation, and

symptoms may be related to local mass effects causing

chest pain, dyspnea, hemoptysis, cough, and the superior

vena caval syndrome [1,2,8]. Most often the first diag-

nostic test after presentation is a chest X-ray, which is

non-specific and will point to a mediastinal abnormality.

Computed tomography is the modality of choice in diag-

nosis of thymomas. Magnetic resonance imaging is also

frequently used, and has great value in surgical planning,

especially if the tumor is invading adjacent structures

based on initial imaging [2,8]. Positron emission tomo-

graphy (PET) has emerged as a potential diagnostic tool

to help distinguish a benign versus malignant neoplasm

within the thymic gland; thus, potentially aiding in

therapuetic management, such as dictating an intial op-

erative approach versus biopsy [2,9]. Nonetheless, the

utility of PET imaging for providing diagnostic acuracy

for thymic carcinomas versus of malifnant neoplasms of

the anterior mediatinum is still under evaluation [2,9].

Fine needle aspiration is used by some to diagnose

mediastinal tumors. However, many programs, including

ours, do not use FNA routinely for concern of seeding of

the tract or mediastinum with tumor cells [2,8]. A com-

bination of blood tests for tumor markers, and testicular

ultrasonography in men, can avoid uneccasary surgical

intervention. In all other cases, diagnosis can be made at

the time of surgical resection.

Surgery is the mainstay of treatment for thymomas

with potential to cure. Our operative approach for ante-

rior mediastinal masses is median sternotomy, as is fa-

vored by most for resecting thymic tumors, especially

when thymic carcinoma is suspected [2,8]. The extent

and completeness of the resection is an important factor

in determining local recurren ce and survival [2,4,8].

Adjuvant radiation therapy remains controversial for

completely resected Masaoka stage I and II tumors of the

thymus. Adjuvant radiation has been shown to signifi-

cantly increase 5-year survival rate (86% VS. 48%); es-

pecially in high risk Masaoka stage II tumors in the

WHO categories of B2, B3, or C [1,2,7,8]. A number of

studies have shown that changing radiation field or dose

does not change survival [7]. Opinion in regards to adju-

vant radiotherapy for Masaoka stage III thymomas is

F. ANVARI ET AL.

146

divided with some studies showing no significant sur-

vival difference between surgery alone and surgery with

radiation [4,8]. However, other studies have demon-

strated that adjuvant radiotherapy for advanced thymo-

mas, particularly Masaoka stage III, has long-term bene-

fits with complete or partial remission [2,8].

Chemotherapy is not considered a treatment of choice

when complete resection can be achieved [5]. However,

cisplatin-based protocols have been used in patients with

unresectable disease or gross residual disease [3]. Cur-

rently there are no standardized regimens.

In this case, we were able to achieve a complete resec-

tion of a basaloid thymic carcinoma, which as single

therapy has a 5 year survival rate of 92.9% for a Ma-

saoka stage III tumor [4]. Although the low-grade nature

of basaloid thymic carcinoma, based on macroscopic

invasion of the pericardium (Masaoka stage III) and his-

tology features (WHO B3) in this case, adjuvant radio-

therapy was added, and should enhance the overall fa-

vorable prognosis of this unusu a l thymic tumor.

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