Management
Surgical excision is generally indicated in symptomatic lesions or
lesions with large cystic components. However, since thymic tissue
involutes with increasing age, conservative management and follow-up
might be appropriate in cases of asymptomatic solid lesions.
Notably, ECT could be the only active
thymus and an absent mediastinal thymus has been documented in 50% of
these patients.3 Wells et al reported that infants who
are thymectomized under the age of 1 year show a significant decrease in
total T cell counts (especially the CD2 and CD4 subsets) although they
have no increase in the frequency of infections.80Therefore, careful consideration should be taken prior to excision of an
ECT in children as this might lead to potential immuno-incompetence.
Furthermore, thymic involution starts prior to adolescence, with a
decline averaging 1% per year81 and therefore a solid
ECT could regress over time as the lesion is rarely found in adults. The
most relevant findings in our systematic review is that cystic lesions
are much bigger and identified at a much older age compared to solid
lesions. This is secondary to the natural involution of the thymus
tissue with time, and asymptomatic solid ECT could be managed
conservatively. In older children, when the ECT has undergone
degeneration with formation of large cysts, surgical excision might be
appropriate as these will likely not have immunological
function.57
One advantage of the surgical excision of an ECT is the potentially
malignant transformation of this lesion. However, cervical thymoma is an
extremely rare entity, with twenty cases (three malignant) currently
reported in the literature, presenting at an average age of 45
years.18
Pirkey in 1954 reported a paediatric case of thymoma arising in a ECT,
which was non-metastatic.82 Lewis, in a review of 32
cases of ECT documented malignant cells only in a tracheal mass of a
58-year-old female.83 In addition, there is no data
indicating that the incidence of malignant transformation of ECT is any
greater than in normal thymic tissue. Furthermore, from our systematic
review of the last 20 years, we did not identify any case of malignancy,
suggesting that ECT is a benign lesion in children.
Finally, it is important to highlight that surgical excision of an ECT
in children might have significant morbidity. As with our described
case, the lesion is often adherent to surrounding structures, such as
the carotid artery, the jugular vein, and/or the vagus, hypoglossal,
phrenic, and recurrent laryngeal nerves. Additionally, 50% have shown a
mediastinal connection that could require a sternotomy for complete
excision further supporting a conservative approach in asymptomatic
lesions.65