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Cytologic features of plasmablastic lymphoma
Report of four cases
Article first published online: 31 MAR 2005
Copyright © 2005 American Cancer Society
Volume 105, Issue 3, pages 139–144, 25 June 2005
How to Cite
Lin, O., Gerhard, R., Zerbini, M. C. N. and Teruya-Feldstein, J. (2005), Cytologic features of plasmablastic lymphoma. Cancer, 105: 139–144. doi: 10.1002/cncr.21036
- Issue published online: 13 JUN 2005
- Article first published online: 31 MAR 2005
- Manuscript Revised: 24 JAN 2005
- Manuscript Accepted: 24 JAN 2005
- Manuscript Received: 9 AUG 2004
- human immunodeficiency virus;
Plasmablastic lymphomas (PBLs) were originally described exclusively in human immunodeficiency virus (HIV)-positive patients who presented with jaw or oral mucosa involvement. Recent studies have reported this neoplasm also in patients without HIV infection and involving sites other than head and neck. This lymphoma has a heterogeneous morphologic presentation but distinct phenotype.
Cytologic features from four cases of histologically confirmed PBL were evaluated. The cytology specimens were evaluated for criteria as follow: cellularity, cell size and shape, pleomorphism, cytoplasmic characteristics, chromatin pattern, nucleolar features, and mitotic figures.
Specimens evaluated were two head and neck fine needle aspiration specimens, one anal smear, and one cerebrospinal fluid specimen. Atypical lymphocytes ranged from intermediate to large in size and demonstrated slight nuclear pleomorphism. The cytoplasm varied from scant to moderate in the alcohol-fixed slides. Nuclei were round with vesicular chromatin. Nucleoli varied from a prominent one to multiple small ones. Multinucleated cells and mitotic figures were easily identified in three of four cases. Tingible-body histiocytes were seen in one case. Ancillary studies in two cases demonstrated expression of CD138 with lack of CD20 expression.
PBL is a variant of large cell lymphoma with heterogeneous cytologic findings but distinct immunophenotype. Knowledge of the cytomorphologic spectrum of PBLs and detection of CD138 expression by flow cytometry can be helpful in achieving a correct diagnosis. Cancer (Cancer Cytopathol) 2005. © 2005 American Cancer Society.
Diffuse large B-cell lymphomas (DLBCL) are included in a single category in the World Health Organization (WHO) classification system, but DLBCLs compriset a heterogeneous group of neoplasms with distinct clinical, pathologic, and molecular characteristics. Among the different subtypes of DLBCL, plasmablastic lymphoma (PBL) is a variant that has attracted increased interest. PBL was originally described as a subtype of diffuse large cell lymphoma, presenting almost exclusively in jaw or oral mucosa of human immunodeficiency virus (HIV) infected patients.1 The cells were designated as plasmablastic due to the blastic appearance of neoplastic cells associated with strong expression of plasma cell associated antigens such as CD38 and CD138 and absence or weak expression of B-cell markers. Later studies have reported PBL in patients with and without HIV infection, involving sites other than head and neck and with a heterogeneous morphologic appearance.2–11 The current study analyzes the cytologic features of this unusual lymphoma.
MATERIAL AND METHODS
Cases of large cell lymphomas with absence of B-cell marker expression associated with expression of CD38 and/or CD138 markers were selected from the Memorial Sloan-Kettering Cancer Center and the University of Sao Paulo, School of Medicine files. Only cases with corresponding cytology specimens were included in the current study. The patient population was comprised of 3 HIV-positive males and 1 HIV-negative patient ranging in age from 12 to 40 years. The specimens were represented by two fine needle aspiration (FNA) specimens, one from a submandibular node, and one from a cervical node. Additionally, an anal cytology specimen and a cerebrospinal fluid specimen were analyzed. The primary sites of the lymphoma were mandible (n = 1), anus (n = 1), stomach (n = 1), and cervical lymph node (n = 1). The cytologic features of histologically and immunophenotypically confirmed PBL were evaluated for criteria as follow: cellularity, cell size and shape, pleomorphism, cytoplasm characteristics, nuclear chromatin pattern, nucleolar features, and mitotic figures. The preparations available included direct smears from two cases, FNA and Thinprep® (Cytyc Corporation, Marlborough, MA) specimens. The smears were stained with modified Giemsa and/or Papanicolaou stains, and the Thinprep slides were Papanicolaou stained. The results from the immunocytochemical and flow cytometry studies also were reviewed when available. Immunocytochemical analysis was performed in one case using destained alcohol-fixed slides and subsequently restained immunocytochemically with monoclonal antibodies CD20 (Dako, Carpinteria, CA) and CD3 (Dako, Carpinteria, CA). Immunocytochemical staining enhancement with heat epitope retrieval was performed using a regular vegetable steamer. The sections were placed in a solution of citrate buffer solution (pH 6.0), steamed for 30 minutes, and then cooled before immunocytochemical staining. The antigen–antibody reaction was observed using 3,3′-diaminobenzidine as chromogen. Known positive tissues were used as controls. Flow cytometric evaluation was performed using a dual color technique on a Becton-Dickinson (San Jose, CA) FACScan analyzer. The panel was selected according to the panel of number of cells available. A minimal panel of directly conjugated antibodies was used (CD2, CD3, CD4, CD5, CD8, CD19, CD20, CD38, CD45, kappa, and lambda) to determine the lineage of lymphoid cells. Epstein Barr virus (EBV) (EBNA1) infection was analyzed by immunohistochemistry, in-situ hybridization or polymerase chain reaction (PCR) in the histologic sections of all cases. PCR for the detection of EBV was performed using the protocol described by Shibata et al.12 Immunohistochemical expression of HHV-8 was analyzed in one case.
Abundant atypical lymphocytes were present in three of four cytologic cases. One case (anal cytology specimen) showed the presence of a few atypical lymphocytes in a background of squamous cells. The atypical lymphocytes in all cases ranged in size from intermediate to large, measuring approximately 15–30 μm, with a morphology that ranged from immunoblastic (Fig. 1) to plasmablastic in appearance (Fig. 2). Cytoplasm varied from scant to moderate in the alcohol-fixed slides, and it was evidently more abundant in Quik-Dip® (Mercedes Medical, Sarasota, FL) stained slides (Fig. 2). The plasmacytoid appearance was also more apparent in Quik-Dip® stained slides (Fig. 2). The nuclei were mostly round with vesicular chromatin pattern. Nucleoli varied from a prominent solitary single nucleolus to small multiple nucleoli. Multinucleated cells (Fig. 3) and mitotic figures (Fig 2) were noted in three of four cases. Tingible-body histiocytes were seen in one case (Fig. 4). Immunocytochemistry was performed in the smears of one specimen and was negative for both CD45RO and CD20. Flow cytometry studies performed in this case showed expression of CD10, CD38, CD45, CD56, and cytoplasmic lambda light chain, and absence of expression of CD3, CD4, CD5, CD11C, CD13, CD14, CD16, CD19, CD20, CD23, CD25, CD33, CD34, CD57, CD79a, surface immunoglobulin light chains, myeloperoxidase, and TdT (Fig, 5). Flow cytometry studies performed in another case demonstrated expression of CD45 and absence of expression of CD2, CD3, CD4, CD5, CD8, CD19, CD20, CD38, kappa, and lambda. Immunohistochemical studies were performed in this second case and demonstrated the presence of immunoreactivity for CD138, while immunoreactivity for CD3, CD20, and CD30 were absent. The PBL present in the anus was associated with squamous cell carcinoma in situ and was initially missed in cytologic as well as histologic specimens. Only the squamous cell carcinoma in situ was diagnosed in the initial cytologic evaluation. Histologically, the lymphoma component was initially thought to be a poorly differentiated component of the squamous cell carcinoma, and the correct diagnosis was only obtained with the help of immunohistochemical studies. The lymphoid cells were immunoreactive for CD45 and CD138, while negative for CD20 and cytokeratin. EBV infection was detected in two cases. One case was detected by PCR and one by in-situ hybridization. The two remaining cases were negative by immunohistochemistry (EBV LMP1). HHV-8 immunohistochemical expression was evaluated in one histologic case and was negative.
HIV-positive patients have a higher incidence of hematopoietic malignancies. The most common of these malignancies is high-grade B-cell non-Hodgkin lymphoma, including DLBCL, Burkitt lymphoma, and central nervous system (CNS) lymphoma.13 Delecluse et al. described in 1997 a lymphoma that was thought initially to occur exclusively in the oral cavity of HIV-positive patients.1 Since its original description, there have been several reports and studies of this distinct neoplasm. The concept of these lesions has expanded and now includes lymphomas in patients with and without HIV infection. Involvement of sites other than head and neck and a heterogeneous morphologic appearance have also been described.2–11 Colomo et al. has published the largest series to date (50 cases) of these cases and defined the lesion as a DLBCL with morphologic features and immunophenotypic features indicative of terminal B-cell differentiation and expression of plasma cell associated markers (CD38 and/or CD138).10 The same group identified two major groups of PBL in a series of 50 cases. One was similar to the original description of PBL of the oral cavity by Delecluse et al.,1 in which the cells were mostly blastic in appearance.1 Colomo's group also described a second major group represented by cells with more prominent plasmacytoid appearance, which they designated as PBL with plasmacytic differentiation.
The current study reports cytologic features of four cases of histologically confirmed PBL, which met criteria established by Colomo et al.10 Important clinicopathologic characteristics that underlie our series include: an exclusive predilection to HIV-positive male patients with frequent association to EBV and immunodeficiency, tumor cells that are immunoblastic and/or plasmablastic in appearance with expression of CD138 and absence of CD20 expression. Three cases in our group were better classified into the category of PBL of oral mucosal type as defined by Colomo et al.10 and similar to the original description of Delecluse et al.,1 although one case would be better classified as PBL with plasmacytic differentiation as defined by the Colomo et al.10
Morphologically, differential diagnoses of these tumors include poorly differentiated carcinoma, anaplastic large cell lymphoma, immunoblastic variant of DLBCL, Burkitt lymphoma, primary effusion lymphomas (PEL), and anaplastic plasmacytoma. Poorly differentiated carcinomas enter the differential diagnosis because of prominent nucleoli and high nucleo-cytoplasmic ratio seen in most cases. In fact, in one of the cases, the neoplastic cells were mistaken for a poorly differentiated component of a squamous cell carcinoma that was also present in the same area (collision tumor). Carcinomas can be distinguished from PBLs based on the more frequent cluster formation in carcinomas, larger cell size, absence of lymphoglandular bodies, and presence of immunoreactivity for cytokeratin. CD138 should be used with care because CD138 may be immunoreactive in epithelial neoplasms.14 Anaplastic large cell lymphomas can be considered in the differential diagnosis because of their cell size and presence of multinucleation; however, anaplastic large cell lymphomas are not immunoreactive for CD38 or CD138, whereas PBL is. An immunoblastic variant of DLBCL can be extremely difficult to distinguish from PBL: three of four cases showed the presence of neoplastic lymphoid cells with an immunoblastic appearance. Immunocytochemical or flow cytometric studies are essential to the differential diagnosis. PBLs are negative for CD20, while immunoblastic variants of DLBCLs are negative for CD138. Burkitt lymphoma should be included in the differential diagnosis because cells with multiple small nucleoli, numerous mitotic figures, and occasional tingible-body macrophages are present. As in immunoblastic variants of DLBCL, immunocytochemical and flow cytometric studies play a crucial role in the correct diagnosis. In Burkitt lymphoma, CD20 is immunoreactive and CD138 is negative as opposed to PBLs, which are CD20 negative and immunoeactive for CD138. PEL is a neoplasm that usually presents with serous effusions and without detectable tumor masses. It is usually associated with HIV infection and HHV-8. This unusual tumor shares many immunophenotypic similarities with PBL, such as expression of CD45, CD38, and CD138, while it is negative for CD19, CD20, CD79a, and immunoglobulin expression.15 Morphologically, PELs are usually more pleomorphic and heterogeneous in size than PBLs, with the presence of large anaplastic cells, but the changes may be too subtle for accurate diagnosis.16, 17 The role of HHV-8 in differential diagnosis of extracavitary PEL from HHV-8 is still controversial, as HHV-8 has also been described in PBL by Cioc et al.18 Clinically, the differential diagnosis of extracavitary PEL from PBL may not be crucial because both represent high-grade lymphomas, which can be treated in a similar fashion.
Distinguishing PBL from anaplastic plasmacytoma or myeloma can be the most difficult task, yet the most important for clinical management. Unlike myeloma, computerized tomography and PET scans in patients with PBL usually display extensive bone metastases but not lytic lesions.11 Further, unlike multiple myeloma, PBL has minimal or no IgG M-spike.11 Notably, the proliferative fraction highlighted by MIB-1 is much higher in PBLs (range, 75-100%) compared with anaplastic plasmacytomas (≤ 60%)1 and myelomas (5%) (J. T-F., an author of the current study, personal observation, data not shown). In addition, stains for CD56 and cyclin D1 can be useful because these markers may be positive in plasma cell myelomas and extramedullary plasmacytomas but are negative in PBLs.10 Therefore, combined clinical, morphologic, immunophenotypic, and laboratory data are necessary to distinguish PBL from blastic transformation of a plasma cell neoplasm.
To our knowledge, there are 2 previous case reports describing cytologic findings of a neoplasm with some similarities to the cases in the current study. Stewart et al.19 reported a case of an HIV-positive patient with a mass in the left parotid gland. The FNA of the parotid mass showed large plasmacytoid cells with eccentrically placed nuclei, prominent nucleoli, and abundant basophilic cytoplasm. Immunophenotypically, the cells were immunoreactive for CD38, while negative for CD19, CD20, and CD45.19 Stewart's group favored a diagnosis of anaplastic myeloma because lytic lesions were present. Lin et al.20 described a case of an HIV-negative male who presented with a neck mass. The FNA of the neck mass demonstrated a population of large cells with plasmacytic differentiation, which was immunoreactive for CD 38, CD138, epithelial membrane antigen (EMA), CD30, and lyzozime with presence of EBV by in-situ hybridization.20
PBL is believed to be an aggressive lymphoma. In the original report by Delecluse et al,1 10 of 12 patients with available followup died, nearly all within 12 months of diagnosis. Others have also reported very short survival times.10, 21, 22 However, in the series by Feldstein et al.,11 the median survival appears to be higher than reported by the other authors. The lack of a standard treatment and better HIV management of these patients could account for differences in survival. The median and overall survivals in the series by Feldstein et al. appear to be similar to acquired immunodeficiency syndrome (AIDS)-related lymphoma survival in the highly active antiretroviral therapy (HAART) era reported elsewhere.11, 23, 24
In summary, PBL is a variant of large cell lymphoma with heterogeneous cytologic findings but distinct immunophenotype. Knowledge of the cytomorphologic spectrum of PBL and detection of CD138 expression by flow cytometry can be helpful in achieving a correct diagnosis.
- 24Influence of highly active anti-retroviral therapy on response to treatment and survival in patients with acquired immunodeficiency syndrome-related non-Hodgkin-s lymphoma treated with cyclophosphamide, hydroxydoxorubicin, vincristine and prednisone. Br J Haematol. 2001; 112: 909–915., , , et al.