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Studies of immunoglobulin and T cell receptor gene rearrangement in cutaneous B and T cell lymphomas
Clinical and lahoralor¥ sludies III
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Studies of immunoglobulin and T cell receptor gene rearrangement in cutaneous B and T cell lymphomas Grace Liang, MD," Rube J. Pardo, MD, PhD, b Walter Voigt, PhD, c,d Edwin W. Gould, MD, ° and Vincent Falanga, M D b Miami, Florida We report two patients with cutaneous B and T cell lymphomas, respectively, in which DNA rearrangement studies were instrumental in establishing a diagnosis. In each case clinical, histopathologic, and immunologic criteria were not sufficient to establish a definitive tissue classification. The use of DNA gene rearrangement studies in the analysis of cutaneous lymphomas is discussed. (J AM ACADDERMATOL1989;21:457-60.)
Cutaneous lymphomas usually show distinct growth patterns and may be differentiated by clinical and histologic information. Certain cases, however, may be difficult to diagnose on the basis of morphology alone. Further data may be obtained by immunophenotyping and enzymophenotyping techniques or by electron microscopy. 1,~ More recently, methods using D N A hybridization have proved useful in detecting clonal proliferations of lymphocytes. B lymphocytes contain precise regions of D N A that code for surface-bound immunoglobulins. T tymphocytes have specific regions of D N A that code for membrane-bound receptors, which interact with antigen when the antigen is recognized in conjunction with the major histocompatibility complex. The D N A hybridization technique involves the use of D N A probes specific for these regions of the B and T cell genomes to demonstrate rearrangements of the germ line patterns of DNA. These rearrangements can be used to detect monoclonality of the B or T cell expansions, which is an essential feature of malignancy. These markers may also be used to establish cell lineage and, as tumor-specific markers, to monitor therapy. W e report two patients with cutaneous B and T
From the Departments of Medicine¢ Dermatology and Cutaneous Surgery, b Pathology, ° and the Diagnostic Molecular Biology Laboratory, a University of Miami School of Medicine. Accepted for publication Sept. 7, 1988. Reprint requests: Vincent Falanga, MD, University of Miami School of Medicine, Department of Dermatology and Cutaneous Surgery, P.O. Box 016250 (R-250), Miami, FL 33101.
cell lymphomas in whom histologic studies and immunophenotyping of biopsy specimens were not conclusive. D N A hybridization studies were instrumental in demonstrating gene rearrangements typical of the respective lymphomas. CASE REPORTS
Case 1: Cutaneous B cell lymphoma A 67-year-old white woman had multiple nodular plaques on the left leg that had enlarged during the past 3~ years. She had a history of Hashimoto's thyroiditis, high ANA titers with a nucleolar pattern, and a pericardial effusion of several months' duration. The patient showed sclerodactyly, facial and palmar telangiectasias, edema of the left leg, and multiple indurated, 4 to 5 cm, purple nodules on the pretibial aspect of the left leg (Fig. 1). A complete blood cell count with differential cell count and serum electrolyte determinations yielded normal results. The erythrocyte sedimentation rate was 55 mm/hr (normal 1 to 20 mm/hr). Total serum protein level was 9.3 gin/d1 (normal 6.2 to 8.1 gm/dl), and a serum immunoelectrophoresis showed a polyclonal increase in levels of IgG and IgM. A chest roentgenogram and an echocardiogram showed a large pericardial effusion. No masses or lymph node enlargements were detected on computed tomographic scans of the chest, abdomen, and pelvis. A pericardiocentesis showed an exudative pericardial fluid, but cytologic examination of the fluid did not detect malignant cells. Cultures of the pericardial fluid were negative for bacterial growth. A bone marrow aspirate and biopsy specimen were normal. Skin biopsy specimens of the leg nodules were initially interpreted as having a superficial and deep atypical lymphoreticular infiltrate. Small cells within the infiltrate had an irregular, cleaved morphology, and larger 457
458
Liang et al.
Journal of the American Academy of Dermatology
Fig. 1. Case 1. Purple nodules on pretibial aspect of left leg. Fig. 2. Dense neoplastic lymphoreticular infiltrate composed of irregularly cleaved large and small cells. (x400.) Fig. 3. Case 2. Red nodules widely distributed on body of patient. Fig. 4. Polymorphous infiltrate containing neutrophils, eosinophils, and atypical mononuclear cells separated by edema. (×400.)
cells had large, irregular nuclei. The initial impression was of malignant lymphoma with mixture of large and small cells (Fig. 2). Immunologic phenotype studies were inconclusive. DNA hybridization analysis demonstrated a rearrangement of the joining segment (J.) of the immunoglobulin heavy chain gene, consistent with proliferation of clonal B ceils (see Fig. 5, A). The results of the DNA probe studies established a diagnosis of B cell malignant lymphoma. Case 2: Cutaneous T cell l y m p h o m a A 50-year-old white man with no contributory medical history had multiple painful skin nodules, which had been present for 3 weeks. The lesions were widely distributed, and some were ulcerated (Fig. 3). The patient had tender, diffuse lymphadenopathy, and the penis was swollen and had several ulcerations. Blood cultures and bacterial and viral cultures from the lesions did not grow any organisms. A complete blood cell count showed a slight leukocytosis, but results of serum
electrolyte determinations, urinalysis, and liver function studies were normal. Rapid plasma reagin was nonreactive, and serum test results for human immunodeficiency virus were negative. A computed tomographic scan of the chest, abdomen, and pelvis showed splenomegaly and left axiUary and bilateral inguinal lymphadenopathy. A bone marrow aspirate and biopsy specimen showed panmyeloid hyperplasia with no evidence of malignancy. A cervical lymph node biopsy specimen showed inflammatory granulation tissue with atypical mononuclear cells, suggesting a possible malignant lymphoproliferation. Skin biopsy specimens of several ulcerated nodules on the patient's back had a superficial and deep polymorphous inflammatory infiltrate extending to the epidermis with extensive edema. The infiltrate was composed of neutrophils, eosinophils, and atypical mononuclear cells, some of which appeared convoluted (Fig. 4). This infiltrate was suggestive of, but not diagnostic of, malignant lymphoma. Subsequently the biopsy speei-
Volume 21 Number 3, Part 1 September 1989
Immunoglobulin and T cell receptor gene rearrangement 459
5A
-R
~
12
~
- 5.6
.... R
G
SK
G
G
SK
LN
Fig. 5. Case 1. Autoradiograms of control and skin (SK) tissue. DNA from tissues was digested with a mixture of BamHI/HindlII restriction endonucleases and hybridized with JH probe to joining region of immunoglobulin gene. Germ line (G) position is expressed in kilobases, Tissue shows one germ line band (5.6 kilobases) and two rearranged alleles (R). B, Case 2. Autoradiograms of control, lymph node (LN), and skin (SK) tissue. DNA from tissues was digested with Eco RI restriction endonuclease and hybridized with TcB probe to constant region of the T cell receptor beta chain. Germ line (G) positions are expressed in kilobases. Tissue shows two germ line bands (4.2 and 12.0 kilobases). Gene rearrangement (R) of lymph node and skin are identical. mens of skin and lymph node tissue were studied with DNA hybridization analysis. These studies detected a clonal rearrangement of the T cell receptor gene (see Fig. 5, B), substantiating the clinical and morphologic suspicion of cutaneous T cell lymphoma. DISCUSSION Of extralymphatic organs, the skin ranks second to the stomach in frequency of involvement with malignant lymphomas. Approximately 7.5% of site-specific non-Hodgkin's cell lymphomas are found in the skin? The importance of differentiating cutaneous B cell and T cell lymphomas becomes apparent when one considers the distinct clinical courses, prognosis, and treatment modalities of these tumors? 5 Gene rearrangement analysis has gained recognition as a method to detect clonality of lymphocyte populations.6-8 This relatively new technique has become a sensitive tool to detect clonal B and T cell proliferations of as little as 1% to 5% of a mixed population of cells. 9 This sensitivity is particularly
useful where samples contain small numbers of malignant cells admixed with larger numbers of reactive lymphocytes, or where surface marker studies show a mixture of B and T cells. Indeed, some studies show that T ceils may predominate in certain B cell lymphomas, especially lymphomas of the nodular variety, zo,~l The use of parallel identifications of B and T cell clonal populations now makes it possible to determine precisely the lineage of such lymphomas. Although the D N A hybridization test is sensitive, the gene rearrangements may not be absolutely specific for the respective cell lines. For example, approximately 10% of leukemic T cell populations examined by Arnold et al. n demonstrated immunoglobulin heavy chain gene rearrangements. Likewise, Waldmann et al. n observed a small proportion of leukemic B cells to have clonal beta chain T cell receptor gene rearrangements. In the two patients we have described herein, tissue was analyzed with both immunoglobulin and T cell receptor gene probes. Gene rearrangements
460
Journal of the American Academy of Dermatology
Liang et aL
were detected only in the immunoglobulin gene of the B cell lymphoma and only in the T cell receptor gene of the T cell lymphoma (Fig. 5). D N A probe analysis is also promising as a useful tool for assessing extent of disease and for monitoring therapy. The method's high degree of sensitivity may facilitate early detection of extracutaneous spread, identification of persistent neoplastic ceils, and recurrences after treatment. 9,t4 Another advantage of the gene rearrangement method is its ability to determine B or T cell lineage in the absence of phenotypic markers. This ability was particularly useful to us in the study of patient 1, whose irnmunophenotypic markers were nondiagnostic. Because t h e method does not depend on the functional expression of the immunoglobulin or T celt receptor genes, it can be used to identify clonality in very immature cells or in mature cells in which gene expression is altered. Although the presence of clonality in cutaneous lymphocytic infiltrates provides strong evidence for potential malign.ancy, it cannot always predict the biologic behavior of the disease. For example, clonality was demonstrated in the first patient, but the cutaneous B cell lymphoma remained clinically benign. Indeed, clonal T cell proliferations have been found in lymphomas representing all stages of T cell development, from indolent cases of mycosis fungoides to immature, aggressive lymphoblastic lymphomas? 4,15 Clonal rearrangements are also present in a majority of cases of lymphomatoid papulosis, a disease that histologically resembles malignant lymphoma but that has a chronic and relatively benign clinical course. 16 In conclusion, we have shown that B and T cell gene rearrangement studies may be a valuable adjunct in the study of cutaneous lymphomas. In cases in which the standard histopathologic methods and immunophenotyping and enzymophenotyping techniques are inconclusive, D N A hybridization studies may provide the necessary information to confirm the diagnosis.
REFERENCES
1. Hanno R, Mitchell AJ, Nelson MS, et al. Cutaneous B cell lymphoma:diagnostic use of monoclonal antibodies. J AM ACADDERMATOL1985;13:373-7. 2. Kung PC, Berger CL, Estabrook A, et al. Monoclonal antibodies for clinical investigation of human T lyrnphocytes. Int J Dermatol 1983;22:67-74. 3. Burg G, Kerl H, Przybilla B, ct al. Some statistical data, diagnosis, and staging of cutaneous B cell lymphomas. J Dermatol Surg Oncol 1984;10:256-62. 4. Krishnan J, Li CY, Su WPD. Cutaneous lymphomas: correlation of histochemical and immunohistochemical characteristics and clinieopathologicfeatures. Am J Clin Pathoi 1983;79:157-65. 5. Kerl H, Burg G. Histomorphologyand cytomorphology of cutaneous B cell lymphomas. J Dermatol Surg Oncol 1984;10:266-70. 6. KorsmeyerS J, Arnold A, Bakhshi A, et al. Immunoglobulin gene rearrangement and cell surface antigen expression in acute lymphocyticleukemias of T cell and B cell precursor origins. J Clin Invest 1983;71:301-13. 7. Hedrick SM, Cohen DI, Nielsen EA, et al. Isolation of eDNA clonesencodingT ceil-specificassociatedproteins. Nature 1984;308:14%58. 8. Cleary ML, Chao J, Warnke R, et al. Immunoglobulin gene rearrangement as a diagnostic criterion of B cell lymphoma. Proc Natl Acad Sci USA 1984;81:593-7. 9. Minden MD, Toyonaga B, Ha K, et al. Somatic rearrangements of T cell antigen receptor gene in human T cell malignancies. Proc Nail Aead Sci USA 1985;82:1224-7. 10. AisenbergAC, Krontiris TG, Mak TW, et al. Rearrangement of the gene for the beta chain of the T cell receptor in T cell chronic lymphocytic leukemia and related disorders. N Engl J Med 1985;313:529-33. 11. Willemze R, Meijer CJLM. Analysis of non-neoplastic cells in cutaneous B cell lymphomas. J Dermatol Surg Oncol 1984;10:315-8. 12. ArnoldA, Cossman J, Bakhshi A, et al. Immunoglobulingene rearrangements as unique clonal markers in human lymphoid neoplasms. N Engl J Med 1983;309:1593-9. 13. Waldmann TA, Davis MM, Bongiovanni KF, et al. Rearrangements of genes for the antigen receptor on T cells as markers of lineage and clonality in human lymphoid neoplasms. N Engl J Med 1985;313:776-83. 14. Weiss LM, Hu E, Wood GS, et al. Clonal rearrangements of T cell receptor genes in mycosis fungoides and dermatopathic lymphadenopathy. N Engl J Med 1985; 313:539-44. 15. Bertness V, Kirsch I, Hollis G, et al. T cell receptor gene rearrangements as clinical markers of human T cell lymphomas. N Engl J Med 1985;313:534-8. 16. Weiss LM, Wood GS, Trelan M, et al. Clonal T cell populations in lymphomatoid papulosis. N Engl J Med 1986;315:475-9.
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Studies of immunoglobulin and T cell receptor gene rearrangement in cutaneous B and T cell lymphomas Grace Liang, MD," Rube J. Pardo, MD, PhD, b Walter Voigt, PhD, c,d Edwin W. Gould, MD, ° and Vincent Falanga, M D b Miami, Florida We report two patients with cutaneous B and T cell lymphomas, respectively, in which DNA rearrangement studies were instrumental in establishing a diagnosis. In each case clinical, histopathologic, and immunologic criteria were not sufficient to establish a definitive tissue classification. The use of DNA gene rearrangement studies in the analysis of cutaneous lymphomas is discussed. (J AM ACADDERMATOL1989;21:457-60.)
Cutaneous lymphomas usually show distinct growth patterns and may be differentiated by clinical and histologic information. Certain cases, however, may be difficult to diagnose on the basis of morphology alone. Further data may be obtained by immunophenotyping and enzymophenotyping techniques or by electron microscopy. 1,~ More recently, methods using D N A hybridization have proved useful in detecting clonal proliferations of lymphocytes. B lymphocytes contain precise regions of D N A that code for surface-bound immunoglobulins. T tymphocytes have specific regions of D N A that code for membrane-bound receptors, which interact with antigen when the antigen is recognized in conjunction with the major histocompatibility complex. The D N A hybridization technique involves the use of D N A probes specific for these regions of the B and T cell genomes to demonstrate rearrangements of the germ line patterns of DNA. These rearrangements can be used to detect monoclonality of the B or T cell expansions, which is an essential feature of malignancy. These markers may also be used to establish cell lineage and, as tumor-specific markers, to monitor therapy. W e report two patients with cutaneous B and T
From the Departments of Medicine¢ Dermatology and Cutaneous Surgery, b Pathology, ° and the Diagnostic Molecular Biology Laboratory, a University of Miami School of Medicine. Accepted for publication Sept. 7, 1988. Reprint requests: Vincent Falanga, MD, University of Miami School of Medicine, Department of Dermatology and Cutaneous Surgery, P.O. Box 016250 (R-250), Miami, FL 33101.
cell lymphomas in whom histologic studies and immunophenotyping of biopsy specimens were not conclusive. D N A hybridization studies were instrumental in demonstrating gene rearrangements typical of the respective lymphomas. CASE REPORTS
Case 1: Cutaneous B cell lymphoma A 67-year-old white woman had multiple nodular plaques on the left leg that had enlarged during the past 3~ years. She had a history of Hashimoto's thyroiditis, high ANA titers with a nucleolar pattern, and a pericardial effusion of several months' duration. The patient showed sclerodactyly, facial and palmar telangiectasias, edema of the left leg, and multiple indurated, 4 to 5 cm, purple nodules on the pretibial aspect of the left leg (Fig. 1). A complete blood cell count with differential cell count and serum electrolyte determinations yielded normal results. The erythrocyte sedimentation rate was 55 mm/hr (normal 1 to 20 mm/hr). Total serum protein level was 9.3 gin/d1 (normal 6.2 to 8.1 gm/dl), and a serum immunoelectrophoresis showed a polyclonal increase in levels of IgG and IgM. A chest roentgenogram and an echocardiogram showed a large pericardial effusion. No masses or lymph node enlargements were detected on computed tomographic scans of the chest, abdomen, and pelvis. A pericardiocentesis showed an exudative pericardial fluid, but cytologic examination of the fluid did not detect malignant cells. Cultures of the pericardial fluid were negative for bacterial growth. A bone marrow aspirate and biopsy specimen were normal. Skin biopsy specimens of the leg nodules were initially interpreted as having a superficial and deep atypical lymphoreticular infiltrate. Small cells within the infiltrate had an irregular, cleaved morphology, and larger 457
458
Liang et al.
Journal of the American Academy of Dermatology
Fig. 1. Case 1. Purple nodules on pretibial aspect of left leg. Fig. 2. Dense neoplastic lymphoreticular infiltrate composed of irregularly cleaved large and small cells. (x400.) Fig. 3. Case 2. Red nodules widely distributed on body of patient. Fig. 4. Polymorphous infiltrate containing neutrophils, eosinophils, and atypical mononuclear cells separated by edema. (×400.)
cells had large, irregular nuclei. The initial impression was of malignant lymphoma with mixture of large and small cells (Fig. 2). Immunologic phenotype studies were inconclusive. DNA hybridization analysis demonstrated a rearrangement of the joining segment (J.) of the immunoglobulin heavy chain gene, consistent with proliferation of clonal B ceils (see Fig. 5, A). The results of the DNA probe studies established a diagnosis of B cell malignant lymphoma. Case 2: Cutaneous T cell l y m p h o m a A 50-year-old white man with no contributory medical history had multiple painful skin nodules, which had been present for 3 weeks. The lesions were widely distributed, and some were ulcerated (Fig. 3). The patient had tender, diffuse lymphadenopathy, and the penis was swollen and had several ulcerations. Blood cultures and bacterial and viral cultures from the lesions did not grow any organisms. A complete blood cell count showed a slight leukocytosis, but results of serum
electrolyte determinations, urinalysis, and liver function studies were normal. Rapid plasma reagin was nonreactive, and serum test results for human immunodeficiency virus were negative. A computed tomographic scan of the chest, abdomen, and pelvis showed splenomegaly and left axiUary and bilateral inguinal lymphadenopathy. A bone marrow aspirate and biopsy specimen showed panmyeloid hyperplasia with no evidence of malignancy. A cervical lymph node biopsy specimen showed inflammatory granulation tissue with atypical mononuclear cells, suggesting a possible malignant lymphoproliferation. Skin biopsy specimens of several ulcerated nodules on the patient's back had a superficial and deep polymorphous inflammatory infiltrate extending to the epidermis with extensive edema. The infiltrate was composed of neutrophils, eosinophils, and atypical mononuclear cells, some of which appeared convoluted (Fig. 4). This infiltrate was suggestive of, but not diagnostic of, malignant lymphoma. Subsequently the biopsy speei-
Volume 21 Number 3, Part 1 September 1989
Immunoglobulin and T cell receptor gene rearrangement 459
5A
-R
~
12
~
- 5.6
.... R
G
SK
G
G
SK
LN
Fig. 5. Case 1. Autoradiograms of control and skin (SK) tissue. DNA from tissues was digested with a mixture of BamHI/HindlII restriction endonucleases and hybridized with JH probe to joining region of immunoglobulin gene. Germ line (G) position is expressed in kilobases, Tissue shows one germ line band (5.6 kilobases) and two rearranged alleles (R). B, Case 2. Autoradiograms of control, lymph node (LN), and skin (SK) tissue. DNA from tissues was digested with Eco RI restriction endonuclease and hybridized with TcB probe to constant region of the T cell receptor beta chain. Germ line (G) positions are expressed in kilobases. Tissue shows two germ line bands (4.2 and 12.0 kilobases). Gene rearrangement (R) of lymph node and skin are identical. mens of skin and lymph node tissue were studied with DNA hybridization analysis. These studies detected a clonal rearrangement of the T cell receptor gene (see Fig. 5, B), substantiating the clinical and morphologic suspicion of cutaneous T cell lymphoma. DISCUSSION Of extralymphatic organs, the skin ranks second to the stomach in frequency of involvement with malignant lymphomas. Approximately 7.5% of site-specific non-Hodgkin's cell lymphomas are found in the skin? The importance of differentiating cutaneous B cell and T cell lymphomas becomes apparent when one considers the distinct clinical courses, prognosis, and treatment modalities of these tumors? 5 Gene rearrangement analysis has gained recognition as a method to detect clonality of lymphocyte populations.6-8 This relatively new technique has become a sensitive tool to detect clonal B and T cell proliferations of as little as 1% to 5% of a mixed population of cells. 9 This sensitivity is particularly
useful where samples contain small numbers of malignant cells admixed with larger numbers of reactive lymphocytes, or where surface marker studies show a mixture of B and T cells. Indeed, some studies show that T ceils may predominate in certain B cell lymphomas, especially lymphomas of the nodular variety, zo,~l The use of parallel identifications of B and T cell clonal populations now makes it possible to determine precisely the lineage of such lymphomas. Although the D N A hybridization test is sensitive, the gene rearrangements may not be absolutely specific for the respective cell lines. For example, approximately 10% of leukemic T cell populations examined by Arnold et al. n demonstrated immunoglobulin heavy chain gene rearrangements. Likewise, Waldmann et al. n observed a small proportion of leukemic B cells to have clonal beta chain T cell receptor gene rearrangements. In the two patients we have described herein, tissue was analyzed with both immunoglobulin and T cell receptor gene probes. Gene rearrangements
460
Journal of the American Academy of Dermatology
Liang et aL
were detected only in the immunoglobulin gene of the B cell lymphoma and only in the T cell receptor gene of the T cell lymphoma (Fig. 5). D N A probe analysis is also promising as a useful tool for assessing extent of disease and for monitoring therapy. The method's high degree of sensitivity may facilitate early detection of extracutaneous spread, identification of persistent neoplastic ceils, and recurrences after treatment. 9,t4 Another advantage of the gene rearrangement method is its ability to determine B or T cell lineage in the absence of phenotypic markers. This ability was particularly useful to us in the study of patient 1, whose irnmunophenotypic markers were nondiagnostic. Because t h e method does not depend on the functional expression of the immunoglobulin or T celt receptor genes, it can be used to identify clonality in very immature cells or in mature cells in which gene expression is altered. Although the presence of clonality in cutaneous lymphocytic infiltrates provides strong evidence for potential malign.ancy, it cannot always predict the biologic behavior of the disease. For example, clonality was demonstrated in the first patient, but the cutaneous B cell lymphoma remained clinically benign. Indeed, clonal T cell proliferations have been found in lymphomas representing all stages of T cell development, from indolent cases of mycosis fungoides to immature, aggressive lymphoblastic lymphomas? 4,15 Clonal rearrangements are also present in a majority of cases of lymphomatoid papulosis, a disease that histologically resembles malignant lymphoma but that has a chronic and relatively benign clinical course. 16 In conclusion, we have shown that B and T cell gene rearrangement studies may be a valuable adjunct in the study of cutaneous lymphomas. In cases in which the standard histopathologic methods and immunophenotyping and enzymophenotyping techniques are inconclusive, D N A hybridization studies may provide the necessary information to confirm the diagnosis.
REFERENCES
1. Hanno R, Mitchell AJ, Nelson MS, et al. Cutaneous B cell lymphoma:diagnostic use of monoclonal antibodies. J AM ACADDERMATOL1985;13:373-7. 2. Kung PC, Berger CL, Estabrook A, et al. Monoclonal antibodies for clinical investigation of human T lyrnphocytes. Int J Dermatol 1983;22:67-74. 3. Burg G, Kerl H, Przybilla B, ct al. Some statistical data, diagnosis, and staging of cutaneous B cell lymphomas. J Dermatol Surg Oncol 1984;10:256-62. 4. Krishnan J, Li CY, Su WPD. Cutaneous lymphomas: correlation of histochemical and immunohistochemical characteristics and clinieopathologicfeatures. Am J Clin Pathoi 1983;79:157-65. 5. Kerl H, Burg G. Histomorphologyand cytomorphology of cutaneous B cell lymphomas. J Dermatol Surg Oncol 1984;10:266-70. 6. KorsmeyerS J, Arnold A, Bakhshi A, et al. Immunoglobulin gene rearrangement and cell surface antigen expression in acute lymphocyticleukemias of T cell and B cell precursor origins. J Clin Invest 1983;71:301-13. 7. Hedrick SM, Cohen DI, Nielsen EA, et al. Isolation of eDNA clonesencodingT ceil-specificassociatedproteins. Nature 1984;308:14%58. 8. Cleary ML, Chao J, Warnke R, et al. Immunoglobulin gene rearrangement as a diagnostic criterion of B cell lymphoma. Proc Natl Acad Sci USA 1984;81:593-7. 9. Minden MD, Toyonaga B, Ha K, et al. Somatic rearrangements of T cell antigen receptor gene in human T cell malignancies. Proc Nail Aead Sci USA 1985;82:1224-7. 10. AisenbergAC, Krontiris TG, Mak TW, et al. Rearrangement of the gene for the beta chain of the T cell receptor in T cell chronic lymphocytic leukemia and related disorders. N Engl J Med 1985;313:529-33. 11. Willemze R, Meijer CJLM. Analysis of non-neoplastic cells in cutaneous B cell lymphomas. J Dermatol Surg Oncol 1984;10:315-8. 12. ArnoldA, Cossman J, Bakhshi A, et al. Immunoglobulingene rearrangements as unique clonal markers in human lymphoid neoplasms. N Engl J Med 1983;309:1593-9. 13. Waldmann TA, Davis MM, Bongiovanni KF, et al. Rearrangements of genes for the antigen receptor on T cells as markers of lineage and clonality in human lymphoid neoplasms. N Engl J Med 1985;313:776-83. 14. Weiss LM, Hu E, Wood GS, et al. Clonal rearrangements of T cell receptor genes in mycosis fungoides and dermatopathic lymphadenopathy. N Engl J Med 1985; 313:539-44. 15. Bertness V, Kirsch I, Hollis G, et al. T cell receptor gene rearrangements as clinical markers of human T cell lymphomas. N Engl J Med 1985;313:534-8. 16. Weiss LM, Wood GS, Trelan M, et al. Clonal T cell populations in lymphomatoid papulosis. N Engl J Med 1986;315:475-9.