- Email: [email protected]
Late onset immunodeficiency in a patient with recurrent thymic carcinoma and myasthenia gravis
Journal of Neurological Sciences 157 (1998) 201–205
Late onset immunodeficiency in a patient with recurrent thymic carcinoma and myasthenia gravis a, b Stephan Schmidt *, Frank Padberg a
¨ ), Sigmund-Freud-Str. 25, 53105 Bonn, Germany Department of Neurology, University of Bonn ( Rheinische Friedrich Wilhelms-Universitat b ¨ ), Nußbaumstraße 7, 80336 Munchen ¨ , Germany Department of Psychiatry, University of Munich ( Ludwig-Maximilians-Universitat Received 24 June 1997; received in revised form 8 January 1998; accepted 16 January 1998
Abstract The most common autoimmune disease associated with thymoma is myasthenia gravis. In addition, cellular and humoral immune defects have been frequently reported in association with thymic neoplasms. Here we report the case of a patient with myasthenia gravis receiving long-term immunosuppression with azathioprine and recurrent well-differentiated thymic carcinoma who developed CD41 T-cell depletion and CNS cryptococcosis after multiple courses of chemotherapy and mediastinal irradiation. We hypothesize that in thymectomized patients bone marrow suppression and abrogation of the peripheral T-cell pool can result in a delayed T-cell regeneration due to the lack of functional thymic epithelium. 1998 Elsevier Science B.V. Keywords: Myasthenia gravis; Thymectomy; Immunodeficiency; Thymic carcinoma; CD41 T-cells
1. Introduction Neoplasms of the thymus (thymomas) are associated with myasthenia gravis [1–3] and a variety of other putatively autoimmune conditions of the hematopoetic system [1,4–9] as well as with humoral and cellular immune defects such as hypogammaglobulinemia [1,8,10], mucocutaneous candidiasis [1,9,11–14], Kaposi’s sarcoma [15] and cryptococcal meningitis [16,17]. Thymomas derive from thymic epithelial cells representing a heterogenous group of neoplasms [18–20]. Whilst medullary and mixed thymomas largely retain their organotypic structure without exhibition of invasive features histopathologically, undifferentiated thymic carcinomas almost always grow invasively [19,20]. The association of thymomas with parathymic autoimmune disease also depends on the underlying thymic pathology, e.g. welldifferentiated thymic carcinoma, an organotypical low-
*Corresponding author. Tel.: 149 228 2876380; fax: 149 228 2875024 0022-510X / 98 / $19.00 1998 Elsevier Science B.V. All rights reserved. PII S0022-510X( 98 )00085-9
grade thymic carcinoma, has the highest association with myasthenia gravis [20]. It is generally accepted that the peripheral T-cell repertoire is shaped within the thymus: T-cell precursors from hematopoetic sources migrate into the thymus, and mature through several phenotypic intermediates by positive and negative selection mechanisms [21]. Although the thymus undergoes rapid involution starting after the first year of life, a residual role in lymphocyte maturation is maintained throughout life although the immunological significance of this finding has remained unclear [22]. For example, in immunocompetent adults, thymectomy does not result in peripheral lymphocytopenia or in cellular immune deficiency [23,24]. Moreover, experimental and clinical data indicate that T-cell development and regeneration might also take place in extrathymic sites [25,26]. Clinically, the mechanisms of adult T-cell regeneration are of vital importance in those patients in whom either the pool of (mature) peripheral T-cells or the pool of prethymic (bonemarrow derived) T-cells is depleted, or both. Here we report the case of a patient with myasthenia gravis receiving long-term immunosuppression with
202
S. Schmidt, F. Padberg / Journal of Neurological Sciences 157 (1998) 201 – 205
azathioprine and recurrent well-differentiated thymic carcinoma who developed CNS cryptococcosis and peripheral CD41 lymphocytopenia after repeated courses of systemic chemotherapy and mediastinal irradiation. The possible mechanisms of cellular immune deficiency are discussed in light of the extremely rare combination of immunosuppressive treatments in our patient. We hypothesize that in thymectomized patients bone marrow suppression induced by chemotherapy can cause delayed or even abrogate peripheral T-cell regeneration due to the lack of functional thymic epithelium.
2. Clinical history
2.1. Thymic carcinoma At the age of 36 a chest radiograph revealed a mass in the anterior mediastinum during routine clinical workup for thyroid gland enlargement. On CT scan the mass infiltrated the left pleura, phrenic nerve and thoracic wall. Thoracic surgery was performed with partial removal of the mediastinal mass. Histopathologically a diagnosis of thymic carcinoma of the well-differentiated type (classified according to Kirchner [18]) was made. After incomplete surgical removal of the thymic carcinoma systemic chemotherapy using carboplatin and doxorubicin in combination with fractionated mediastinal irradiation was initiated resulting in clinical and radiographic remission. After two years, pleural metastases were detected and combination therapy with systemic chemotherapy and irradiation was repeated. During the following six years one course of treatment was performed each year because of recurrent metastases, resulting in clinical and radiographic remission.
returned to normal four weeks after the chemotherapy had been stopped. Over the following three months the patient lost 10 kg in weight. She was easily fatigued, progressively confused and complained of headache and vomiting. On admission the patient was lethargic and confused. The speech was slurred. The patient was cachectic without signs of fluctuating muscular weakness. Lumbar puncture yielded 273 / mm 3 white cells. Cranial CT scan revealed bilateral iso- or hyperdense lesions in the proximity of the basal ganglia with strong enhancement of contrast material. On T2-weighted cranial magnetic resonance imaging (MRI) the lesions were hyperintense with strong enhancement on postcontrast T1-weighted images. Cryptococcus neoformans was detected in the cerebrospinal fluid by India ink stain. The cryptococcal antigen titer in the CSF was 1:4200. A detailed description of the MRI and serological findings in our patient has been given elsewhere [27]. Peripheral blood counts were normal. Differential leucocyte counts gave 83% neutrophils, 8% lymphocytes, 7% monocytes, 1% eosinophils and 1% basophils. CD41 T-cells were 20 / ml (normal range 400– 1400), CD81 T-cells 100 / ml (220–1000), B cells 20 / ml (75–530), and NK cells 170 / ml (50–500). The CD4 / CD8 ratio was 0.2. Testing for HIV1 / 2 was repeatedly negative using ELISA, polymerase chain reaction (PCR) and Western Blot techniques. Azathioprine was discontinued and intravenous fluconazole (400 mg / day) was started and continued as oral maintenance therapy after two weeks. Clinically, the patient recovered and remained well for a follow-up period of eleven months. Lymphocytopenia was still present four months after azathiaprine had been discontinued. CD41 T-cells were 100 / ml, CD81 T-cells 290 / ml, B cells 30 / ml, and NK cells 170 / ml. The CD4 / CD8 ratio was 0.3.
2.2. Myasthenia gravis 3. Discussion One year after the partial removal of well-differentiated thymic carcinoma and the first course of systemic chemotherapy and irradiation the patient developed dysarthria and difficulties in swallowing along with mild generalized weakness. Autoantibodies against acetylcholinereceptor were detected in a concentration of 15 nmol / l, and therapy with pyridostigmine 240 mg / day and 60 mg of prednisolone / day along with 100 mg azathioprine was started. Steroid medication was discontinued after 6 months. Clinically, the patient remained in full remission for the next six years with a maintaining dose of 100 mg / day azathioprine and 240 mg / day pyridostigmine.
2.3. CNS cryptococcosis Six months prior to admission the last course of chemotherapy was discontinued because of pancytopenia (Fig. 1A, B). Leucocyte, erythrocyte and platelet counts
CNS cryptococcosis has only been reported twice in patients with thymic carcinomas [16,17]. However, both patients were distinct from the patient described here. In the patient reported by Malas et al. [17], thymic carcinoma was associated with rheumatoid arthritis, systemic lupus erythematodes, CNS cryptococcosis and finally progressive multifocal leucencephalopathy but not with myasthenia gravis. Moreover, the details of thymic histopathology were not given. The patient reported by Rowland et al. [16] shares many features of our patient with mild generalized myasthenia gravis along with thymic carcinoma and CNS cryptococcosis. The thymic pathology was described as an admixture of lymphocytic and epithelial cells with abundant clear cytoplasm and large vesicular nuclei compatible with the well-differentiated carcinoma type according to Kirchner et al. [18]. However, in contrast to our case, neither the patient of Rowland et al., nor that of
S. Schmidt, F. Padberg / Journal of Neurological Sciences 157 (1998) 201 – 205
203
Fig. 1. Leucocyte counts (A) and percentage of lymphocytes (B) before and after the last course of chemotherapy. CD41 / CD81 counts on admission, after four weeks and three months of treatment (C).
Malas et al. had been thymectomized, and they had not received systemic chemotherapy [16,17]. Cellular and humoral immune defects are not uncommon in patients with thymic tumors. Altered cellular immunity has been repeatedly described in patients with thymoma and concomitant mucocutaneous candidiasis, but has not been accompanied by changes in peripheral lymphocyte numbers [9,11–14]. Another frequent immunological abnormality in patients with thymoma is hypogammaglobulinemia [1,8,10], and lymphocytes from patients with hypogammaglobulinemia suppress immunoglobulin production and erythroid differentiation in vitro [28]. Although peripheral B cell counts were decreased in
our patient, serum immunoglobulin levels were normal and immunelectrophoresis revealed regular isotype distribution (not shown). Although we cannot exclude that the welldifferentiated thymic carcinoma might have contributed to the immunodeficiency in our patient, a mere ‘thymomaassociated’ immune defect seems unlikely. With a history of multiple courses of systemic chemotherapy, mediastinal irradiation and longterm immunosuppression with azathioprine other causes of symptomatic immune deficiency have to be considered. Cryptococcus neoformans is the third most frequent infectious agent causing CNS disease in HIV infection [29]. Therefore, the acquired immunodeficiency syndrome
204
S. Schmidt, F. Padberg / Journal of Neurological Sciences 157 (1998) 201 – 205
(AIDS) was among the primary differential diagnoses in our patient. However, testing for HIV1 / 2 was repeatedly negative using ELISA, polymerase chain reaction (PCR) and Western Blot techniques. More recently, idiopathic CD41 lymphocytopenia (ICL) has been described in the absence of HIV infection [30]. However, none of the ICL patients reported had concomitant malignant disease, a history of chemotherapy and irradiation or longterm immunosuppression. Therefore, ICL can be ruled out in our patient. Mild lymphocytopenia was present in our patient (Fig. 1B) as a consequence of long-term treatment with azathioprine. Long-term immunosuppression with azathioprine is widely used in the treatment of severe generalized myasthenia gravis [31]. Azathioprine acts as a purine analogue primarily on proliferating lymphocytes and induces both B- and T-cell lymphocytopenia affecting CD41 and CD81 subpopulations equally. The most common side effect is bone marrow suppression which is easily reversible after drug withdrawal [31]. The nadir of peripheral lymphocytopenia (3.6%) in our patient was reached six months after the last chemotherapy with a predominant depletion of CD41 T-cells (Fig. 1B). It is of note that CD81 T-cells returned to normal, whilst CD41 T-cells remained significantly decreased after four months of follow-up (Fig. 1C). Moreover, peripheral lymphocytopenia persisted even after azathioprine had been discontinued for eleven months (Fig. 1B), indicating that long-term immunosuppression with azathioprine alone is not a sufficient explanation for the CD41 T-cell depletion in our patient. Finally, it could be argued that the immunosuppression was a late sequela of myelotoxicity due to chemotherapy. It is well known that chemotherapeutic agents exert a toxic influence on myelopoiesis in a dose- and time-dependent manner. Only a few anticancer agents, predominantly the alkylating drugs nitrogen mustard, cyclophosphamide, and the nitrosureas directly suppress bone marrow stem cells (reviewed by Cadman [32]). The reduction of the blood count for most other antineoplastic agents is the result of the inhibition of the proliferating committed cells in the bone marrow (reviewed by Cadman [32]). In general, maximum bone marrow suppression occurs in the most actively dividing fractions such as platelets and granulocytes. Cell-cycle specific agents, such as the antimetabolites, produce the most rapid granulocytopenic responses, but they are also associated with rapid recovery. With most agents, when given as a single therapeutic dose, the nadir of granulocyte and platelet counts occur 7–14 days later, with recovery occurring by day 21–28 [32]. The two chemotherapeutic agents used in our patient, carboplatin and doxorubicin both cause extensive myelosuppression. Carboplatin acts by cross-linking DNA, Doxorubicin is a DNA intercalator that generates free radicals. In our patient, pancytopenia occurred ten days after the initiation of the last chemotherapy. Granulopoiesis, erythropoiesis
and megakaryopoiesis returned to normal within 20–28 days, indicating that myelosuppression was reversible except for T-cell regeneration. Delayed and functionally incomplete T-cell regeneration is frequent in bone marrow transplant recipients, in whom depletion of CD41 T-cells as well as significant functional abnormalities can persist even after quantitative recovery of peripheral lymphocyte counts [25]. The role of the thymus in T-cell regeneration has been investigated in lethally irradiated animals reconstituted with syngeneic T-cell depleted bone marrow: Tcells regenerate in thymectomized animals from a peripheral pool of postthymic T-cells resulting in a ‘memory’ phenotype whilst T-cell regeneration in thymus-bearing animals results in an activation of prethymic cell populations with a ‘naive’ phenotype of T-cells [25]. These findings indicate that the T-cell regeneration seen in patients in whom the prethymic T-cell progenitors have been therapeutically eradicated, i.e. in bone marrow transplant recipients, might also follow extrathymic pathways [25,26]. However, the clinical situation of bone marrow transplant recipients is not completely applicable to our patient since bone marrow recipients are usually not thymectomized and, more importantly, receive immunosuppressive treatment to prevent graft versus host reaction after reconstitution with allogeneic T-cell depleted bone marrow [33]. In our patient, one could speculate that the last course of chemotherapy had caused depletion of prethymic T-cell progenitors in the bone marrow. However, even if these bone marrow precursors had recovered, thymic maturation would have been virtually impossible due to the lack of functional thymic epithelium. Moreover, provided that extrathymic T-cell regeneration might be present in patients without functional thymic epithelium [25,26], extrathymic T-cell regeneration was impaired due to longterm treatment with azathioprine. In conclusion, thymic T-cells generated in adulthood probably play a minor role functionally as long as the peripheral T-cell populations are preserved. In a scenario, however, where functional thymic epithelium and peripheral T-cells have been virtually eradicated, the incomplete and delayed regeneration of functional T-cells may lead to life-threatening immunosuppression.
References [1] Rosenow EC, Hurley BT. Disorders of the Thymus - A Review. Arch Intern Med 1984;144:763–70. [2] Rivner HR, Swift TR. Thymoma: Diagnosis and Management. Semin Neurol 1990;10:83–8. ¨ [3] Muller-Hermelink HK, Marx A, Geuder K, et al. The pathological basis of Thymoma-associated Myasthenia gravis. In: Penn AS, Richman DP, Ruff RL, Lennon VA, editors. Myasthenia gravis and related disorders: Experimental and Clinical Aspects. Annals of the New York Academy of Sciences, New York: The New York Academy of Sciences, 1993;681:56–65.
S. Schmidt, F. Padberg / Journal of Neurological Sciences 157 (1998) 201 – 205 [4] Geary CG, Byron PR, Taylor G, et al. Thymoma associated with pure red cell aplasia, immunoglobulin deficiency and an inhibitor of antigen-induced lymphocyte transformation. Br J Haematol 1975;29:479–85. [5] Eridani S, Whitehead S, Sawyer B, et al. Pure red cell aplasia and thymoma: demonstration of persisting inhibition of erythropoiesis after thymectomy and resolution after immune suppressive treatment. Clin Lab Haematol 1986;8:181–5. [6] Masaoka A, Hashimoto T, Shibata K, et al. Thymoma Associated With Pure Red Cell Aplasia - Histologic and Follow-Up Studies. Cancer 1989;64:1872–8. [7] Mathieson PW, O’Neill JH, Durrant STS, et al. Antibody-mediated Pure Neutrophil Aplasia, Recurrent Myasthenia Gravis and Previous Thymoma: Case report and Literature Review. Quart J Med 1990;273:57–61. [8] Mitchell EB, Platts-Mills TA, Pereira RS, et al. Acquired basophil and eosinophil deficiency in a patient with hypogammaglobulinaemia. Clin Lab Haematol 1983;5:253–7. [9] Robins-Browne RM, Green R, Katz J, et al. Pure Red Cell Aplasia, Pernicious anaemia and Candidiasis: a Defect in Immunohomeostasis. Br J Haematol 1977;36:5–13. [10] Soppi E, Eskola J, Roeyttae M, et al. Thymoma with immunodeficiency (Good’s syndrome) associated with myastenia gravis and benign IgG gammopathy. Arch Intern Med 1985;145:1704–7. [11] Rycroft RJ, Valdimarsson H, Bannister LH, et al. Chronic mucocutaneous candidiasis of late onset, thymoma and myopathy. Clin Experimental Dermatol 1976;1:59–74. [12] Kirkpatrick CH, Windhorst DB. Mucocutaneous candidiasis and thymoma. Am J Med 1979;66:939–45. [13] Stillman MA, Baer RL. Mucocutaneous candidiais and thymoma. JAMA 1973;224:628–9. [14] Ruiz-Argueelles A, Jett JR, Ritts RE. Impaired generation of helper T-cells in a patient with chronic mucocutaneuos candidiasis and malignant thymoma. J Clin Lab Immunol 1983;10:165–9. [15] Sawai T, Tuchikawa K. Kaposi’s sarcoma developed in a patient with a thymoma in the setting of excess numbers of CD8-positive cells in the peripheral blood. Arch Pathol Lab Med 1990;114:611–3. [16] Rowland LP, Griffiths CO, Kabat EA. Myasthenia gravis, thymoma and cryptococcal meningitis. N Engl J Med 1965;273:620–7. [17] Malas D, Weiss S. Progressive Multifocal Leukencephalopathy and Cryptococcal Meningitis with Systemic Lupus Erythematodes and Thymoma. Ann Neurol 1977;1:188–91. ¨ [18] Kirchner T, Muller-Hermelink HK. New Approaches to the diagnosis of thymic epithelial tumors. In: Fenoglio-Preiser CM, Wolff M, Rilke F, editors. Progress in surgical pathology. Philadelphia: Field and Wood Inc., 1989: 167–186.
205
[19] Kirchner T, Schalke B, Marx A, et al. Evaluation of prognostic features in thymic epithelial tumors. Thymus 1989;14:195–203. [20] Kirchner T, Schalke B, Buchwald J, et al. Well-Differentiated Thymic Carcinoma. Am J Surg Pathol 1992;16:1153–69. [21] Blackman M, Kappler J, Marrack P. The role of the T cell receptor in positive and negative selection of developing T cells. Science 1990;248:1335–41. [22] Steinmann GG. Changes in the Human Thymus During Aging. In: ¨ Muller-Hermelink HK, editor. The human thymus. Current topics in pathology. New York: Springer-Verlag, 1986;75:43–88 [23] Melms A, Malcherek G, Gern U, et al. Thymectomy and azathioprine have no effect on the phenotype of CD4 T lymphocyte subsets in myasthenia gravis. J Neurol Neurosurg Psychiatry 1993;56:46– 51. [24] Wijermans HJGH, Oosterhuis HJGH, Astaldi GCB, et al. Influence of adult thymectomy on immunocompetence in patients with myasthenia gravis. J Immunol 1980;124:1977–82. [25] Mackall CL, Granger L, Sheard MA, et al. T-cell regeneration after bone marrow transplantation: differential CD45 isoform expression on thymic-derived versus thymic-independent progeny. Blood 1993;82:2585–94. [26] Lefranc¸ois L, Puddington L. Extrathymic intestinal T-cell development: virtual development? Immunol Today 1995;16:16–21. [27] Schmidt S, Reiter-Owona I, Hotz M, et al. An unusual case of CNS cryptococcosis. J Clin Neurol Neurosurg 1995;97:23–7. [28] Litwin SD, Zanjani ED. Lymphocytes suppressing both immunoglobulin production and erythroid differentiation in hypogammaglobulinaemia. Nature 1977;3:57–8. [29] Levy RM, Bredesen DE, Rosenblum ML. Neurological manifestations of the acquired immunodeficiency syndrome (AIDS): experience at the UCSF and review of the literature. J Neurosurg 1985;62:475–95. [30] Smith DK, Neal JJ, Holmberg SD, et al. Unexplained opportunistic infections and CD41 T-lymphocytopenia without HIV infection. N Engl J Med 1993;328:373–9. [31] Hohlfeld R, Michels M, Heininger K, et al. Azathioprine toxicity during long-term immunosuppression of generalized myasthenia gravis. Neurology 1988;38:258–61. [32] Cadman EC, Durivage HJ. Cancer Chemotherapy. In: Wilson J, Braunwald E, Isselbacher KJ, Petersdorf RG, Martin JB, Fauci AS, Root RK, editors. Harrison’s principles of internal medicine. New York: McGraw-Hill Inc., 1991: 1587–1599. [33] Martin PJ. The role of donor lymphoid cells in allogeneic marrow engraftment. Bone Marrow Transplant 1990;6:283–9.
Late onset immunodeficiency in a patient with recurrent thymic carcinoma and myasthenia gravis a, b Stephan Schmidt *, Frank Padberg a
¨ ), Sigmund-Freud-Str. 25, 53105 Bonn, Germany Department of Neurology, University of Bonn ( Rheinische Friedrich Wilhelms-Universitat b ¨ ), Nußbaumstraße 7, 80336 Munchen ¨ , Germany Department of Psychiatry, University of Munich ( Ludwig-Maximilians-Universitat Received 24 June 1997; received in revised form 8 January 1998; accepted 16 January 1998
Abstract The most common autoimmune disease associated with thymoma is myasthenia gravis. In addition, cellular and humoral immune defects have been frequently reported in association with thymic neoplasms. Here we report the case of a patient with myasthenia gravis receiving long-term immunosuppression with azathioprine and recurrent well-differentiated thymic carcinoma who developed CD41 T-cell depletion and CNS cryptococcosis after multiple courses of chemotherapy and mediastinal irradiation. We hypothesize that in thymectomized patients bone marrow suppression and abrogation of the peripheral T-cell pool can result in a delayed T-cell regeneration due to the lack of functional thymic epithelium. 1998 Elsevier Science B.V. Keywords: Myasthenia gravis; Thymectomy; Immunodeficiency; Thymic carcinoma; CD41 T-cells
1. Introduction Neoplasms of the thymus (thymomas) are associated with myasthenia gravis [1–3] and a variety of other putatively autoimmune conditions of the hematopoetic system [1,4–9] as well as with humoral and cellular immune defects such as hypogammaglobulinemia [1,8,10], mucocutaneous candidiasis [1,9,11–14], Kaposi’s sarcoma [15] and cryptococcal meningitis [16,17]. Thymomas derive from thymic epithelial cells representing a heterogenous group of neoplasms [18–20]. Whilst medullary and mixed thymomas largely retain their organotypic structure without exhibition of invasive features histopathologically, undifferentiated thymic carcinomas almost always grow invasively [19,20]. The association of thymomas with parathymic autoimmune disease also depends on the underlying thymic pathology, e.g. welldifferentiated thymic carcinoma, an organotypical low-
*Corresponding author. Tel.: 149 228 2876380; fax: 149 228 2875024 0022-510X / 98 / $19.00 1998 Elsevier Science B.V. All rights reserved. PII S0022-510X( 98 )00085-9
grade thymic carcinoma, has the highest association with myasthenia gravis [20]. It is generally accepted that the peripheral T-cell repertoire is shaped within the thymus: T-cell precursors from hematopoetic sources migrate into the thymus, and mature through several phenotypic intermediates by positive and negative selection mechanisms [21]. Although the thymus undergoes rapid involution starting after the first year of life, a residual role in lymphocyte maturation is maintained throughout life although the immunological significance of this finding has remained unclear [22]. For example, in immunocompetent adults, thymectomy does not result in peripheral lymphocytopenia or in cellular immune deficiency [23,24]. Moreover, experimental and clinical data indicate that T-cell development and regeneration might also take place in extrathymic sites [25,26]. Clinically, the mechanisms of adult T-cell regeneration are of vital importance in those patients in whom either the pool of (mature) peripheral T-cells or the pool of prethymic (bonemarrow derived) T-cells is depleted, or both. Here we report the case of a patient with myasthenia gravis receiving long-term immunosuppression with
202
S. Schmidt, F. Padberg / Journal of Neurological Sciences 157 (1998) 201 – 205
azathioprine and recurrent well-differentiated thymic carcinoma who developed CNS cryptococcosis and peripheral CD41 lymphocytopenia after repeated courses of systemic chemotherapy and mediastinal irradiation. The possible mechanisms of cellular immune deficiency are discussed in light of the extremely rare combination of immunosuppressive treatments in our patient. We hypothesize that in thymectomized patients bone marrow suppression induced by chemotherapy can cause delayed or even abrogate peripheral T-cell regeneration due to the lack of functional thymic epithelium.
2. Clinical history
2.1. Thymic carcinoma At the age of 36 a chest radiograph revealed a mass in the anterior mediastinum during routine clinical workup for thyroid gland enlargement. On CT scan the mass infiltrated the left pleura, phrenic nerve and thoracic wall. Thoracic surgery was performed with partial removal of the mediastinal mass. Histopathologically a diagnosis of thymic carcinoma of the well-differentiated type (classified according to Kirchner [18]) was made. After incomplete surgical removal of the thymic carcinoma systemic chemotherapy using carboplatin and doxorubicin in combination with fractionated mediastinal irradiation was initiated resulting in clinical and radiographic remission. After two years, pleural metastases were detected and combination therapy with systemic chemotherapy and irradiation was repeated. During the following six years one course of treatment was performed each year because of recurrent metastases, resulting in clinical and radiographic remission.
returned to normal four weeks after the chemotherapy had been stopped. Over the following three months the patient lost 10 kg in weight. She was easily fatigued, progressively confused and complained of headache and vomiting. On admission the patient was lethargic and confused. The speech was slurred. The patient was cachectic without signs of fluctuating muscular weakness. Lumbar puncture yielded 273 / mm 3 white cells. Cranial CT scan revealed bilateral iso- or hyperdense lesions in the proximity of the basal ganglia with strong enhancement of contrast material. On T2-weighted cranial magnetic resonance imaging (MRI) the lesions were hyperintense with strong enhancement on postcontrast T1-weighted images. Cryptococcus neoformans was detected in the cerebrospinal fluid by India ink stain. The cryptococcal antigen titer in the CSF was 1:4200. A detailed description of the MRI and serological findings in our patient has been given elsewhere [27]. Peripheral blood counts were normal. Differential leucocyte counts gave 83% neutrophils, 8% lymphocytes, 7% monocytes, 1% eosinophils and 1% basophils. CD41 T-cells were 20 / ml (normal range 400– 1400), CD81 T-cells 100 / ml (220–1000), B cells 20 / ml (75–530), and NK cells 170 / ml (50–500). The CD4 / CD8 ratio was 0.2. Testing for HIV1 / 2 was repeatedly negative using ELISA, polymerase chain reaction (PCR) and Western Blot techniques. Azathioprine was discontinued and intravenous fluconazole (400 mg / day) was started and continued as oral maintenance therapy after two weeks. Clinically, the patient recovered and remained well for a follow-up period of eleven months. Lymphocytopenia was still present four months after azathiaprine had been discontinued. CD41 T-cells were 100 / ml, CD81 T-cells 290 / ml, B cells 30 / ml, and NK cells 170 / ml. The CD4 / CD8 ratio was 0.3.
2.2. Myasthenia gravis 3. Discussion One year after the partial removal of well-differentiated thymic carcinoma and the first course of systemic chemotherapy and irradiation the patient developed dysarthria and difficulties in swallowing along with mild generalized weakness. Autoantibodies against acetylcholinereceptor were detected in a concentration of 15 nmol / l, and therapy with pyridostigmine 240 mg / day and 60 mg of prednisolone / day along with 100 mg azathioprine was started. Steroid medication was discontinued after 6 months. Clinically, the patient remained in full remission for the next six years with a maintaining dose of 100 mg / day azathioprine and 240 mg / day pyridostigmine.
2.3. CNS cryptococcosis Six months prior to admission the last course of chemotherapy was discontinued because of pancytopenia (Fig. 1A, B). Leucocyte, erythrocyte and platelet counts
CNS cryptococcosis has only been reported twice in patients with thymic carcinomas [16,17]. However, both patients were distinct from the patient described here. In the patient reported by Malas et al. [17], thymic carcinoma was associated with rheumatoid arthritis, systemic lupus erythematodes, CNS cryptococcosis and finally progressive multifocal leucencephalopathy but not with myasthenia gravis. Moreover, the details of thymic histopathology were not given. The patient reported by Rowland et al. [16] shares many features of our patient with mild generalized myasthenia gravis along with thymic carcinoma and CNS cryptococcosis. The thymic pathology was described as an admixture of lymphocytic and epithelial cells with abundant clear cytoplasm and large vesicular nuclei compatible with the well-differentiated carcinoma type according to Kirchner et al. [18]. However, in contrast to our case, neither the patient of Rowland et al., nor that of
S. Schmidt, F. Padberg / Journal of Neurological Sciences 157 (1998) 201 – 205
203
Fig. 1. Leucocyte counts (A) and percentage of lymphocytes (B) before and after the last course of chemotherapy. CD41 / CD81 counts on admission, after four weeks and three months of treatment (C).
Malas et al. had been thymectomized, and they had not received systemic chemotherapy [16,17]. Cellular and humoral immune defects are not uncommon in patients with thymic tumors. Altered cellular immunity has been repeatedly described in patients with thymoma and concomitant mucocutaneous candidiasis, but has not been accompanied by changes in peripheral lymphocyte numbers [9,11–14]. Another frequent immunological abnormality in patients with thymoma is hypogammaglobulinemia [1,8,10], and lymphocytes from patients with hypogammaglobulinemia suppress immunoglobulin production and erythroid differentiation in vitro [28]. Although peripheral B cell counts were decreased in
our patient, serum immunoglobulin levels were normal and immunelectrophoresis revealed regular isotype distribution (not shown). Although we cannot exclude that the welldifferentiated thymic carcinoma might have contributed to the immunodeficiency in our patient, a mere ‘thymomaassociated’ immune defect seems unlikely. With a history of multiple courses of systemic chemotherapy, mediastinal irradiation and longterm immunosuppression with azathioprine other causes of symptomatic immune deficiency have to be considered. Cryptococcus neoformans is the third most frequent infectious agent causing CNS disease in HIV infection [29]. Therefore, the acquired immunodeficiency syndrome
204
S. Schmidt, F. Padberg / Journal of Neurological Sciences 157 (1998) 201 – 205
(AIDS) was among the primary differential diagnoses in our patient. However, testing for HIV1 / 2 was repeatedly negative using ELISA, polymerase chain reaction (PCR) and Western Blot techniques. More recently, idiopathic CD41 lymphocytopenia (ICL) has been described in the absence of HIV infection [30]. However, none of the ICL patients reported had concomitant malignant disease, a history of chemotherapy and irradiation or longterm immunosuppression. Therefore, ICL can be ruled out in our patient. Mild lymphocytopenia was present in our patient (Fig. 1B) as a consequence of long-term treatment with azathioprine. Long-term immunosuppression with azathioprine is widely used in the treatment of severe generalized myasthenia gravis [31]. Azathioprine acts as a purine analogue primarily on proliferating lymphocytes and induces both B- and T-cell lymphocytopenia affecting CD41 and CD81 subpopulations equally. The most common side effect is bone marrow suppression which is easily reversible after drug withdrawal [31]. The nadir of peripheral lymphocytopenia (3.6%) in our patient was reached six months after the last chemotherapy with a predominant depletion of CD41 T-cells (Fig. 1B). It is of note that CD81 T-cells returned to normal, whilst CD41 T-cells remained significantly decreased after four months of follow-up (Fig. 1C). Moreover, peripheral lymphocytopenia persisted even after azathioprine had been discontinued for eleven months (Fig. 1B), indicating that long-term immunosuppression with azathioprine alone is not a sufficient explanation for the CD41 T-cell depletion in our patient. Finally, it could be argued that the immunosuppression was a late sequela of myelotoxicity due to chemotherapy. It is well known that chemotherapeutic agents exert a toxic influence on myelopoiesis in a dose- and time-dependent manner. Only a few anticancer agents, predominantly the alkylating drugs nitrogen mustard, cyclophosphamide, and the nitrosureas directly suppress bone marrow stem cells (reviewed by Cadman [32]). The reduction of the blood count for most other antineoplastic agents is the result of the inhibition of the proliferating committed cells in the bone marrow (reviewed by Cadman [32]). In general, maximum bone marrow suppression occurs in the most actively dividing fractions such as platelets and granulocytes. Cell-cycle specific agents, such as the antimetabolites, produce the most rapid granulocytopenic responses, but they are also associated with rapid recovery. With most agents, when given as a single therapeutic dose, the nadir of granulocyte and platelet counts occur 7–14 days later, with recovery occurring by day 21–28 [32]. The two chemotherapeutic agents used in our patient, carboplatin and doxorubicin both cause extensive myelosuppression. Carboplatin acts by cross-linking DNA, Doxorubicin is a DNA intercalator that generates free radicals. In our patient, pancytopenia occurred ten days after the initiation of the last chemotherapy. Granulopoiesis, erythropoiesis
and megakaryopoiesis returned to normal within 20–28 days, indicating that myelosuppression was reversible except for T-cell regeneration. Delayed and functionally incomplete T-cell regeneration is frequent in bone marrow transplant recipients, in whom depletion of CD41 T-cells as well as significant functional abnormalities can persist even after quantitative recovery of peripheral lymphocyte counts [25]. The role of the thymus in T-cell regeneration has been investigated in lethally irradiated animals reconstituted with syngeneic T-cell depleted bone marrow: Tcells regenerate in thymectomized animals from a peripheral pool of postthymic T-cells resulting in a ‘memory’ phenotype whilst T-cell regeneration in thymus-bearing animals results in an activation of prethymic cell populations with a ‘naive’ phenotype of T-cells [25]. These findings indicate that the T-cell regeneration seen in patients in whom the prethymic T-cell progenitors have been therapeutically eradicated, i.e. in bone marrow transplant recipients, might also follow extrathymic pathways [25,26]. However, the clinical situation of bone marrow transplant recipients is not completely applicable to our patient since bone marrow recipients are usually not thymectomized and, more importantly, receive immunosuppressive treatment to prevent graft versus host reaction after reconstitution with allogeneic T-cell depleted bone marrow [33]. In our patient, one could speculate that the last course of chemotherapy had caused depletion of prethymic T-cell progenitors in the bone marrow. However, even if these bone marrow precursors had recovered, thymic maturation would have been virtually impossible due to the lack of functional thymic epithelium. Moreover, provided that extrathymic T-cell regeneration might be present in patients without functional thymic epithelium [25,26], extrathymic T-cell regeneration was impaired due to longterm treatment with azathioprine. In conclusion, thymic T-cells generated in adulthood probably play a minor role functionally as long as the peripheral T-cell populations are preserved. In a scenario, however, where functional thymic epithelium and peripheral T-cells have been virtually eradicated, the incomplete and delayed regeneration of functional T-cells may lead to life-threatening immunosuppression.
References [1] Rosenow EC, Hurley BT. Disorders of the Thymus - A Review. Arch Intern Med 1984;144:763–70. [2] Rivner HR, Swift TR. Thymoma: Diagnosis and Management. Semin Neurol 1990;10:83–8. ¨ [3] Muller-Hermelink HK, Marx A, Geuder K, et al. The pathological basis of Thymoma-associated Myasthenia gravis. In: Penn AS, Richman DP, Ruff RL, Lennon VA, editors. Myasthenia gravis and related disorders: Experimental and Clinical Aspects. Annals of the New York Academy of Sciences, New York: The New York Academy of Sciences, 1993;681:56–65.
S. Schmidt, F. Padberg / Journal of Neurological Sciences 157 (1998) 201 – 205 [4] Geary CG, Byron PR, Taylor G, et al. Thymoma associated with pure red cell aplasia, immunoglobulin deficiency and an inhibitor of antigen-induced lymphocyte transformation. Br J Haematol 1975;29:479–85. [5] Eridani S, Whitehead S, Sawyer B, et al. Pure red cell aplasia and thymoma: demonstration of persisting inhibition of erythropoiesis after thymectomy and resolution after immune suppressive treatment. Clin Lab Haematol 1986;8:181–5. [6] Masaoka A, Hashimoto T, Shibata K, et al. Thymoma Associated With Pure Red Cell Aplasia - Histologic and Follow-Up Studies. Cancer 1989;64:1872–8. [7] Mathieson PW, O’Neill JH, Durrant STS, et al. Antibody-mediated Pure Neutrophil Aplasia, Recurrent Myasthenia Gravis and Previous Thymoma: Case report and Literature Review. Quart J Med 1990;273:57–61. [8] Mitchell EB, Platts-Mills TA, Pereira RS, et al. Acquired basophil and eosinophil deficiency in a patient with hypogammaglobulinaemia. Clin Lab Haematol 1983;5:253–7. [9] Robins-Browne RM, Green R, Katz J, et al. Pure Red Cell Aplasia, Pernicious anaemia and Candidiasis: a Defect in Immunohomeostasis. Br J Haematol 1977;36:5–13. [10] Soppi E, Eskola J, Roeyttae M, et al. Thymoma with immunodeficiency (Good’s syndrome) associated with myastenia gravis and benign IgG gammopathy. Arch Intern Med 1985;145:1704–7. [11] Rycroft RJ, Valdimarsson H, Bannister LH, et al. Chronic mucocutaneous candidiasis of late onset, thymoma and myopathy. Clin Experimental Dermatol 1976;1:59–74. [12] Kirkpatrick CH, Windhorst DB. Mucocutaneous candidiasis and thymoma. Am J Med 1979;66:939–45. [13] Stillman MA, Baer RL. Mucocutaneous candidiais and thymoma. JAMA 1973;224:628–9. [14] Ruiz-Argueelles A, Jett JR, Ritts RE. Impaired generation of helper T-cells in a patient with chronic mucocutaneuos candidiasis and malignant thymoma. J Clin Lab Immunol 1983;10:165–9. [15] Sawai T, Tuchikawa K. Kaposi’s sarcoma developed in a patient with a thymoma in the setting of excess numbers of CD8-positive cells in the peripheral blood. Arch Pathol Lab Med 1990;114:611–3. [16] Rowland LP, Griffiths CO, Kabat EA. Myasthenia gravis, thymoma and cryptococcal meningitis. N Engl J Med 1965;273:620–7. [17] Malas D, Weiss S. Progressive Multifocal Leukencephalopathy and Cryptococcal Meningitis with Systemic Lupus Erythematodes and Thymoma. Ann Neurol 1977;1:188–91. ¨ [18] Kirchner T, Muller-Hermelink HK. New Approaches to the diagnosis of thymic epithelial tumors. In: Fenoglio-Preiser CM, Wolff M, Rilke F, editors. Progress in surgical pathology. Philadelphia: Field and Wood Inc., 1989: 167–186.
205
[19] Kirchner T, Schalke B, Marx A, et al. Evaluation of prognostic features in thymic epithelial tumors. Thymus 1989;14:195–203. [20] Kirchner T, Schalke B, Buchwald J, et al. Well-Differentiated Thymic Carcinoma. Am J Surg Pathol 1992;16:1153–69. [21] Blackman M, Kappler J, Marrack P. The role of the T cell receptor in positive and negative selection of developing T cells. Science 1990;248:1335–41. [22] Steinmann GG. Changes in the Human Thymus During Aging. In: ¨ Muller-Hermelink HK, editor. The human thymus. Current topics in pathology. New York: Springer-Verlag, 1986;75:43–88 [23] Melms A, Malcherek G, Gern U, et al. Thymectomy and azathioprine have no effect on the phenotype of CD4 T lymphocyte subsets in myasthenia gravis. J Neurol Neurosurg Psychiatry 1993;56:46– 51. [24] Wijermans HJGH, Oosterhuis HJGH, Astaldi GCB, et al. Influence of adult thymectomy on immunocompetence in patients with myasthenia gravis. J Immunol 1980;124:1977–82. [25] Mackall CL, Granger L, Sheard MA, et al. T-cell regeneration after bone marrow transplantation: differential CD45 isoform expression on thymic-derived versus thymic-independent progeny. Blood 1993;82:2585–94. [26] Lefranc¸ois L, Puddington L. Extrathymic intestinal T-cell development: virtual development? Immunol Today 1995;16:16–21. [27] Schmidt S, Reiter-Owona I, Hotz M, et al. An unusual case of CNS cryptococcosis. J Clin Neurol Neurosurg 1995;97:23–7. [28] Litwin SD, Zanjani ED. Lymphocytes suppressing both immunoglobulin production and erythroid differentiation in hypogammaglobulinaemia. Nature 1977;3:57–8. [29] Levy RM, Bredesen DE, Rosenblum ML. Neurological manifestations of the acquired immunodeficiency syndrome (AIDS): experience at the UCSF and review of the literature. J Neurosurg 1985;62:475–95. [30] Smith DK, Neal JJ, Holmberg SD, et al. Unexplained opportunistic infections and CD41 T-lymphocytopenia without HIV infection. N Engl J Med 1993;328:373–9. [31] Hohlfeld R, Michels M, Heininger K, et al. Azathioprine toxicity during long-term immunosuppression of generalized myasthenia gravis. Neurology 1988;38:258–61. [32] Cadman EC, Durivage HJ. Cancer Chemotherapy. In: Wilson J, Braunwald E, Isselbacher KJ, Petersdorf RG, Martin JB, Fauci AS, Root RK, editors. Harrison’s principles of internal medicine. New York: McGraw-Hill Inc., 1991: 1587–1599. [33] Martin PJ. The role of donor lymphoid cells in allogeneic marrow engraftment. Bone Marrow Transplant 1990;6:283–9.