World Journal of Cardiovascular Surgery, 2013, 3, 111-113 Published Online July 2013 (
Huge Congenital Thymic Cyst with Microscopic Thymoma
Alberto Terminella1, Giacomo Cusumano1*, Ignazio Vasta1, Rosalia Giarlotta1, Salvatore Bellofiore1,
Carmelo Riscica Lizzio1, Salvatore Saita1, Maria D’Arrigo2
1Division of General Thoracic Surgery, “Vittorio Emanuele—Policlinico” Hospital, Catania, Italy
2Department of Histopathology, “Vittorio Emanuele—Policlinico” Hospital, Catania, Italy
Email: *
Received November 13, 2012; revised December 20, 2012; accepted December 28, 2012
Copyright © 2013 Alberto Terminella et al. This is an open access article distributed under the Creative Commons Attribution Li-
cense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
The congenital thymic cysts are rare. They have a congenital origin and they are benign. The differential diagnosis of
acquired cysts, cystic thymoma and thymic malignancies in cystic degeneration can be particularly difficult. Rarely,
they assume clinical relevance for the appearance of symptoms of compression, more typical of malignant lesions, and
the association with thymoma was reported in very few cases in literature. For all these features, treatment strategy re-
mains controversial and in particular surgical approach. We report a case of a huge symptomatic congenital thymic cyst,
surgically removed with histological finding of microscopic thymoma.
Keywords: Thymic Cystis; Thymoma; Mediastinal Tumor; Surgery
1. Case Report
A 40-year-old woman was admitted to our hospital with
worsening dyspnoea and chest pain. Her medical history
revealed a previous percutaneus aspiration of mediastinal
cyst, which occurred 5 years before, physical examina-
tion, and laboratory findings were normal. The chest
X-ray showed an upper mediastinal enlargement. The CT
scan revealed a homogenous mediastinal cystic lesion,
with approximately maximal diameter of 20.2 cm. The
cyst occupies the anterior mediastinum and the ante-
rior-lower space of both hemithorax, without evidence of
infiltration of surrounded tissues (Figure 1).
The clinical and radiological presentation and the pre-
vious history, direct our choice to a symptomatic “relapse
of thymic cyst” and to the decision of surgical approach.
Patient underwent radical transternal thymectomy through
an inframammary 10 centimetres vertical cutaneus inci-
sion. Surgical exploration revealed a well-encapsulated
cystic bilobe formation 17 × 16 × 11 centimetres with
thin cystic wall within the right inferior lobe of the thy-
mus. The cystic contains a serous liquid. Postoperative
time was uneventful.
Histological examination revealed that cysts were par-
tially lined by small cuboidal cells with fibrous-adipoose
thin wall, which focally showed thickening containing
small foci of lymphoid tissue with Hassal bodies (Fi-
gure 2A). Between the cyst and the thymic horn, a small
area was found with neoplastic thymic elements com-
posed of spindled to oval epithelial cells with large nu-
cleus and evident nucleulus nucleolus. The pathological
diagnosis was thymoma in pre-existing thymic cyst
(Figure 2B).
2. Discussion
Benign thymic cysts represent approximately 1% of all
anterior mediastinal masses. They can be congenital or
acquired, unilocular or multilocular and frequently, they
are asymptomatic. Congenital cysts are usually unilocu-
lar with thin walls lined by squamous or small columnar
cells and containing clear fluid; they show no evidence of
inflammation. They probably origin originate from fetal
thymopharyngeal tract. While, acquired cysts, result from
an inflammatory process, are often multiloculated, con-
tain chocolate colored fluid or gelatinous material and
they have thick fibrous walls characterized by inflame-
matory process [1-3].
Cystic thymoma and cystic degeneration of the larger
thymoma are common, exceptional thymomas is found in
the contest of the cyst, especially in congenital cysts ones
in which arise from the cystic wall, suggesting that neo-
plastic change could occur in a simple thymic cyst [4-6].
In summary, thymoma occurs even in case of congenital
thymic cyst.
*Corresponding author.
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Figure 1. Thorax CT scan: homogenous mediastinal cystic lesion that occupies the anterior mediastinum.
Figure 2. (2A) Microscopic findings of the specimen show a congenital cyst lined with squamous or cuboidal epithelium; (2B)
Histological finding of microscopic thymoma.
Copyright © 2013 SciRes. WJCS
Our case confirms the possible onset of microscopic
foci of thymoma in the context of congenital cyst but the
role of this last in the onset of thymoma is still not clear.
Our case strengthens the need of a follow-up, even in
case of congenital cysts and raises the question of a pos-
sible surgical treatment in this group of patients.
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