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J Thorac Cardiovasc Surg 2006;132:191-192
© 2006 The American Association for Thoracic Surgery
Brief Communication |
a Unité de Chirurgie Thoracique, Hôpital Hôtel-Dieu, AP-HP, Université Paris V, Paris, France
b Service d'Anatomie et de Cytologie Pathologiques, Hôpital Hôtel-Dieu, AP-HP, Université Paris V, Paris, France
Received for publication February 6, 2006; accepted for publication March 15, 2006. * Address for reprints: Marco Alifano, MD, Unité de Chirurgie Thoracique, Hôtel-Dieu 1, place du Parvis Notre Dame, 75181 PARIS Cedex 04, France. (Email: marcoalifano{at}yahoo.com).
Carcinoma showing thymus-like elements (CASTLE) is a rare cervical tumor. Approximately 30 cases have been reported in the English language literature.
1
In 1985, Miyauchi and colleagues
2
reported the first series dealing with this type of tumor. Although generally thought to have a less-marked malignant behavior compared with thyroid carcinomas, CASTLE may progress and result in death.
Clinical Summary
A 63-year-old woman had anterior cervical swelling 6 months before admission to our unit. Assessment in another institution by ultrasonography and computed tomography (CT) scan showed a tumor close to the lower pole of the left thyroid lobe, causing right and backward tracheal dislocation. There were no enlarged lymph nodes. The lesion was misdiagnosed as a thyroid goiter, and cervicotomy was planned. At surgery a tumor was found infiltrating the strap muscles and trachea, but independent of the thyroid and thymus. No resection was attempted. Because of the absence of a preoperative diagnosis and inconclusive data from the frozen-section examination, only biopsies were taken. The pathologic diagnosis was thymic carcinoma. The patient was referred to our institution for subsequent management.
A novel CT scan was consistent with tumoral progression, compared with the first CT scan performed 3 months previously. Fiberoptic bronchoscopy showed an extrinsic compression of the trachea starting 3 cm caudally to the vocal cords and involving 4 tracheal rings. 18-FDG positron emission tomography showed an isolated hypermetabolic focus corresponding to the cervical tumor. We decided to perform another surgical exploration. At cervicosternotomy, invasion of the sternothyroid muscle and trachea by a 6-cm tumor was confirmed. The lesion infiltrated the upper portion of left thymic lobe and was in close contact with the lower aspect of the left lobe of the thyroid. An en bloc resection of the thymus, sternothyroid muscle, trachea (8 rings), and lower aspect of the left thyroid lobe was performed. For technical reasons, the tumor was removed en bloc with the cartilaginous portion of the trachea. The membranous part, which was completely free of the tumor, was removed secondarily under jet ventilation. A termino-terminal tracheal anastomosis was performed after laryngeal and tracheal release with dissection of both mainstem bronchi.
Pathologic examination (Figure 1) showed a tumoral proliferation invading the tracheal cartilage (without involvement of the mucosa), the lower pole of the left thyroid lobe, the left superior horn of the thymus, and the sternothyroid muscle. The surgical margins were free. Nodal metastases were found in 4 cervical lymph nodes. At light microscopy, tumor growth in the form of variably sized islands separated by thick fibrous trabeculae was observed. Cytoplasm was abundant and eosinophilic, whereas nuclei were oval with distinct nucleoli and granular chromatin. Nuclear atypia was moderate, and some areas of necrosis were observed. Mitotic figures were also present. The cells were immunohistochemically KL1+, EMA+, CD5+, CD117+, chromogranin A+, and TTF1–.
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Discussion
CASTLE is an extrathymic tumor occurring at the cervical level in the trajectory of embryonal migration of the thymus (between the mandibular angle and the retrosternal region). The lesion may arise either inside the thyroid gland (in this case it was located in the lower portion of the lobes) or in the latero-tracheal region.
In our patient, the tumor did not have any contact with the thyroid at the time of the first surgical exploration. The spontaneous evolution of this tumor at 3 months was responsible for the subsequent limited invasion of both the thymus and thyroid.
Compared with patients with thyroid carcinoma, patients with CASTLE seem to have a better prognosis. However, CASTLE has a potentially invasive behavior, and invasion of neighboring cervical structures is possible. In particular, tracheal
2
or laryngotracheal
3
resections have been necessary to excise the lesion. The extent of this invasion may sometimes prevent a complete resection
1
or require surgically challenging procedures, as in our experience. The parietal invasion can involve the muscles, connective tissue, and skin.
4,5
Nodal involvement is probably a negative prognostic factor, because it has been associated with the occurrence of locoregional
3
or systemic spread.
1,2
Adjuvant radiotherapy is generally advocated in case of nodal metastasis. On the other hand, local recurrence is possible in the absence of nodal disease, thus suggesting a role for systematic adjuvant radiotherapy because of the radiosensitivity of this tumor.
1
References
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