Interactive Cardiovascular and Thoracic Surgery 2:537-540(2003)
© 2003 European Association of Cardio-Thoracic Surgery
Case report - Thoracic general |
Concurrent epithelial thymoma and T-cell lymphoblastic lymphoma
Francesca Roveraa,
Paola Billob,
Carlo Capellab and
Lorenzo Dominionia,*
a Center for Thoracic Surgery, University of Insubria, Ospedale di Circolo di Varese, Viale Borri 57, 21100 Varese, Italy
b Service of Anatomic Pathology, University of Insubria, Varese, Italy
* Corresponding author. Tel.: +39-0332-278868; fax: +39-0332-264169
dom{at}skylink.it
Received February 5, 2003;
received in revised form May 12, 2003;
accepted June 16, 2003
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Abstract
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The occurrence of an epithelial thymoma concomitant with a primary thymic T-cell lymphoblastic lymphoma is rare. This paper describes the case of a patient with a synchronous epithelial thymoma and thymic T-cell lymphoblastic lymphoma, characterized by a rapidly fatal clinical course. A review of the literature is reported.
Key Words: Thymoma; Thymic T-cell lymphoblastic lymphoma; Thymic tumor
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1. Introduction
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Thymoma is the most frequent benign or low-grade malignant thymic tumor [1,2]. The neoplastic epithelial component of thymoma is frequently associated with mature or immature T-cell lymphocytes; only few cases of concomitant thymic T-cell lymphoma, however, are reported (Table 1). We describe a case of thymic tumor composed of an epithelial thymoma and a T-cell lymphoblastic lymphoma.
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2. Case history
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A 65-year-old white male was admitted to our thoracic surgery unit in December 1998 for an asymptomatic mediastinal mass, incidentally detected by chest X-rays. That radiography was taken as a workup examination before surgery for discal hernia. Except for hernia-related lumbosciatalgia, the patient was otherwise asymptomatic and was in good general condition. He denied chest pain, breathing difficulty or fever. When he was admitted to hospital, physical examination did not show alterations related to the mediastinal mass. Routine blood chemistry tests were normal. Thoracic imaging exams were ordered: chest computed tomography (CT) scan confirmed the anterior mediastinal mass, 12 cm in largest diameter, close to the pericardium and to the great vessels, without signs of invasion or pleural effusion. Spirometry, thyroid scintigraphy and abdomen ultrasonography scan were normal. On the basis of these findings, the diagnosis of suspected thymoma was made. In January 1999 the patient underwent median sternotomy and radical resection of the mediastinal mass, including dissection of perithymic fat and mediastinal lymphadenectomy. The mass was encapsulated, with firm consistence and with intermingled cystic areas. The histologic diagnosis was: ‘thymoma of prevalent epithelial type with mixed oval and spindle cells’. The thymoma was classified as type AB (mixed) [9]. The lymphoid component contained active cells increased in size. No neoplastic cells were observed in the mediastinal lymph nodes removed with the thymoma. The postoperative course was uneventful and the patient was discharged after 12 days, convalescent.
After discharge the patient remained in good health for 3 months. Then he developed dyspnea, fever, weakness and small erythematous non-tender skin nodules in the head and neck area. The hematologic examinations showed white blood cell count of 15 110/µl, with marked eosinophilia (38%); lymphocytes were 13%, neutrophils 36%, monocytes 12%. Renal function indices were altered. Skin nodule biopsy demonstrated a diffuse dermic-hypodermic infiltrate of round lymphoid cells, diagnosed as T-cell lymphoblastic lymphoma. We then reviewed the thymic mass slides and noted that the thymoma lymphoid component was morphologically and immunophenotypically (Fig. 1) similar to the cutaneous T-cell lymphoblastic lymphoma. The 3-month postoperative re-staging by CT imaging of the chest, abdomen and brain showed no abnormalities; bone marrow biopsy was also normal. The initial diagnosis of ‘thymoma type AB’ was revised and changed to ‘concurrent epithelial thymoma and T-cell lymphoblastic lymphoma’. Consequently, the patient was treated with chemotherapy, consisting in three cycles of methotrexate, adriamycin, cyclophosphamide, vincristine, bleomycin and prednisone. In July 1999, 7 months after the initial incidental diagnosis of the mediastinal mass, the patient's general conditions worsened and further follow-up imaging exams detected suspected hepatic and cerebral metastases. Liver biopsy and cerebrospinal fluid cytology demonstrated metastases of T-cell lymphoblastic lymphoma. Biopsy of inguinal lymph nodes and of bone marrow, however, demonstrated no involvement. Subsequently the patient's clinical conditions rapidly worsened and death ensued from cachexia due to widespread lymphoma diffusion, 8 months after the initial diagnosis.
2.1. Histopathologic and immunohistochemical study
The histologic sections of the mediastinal mass were stained with hematoxylin–eosin and Giemsa. Immunoperoxidase stains for AE1/AE3 cytokeratins, CD1a, CD3, CD20, CD45, CD45RO and Tdt were performed using the avidin–biotin technique. The tumor presented a prevalent epithelial component (Fig. 1a) made of polygonal and spindle cells strongly reactive for cytokeratins (Fig. 1b), and a lymphoid component in clusters (Fig. 1c); the latter showed a prevalence of medium-sized cells with scanty cytoplasm, convoluted nuclei with finely dispersed chromatin and high mitotic activity. The neoplastic lymphoblasts were CD1a (Fig. 1d), Tdt and CD3 immunoreactive.
The skin nodule histologic features (Fig. 1e) were similar to the T-cell lymphoblastic component of the thymoma; the immunohistochemical reactivity was the same (Fig. 1f) as in the T-cell lymphoblastic component of the thymoma.
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3. Discussion
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Concurrent epithelial thymoma and primary thymic T-cell lymphoblastic lymphoma is rare; the few cases reported in the literature are summarized in Table 1. Our study describes a mediastinal mass made of two components: epithelial thymoma and T-cell lymphoblastic lymphoma. The epithelial component showed low mitotic index and benign features. The lymphoid component featured immature and activated cells, confined within the thymus, without nodal involvement. Initially the histologic and immunohistochemical findings were consistent with mixed AB thymoma showing an activated non-neoplastic lymphoid component. The appearance of a cutaneous T-cell lymphoblastic lymphoma 3 months later, however, suggested that the cutaneous neoplasm could be secondary to an underevaluated neoplastic component of the thymic tumor.
Among the few reports of thymoma and concomitant thymic T-cell lymphoma, only Macon et al. [8] described a case similar to ours. Both presented a benign encapsulated epithelial thymoma intermingled with blast-like lymphocytes, without the widely infiltrative growth typical of the T-lymphoblastic lymphoma. Nevertheless, the involvement of mediastinal lymph nodes by T-lymphoblasts in Macon's case [8], and the subsequent development of T-lymphoblast metastases in our case, prove the malignant nature of the lymphoid cells. Indeed the Tdt and CD1a positivity of the cutaneous lymphoblastic infiltrates confirms, in our case, their thymic origin.
Peripheral T-cell lymphocytosis is rarely associated with thymoma, although some authors reported this finding associated with an invasive thymoma [2,6,7]. In our patient eosinophilia developed, without lymphocytosis. The malignant lymphoid component described by Macon et al. [8] appeared in a recurrent thymoma after radiation therapy. In our patient the thymoma was detected incidentally; epithelial thymoma and T-lymphoblastic lymphoma co-existed in the same mass, although the lymphoma was not recognized at the beginning. This pitfall emphasizes that a lymphomatous component can be misinterpreted as an activated non-neoplastic lymphoid component of a lymphocyte-rich thymoma. A low mitotic index is useful to distinguish ‘activated’ (lymphoblast-like) non-neoplastic lymphocytes within a benign thymoma, from high-mitotic-index malignant lymphoblasts.
Thymoma remains a field of intriguing clinico-pathologic interest. The case we report emphasizes that a very careful evaluation of all thymoma components is necessary for a correct diagnosis.
doi:10.1016/S1569-9293(03)00136-1
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References
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- Thomas J, De Wolf-Peeters C, Tricot G, Bekaert J, Broeckaert-Van Orshoven A. T-cell chronic lymphocytic leukemia in a patient with invasive thymoma in remission with chemotherapy. Cancer. 1983;52:313–317[Medline]
- Doll DC, Landreneau RJ, List AF. Malignant thymoma associated with peripheral T-cell lymphocytosis. Med Pediatr Oncol. 1991;19:496–498[Medline]
- Smith GP, Perkins SL, Segal GH, Kjeldsberg CR. T-cell lymphocytosis associated with invasive thymomas. Am J Clin Pathol. 1994;102:447–453[Medline]
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- Rosai J, Sobin LH. WHO international histological classification of tumors – histological typing of tumours of the thymus. 2nd ed. Berlin: Springer; 1999.
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Top
Abstract
1. Introduction
. (b) Cytokeratin immunoreactivity of tumor epithelial cells (immunoperoxidase, 
. (c) Lymphomatous component of the thymic tumor showing sheets of lymphoblasts positive for CD1a (hematoxylin–eosin, 
. (d,e) Skin lymphoblastic lymphoma, immunoreactive for CD1a (f) (immunoperoxidase,