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Journal Reading. 2006-05-05 Presented by Dr. 陳志榮. ALK-Positive Anaplastic Large Cell Lymphoma Mimicking Nodular Sclerosis Hodgkin ’ s Lymphoma Report of 10 Cases. Jose´ Vassallo, MD, PhD,*† Laurence Lamant, MD, PhD,* Laurence Brugieres, MD, PhD,‡
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Journal Reading 2006-05-05 Presented by Dr.陳志榮
ALK-Positive Anaplastic Large Cell Lymphoma MimickingNodular Sclerosis Hodgkin’s LymphomaReport of 10 Cases Jose´ Vassallo, MD, PhD,*† Laurence Lamant, MD, PhD,* Laurence Brugieres, MD, PhD,‡ Fanny Gaillard, MD, PhD,§ Elias Campo, MD, PhD,k Pierre Brousset, MD, PhD,* and Georges Delsol, MD* ~~Am J Surg Pathol 2006;30:223–229
INTRODUCTION • Anaplastic large cell lymphoma (ALCL) and Hodgkin lymphoma (HL): (1) biologically distinct entities. (2) share some morphologic features. • In 10 years, 380 cases of ALK-positive ALCL (1) 10 cases: originally diagnosed as nodular sclerosis classic HL (NSHL) on conventional histopathological examination.
INTRODUCTION • Anaplastic large cell lymphoma (ALCL) (1) first described as a distinct type of non -Hodgkin lymphoma in 1985. (2) characterized by the expression of the CD30 antigen. (3) large cell non-Hodgkin lymphomas, malignant histiocytosis, and Hodgkin lymphoma (HL). (4) approximately 3% to 5% of non-Hodgkin lymphomas in adults and 10% to 30% in children.
INTRODUCTION • REAL and the WHO classification, recognized only ALCL of T/null cell phenotype as a distinct entity. (1) large cells with anaplastic morphologic features, expressing the CD30 antigen. (2) a clear B-cell phenotype were included in the broad group of diffuse large B-cell lymphomas. • REAL classification: ‘‘ALCL Hodgkin-like’’ or ‘‘Hodgkin related’’ to take into consideration the existence of cases with intermediate morphologic and phenotypical features between ALCL and HL.
INTRODUCTION • ALK1 antibody: confirmed that ALCL and HL are clinically and biologically different entities. • ALCL is a T/null cell neoplasm, positive for cytotoxic markers, such as TIA1, granzyme B, and perforin, but negative for EBV. • About 60% to 80% of ALCLs express the NPM-ALK protein resulting in the t (2;5), which is absent in HL. • WHO classification: three histologic variants of ALCL (common, lymphohistiocytic, and small cell variants) and does not include a ‘‘Hodgkin-like variant’’ ALCL.
INTRODUCTION • grey-zone lymphomas (1) HL with some features reminiscent of ALCL. (2) the syncytial variant of nodular sclerosis => fibrosis is evident and neoplastic cells are present in large sheets.
MATERIALS AND METHODS • 10 ALCL with Hodgkin-like features in the Laboratory of Pathology of the Hoˆ pital Purpan, University of Toulouse, Toulouse, France • CD20, Pax5/BSAP (BD Biosiences), CD3, CD15, CD30, CD43, EMA, ALK protein, perforin,BNH-9 (GD), and the latent membrane protein 1 of the Epstein-Barr virus (LMP1/EBV, clone CS1-4, Dako). • In 7 cases with available paraffin blocks, additional T-cell markers, namely, CD2, CD4, CD5, CD7, and CD8, were tested. • In 6 cases, in situ hybridization for EBV using the EBER probe (Dako) was also available.
RESULTS • Among 380 cases diagnosed as ALK-positive ALCL, 10 were considered to be good examples of Hodgkin-like ALCL (2.6%).
Histopathology • Intense capsular fibrosis forming cellular nodules delimited by thick fibrous bands: all cases (except one) • Morphology is variable: most of them were mononucleated, with moderate to abundant eosinophilic cytoplasm. • Nucleus : round, oval- or kidney-shaped, with more or less coarse chromatin and small- to medium-sized nucleoli. • Binucleated neoplastic cells with prominent nucleoli reminiscent of Reed-Sternberg cells were observed in variable numbers: all cases
Histopathology • 5 cases: mummified cells were seen and in two rare lacunar-like cells. • Sinus involvement: all cases but mostly focal. • 6 cases: neoplastic atypical cells were scattered in a cellular background consisting of lymphocytes and plasma cells, or formed small nests. • 4 cases: sheets of cohesive neoplastic cells were present.
Histopathology • Hallmark cells. • 4 cases: moderate to prominent perivascular pattern of neoplastic cells. • Residual germinal centers were prominent in 5 cases, scarce in 1, and absent in 4 cases. • Small lymphocytes predominated in the background in all case. • Eosinophils and neutrophils were present in moderate numbers in only 1 case. • Histiocytes were also present in variable numbers, no epithelioid granulomas.
Immunohistochemical Findings • 7 cases: overall T-cell phenotype of neoplastic cells • 3 cases: null/undetermined phenotype. • 6 cases: CD43 was expressed by neoplastic cells. • 6 cases: BNH-9 antibody strongly positive in 3 and focally in 1. • 8 cases: LMP1/EBV was not detected in neoplastic cell => confirmed by in situ hybridization technique using the EBER probe in 6 cases.
DISCUSSION • There was no definite criteria for differentiating ALCL from HL before the availability of ALK1 antibody =>‘‘Hodgkin-related’’ or ‘‘Hodgkin’s-like’’ALCL • Orscheschek et al : suggested that HL and ALCL were closely related because they were able to demonstrate t(2;5) in about 70% to 80% of HL. • These results have not been confirmed by multiple studies using a variety of techniques. • It is now largely recognized that ALCL and HL are distinct entities and, despite that there may be morphologic overlap between ALCL and HL, there is no true biologic borderline.
DISCUSSION • The present study further demonstrates the existence of rare cases of ALK-positive ALCL resembling HL, and some of these cases were diagnosed as HL by expert hematopathologists on morphologic ground alone. • In effect, all these cases showed lymph node features suggesting NSHL, namely, nodular fibrosis associated with capsular thickening and tumor cells resembling Reed-Sternberg cells. • In addition, these cases contained sheets of atypical cells as seen in NSHL associated with scattered atypical cells further accentuating the resemblance to HL, including the presence of some lacunar-like cells and mummified cells (5 of our cases).
DISCUSSION • The detection of atypical cells within residual lymphatic sinuses seen in all cases is characteristically observed in ALCL but may occasionally be observed in HL (about 5% of our cases) • Some ‘‘hallmark cells’’ were observed but were rather scarce, and the predominant cell population consisted of large mononuclear cells without specific morphologic features.
DISCUSSION • These cases were categorized correctly only after immunostaining: (1)Atypical cells were positive for ALK protein=>cytoplasmic, nuclear, and nucleolar staining pattern. (2) 1 case suggests an association with the t(2;5) and the expression of NPM-ALK protein.
DISCUSSION • 3 cases: large cells were scattered among a predominant population of ALK-positive small cells associated with non-neoplastic small lymphocytes. • The detection of a perivascular pattern, which was obvious in 4 cases, supports such a hypothesis because this finding has been reported as a frequent feature in the ‘‘small cell variant’’ ALCL but has not been noted in HL.
DISCUSSION • Tumor cells were strongly positive for CD30 and EMA but negative for CD15 antigen. • CD15: (1) about 75% of HL, (2) may be occasionally found in rare cases of ALK-positive ALCL. =>these cases did not resemble HL, and the staining was restricted to the paranuclear area.
DISCUSSION • EMA: (1) observed in the majority of ALCL =>3 cases only a proportion of malignant cell were positive. (2) weak staining: about 5% of HL. (3) such a positive staining in a given case should question the diagnosis of HL and require additional stainings, namely, ALK and T-cell markers.
DISCUSSION • Overall, T-cell phenotype of neoplastic cells was confirmed in 7 cases, but only 4 cases were positive for CD3, which is in agreement with previous studies on ALCL, because only one fourth of ALCL expressed this antigen. • CD3: may be positive in rare cases of HL, but the staining is usually cytoplasmic (dotlike staining).
DISCUSSION • As previously reported in ALCL, 4 cases of the present series were positive for other T-cell markers (CD2, CD4, CD5, and/or CD7) and perforin. • CD4: has been reported in RS, but convincing staining is very rare and all other T-cell markers, particularly perforin, are not expressed by RS cell.
DISCUSSION • Most of our cases (6 of 9 cases) were positive for CD43. (1) this antigen is expressed by the majority of ALCL and, before the availability of ALK1 antibody. (2) CD43 was a useful marker in the differential diagnosis between ALCL and HL, because it is reported positive in only 5% of HL. • The cases of the present study were negative for EBV. => ALCL is not an EBV-associated disease (1) immunohistochemistry (LMP1) (2) in situ hybridization (EBER probe)
DISCUSSION • Consequently, we think that lesions showing morphologic features of NSHL, with or without sinusoidal growth pattern, but negative for CD15, should not be diagnosed as Hodgkin-like ALCL unless they are positive for ALK • If they are negative for ALK protein, these lesions deserve additional immunostaining, including Pax5 and several T-cell markers and PCR to look for a clonal T-cell population to rule out an atypical T-cell non-Hodgkin lymphoma (eg, nodal cytotoxic T-cell lymphoma). • If they are negative for T-cell markers and for PCR, these lesions should be considered as HL and treated as such.
DISCUSSION • Our results support the need of recognition of a Hodgkin-like morphologic variant of ALCL, not to suggest a relationship between the two entities but to alert the surgical pathologist to systematically include in the first line panel of antibody anti-EMA and, if positive, to ask for ALK staining.