Hematopathology Diagnoses Too Easy to Miss!
Recognition and Classification of Malignant Lymphomas
Marsha Kinney, James Cook and Steven Swerdlow
Classification of malignant lymphomas and the avoidance of errors: The first step in avoiding the pitfalls of diagnostic hematopathology is to know your
options. This means knowing the specific benign entities that we diagnose including those that
mimic lymphomas and being aware of the long list of lymphomas that we are now required to recognize and
diagnose. Even if one doesn't master the entire list (a fate left to a very few), one can manage by
being extra careful when a lymphoid proliferation doesn't fit well into one of the entities that you do
know about. In terms of the long list of lymphomas to master, at least in 2009, there is an
internationally agreed upon classification with a just recently published well-illustrated monograph to
use – the 2008 revision of the 2001 WHO classification of the haematopoietic and lymphoid
tumours.  This monograph essentially includes much of what was included in the update of
cutaneous lymphomas that were published in the 2005 WHO/EORTC consensus classification for cutaneous
The 2008 World Health Organization classification recognizes a list of distinct clinicopathologic
entities agreed upon not only by hematopathologists but also by a clinical advisory group of
hematologists/oncologists. The WHO classification, divides lymphomas into those of non-Hodgkin and
Hodgkin type and then divides the precursor and mature non-Hodgkin lymphomas into those of B-cell or
T-cell (or natural killer cell) origin, similar to the original "functional" Lukes/Collins and Kiel
classifications from more than three decades ago.
2008 WHO Classification of lymphoid neoplasms
PRECURSOR LYMPHOID NEOPLASMS|
B lymphoblastic leukaemia/lymphoma
B lymphoblastic leukaemia/lymphoma, NOS
B lymphoblastic leukaemia/lymphoma with recurrent genetic abnormalities
B lymphoblastic leukaemia/lymphoma with t(9;22)(q34;q11.2); BCR-ABL1
B lymphoblastic leukaemia/lymphoma with t(v;11q23); MLL rearranged
B lymphoblastic leukaemia/lymphoma with t(12;21)(p13;q22); TEL-AML1(ETV6-RUNX1)
B lymphoblastic leukaemia/lymphoma with hyperdiploidy
B lymphoblastic leukaemia/lymphoma with hypodiploidy (hypodiploid ALL)
B lymphoblastic leukaemia/lymphoma with t(5;14)(q31;q32); IL3-IGH
B lymphoblastic leukaemia/lymphoma with t(1;19)(q23;p13.3); E2A-PBX1;
T lymphoblastic leukaemia/lymphoma
MATURE B-CELL NEOPLASMS
Chronic lymphocytic leukaemia/small lymphocytic lymphoma
B-cell prolymphocytic leukaemia
Splenic marginal zone lymphoma
Hairy cell leukaemia
Splenic lymphoma/leukaemia, unclassifiable
Splenic diffuse red pulp small B-cell lymphoma
Hairy cell leukaemia-variant
Heavy chain diseases
Alpha heavy chain disease
Gamma heavy chain disease
Mu heavy chain disease
Plasma cell myeloma
Solitary plasmacytoma of bone
Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) Nodal marginal
Paediatric nodal marginal zone lymphoma
Paediatric follicular lymphoma
Primary cutaneous follicle centre lymphoma
Mantle cell lymphoma
Diffuse large B-cell lymphoma (DLBCL), NOS
T-cell/histiocyte rich large B-cell lymphoma
Primary DLBCL of the CNS
Primary cutaneous DLBCL, leg type
EBV positive DLBCL of the elderly
DLBCL associated with chronic inflammation
Primary mediastinal (thymic) large B-cell lymphoma
Intravascular large B-cell lymphoma
ALK positive DLBCL
Large B-cell lymphoma arising in HHV8-associated multicentric Castleman disease
Primary effusion lymphoma
B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma and
B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma and
classical Hodgkin lymphoma
MATURE T-CELL AND NK-CELL NEOPLASMS
T-cell prolymphocytic leukaemia
T-cell large granular lymphocytic leukaemia
Chronic lymphoproliferative disorder of NK-cells
Aggressive NK cell leukaemia
Systemic EBV positive T-cell lymphoproliferative disease of childhood
Hydroa vacciniforme-like lymphoma
Adult T-cell leukaemia/lymphoma
Extranodal NK/T cell lymphoma, nasal type
Enteropathy-associated T-cell lymphoma
Hepatosplenic T-cell lymphoma
Subcutaneous panniculitis-like T-cell lymphoma
Primary cutaneous CD30 positive T-cell lymphoproliferative disorders
Primary cutaneous anaplastic large cell lymphoma
Primary cutaneous gamma-delta T-cell lymphoma
Primary cutaneous CD8 positive aggressive epidermotropic cytotoxic T-cell
Primary cutaneous CD4 positive small/medium T-cell lymphoma
Peripheral T-cell lymphoma, NOS
Angioimmunoblastic T-cell lymphoma
Anaplastic large cell lymphoma, ALK positive
Anaplastic large cell lymphoma, ALK negative
Nodular lymphocyte predominant Hodgkin lymphoma
Classical Hodgkin lymphoma
Nodular sclerosis classical Hodgkin lymphoma
Lymphocyte-rich classical Hodgkin lymphoma
Mixed cellularity classical Hodgkin lymphoma
Lymphocyte depleted classical Hodgkin lymphoma
POST-TRANSPLANT LYMPHOPROLIFERATIVE DISORDERS (PTLD)
Infectious mononucleosis-like PTLD
Monomorphic PTLD (B- and T/NK-cell types)*
Classical Hodgkin lymphoma type PTLD*
NOS, not otherwise specified.
The italicized histologic types are provisional entities, for which the WHO Working Group felt there
was insufficient evidence to recognize as distinct diseases at this time.
*These lesions are classified according to the disease entity to which they correspond.
The second step in avoiding errors is know to how to use histopathology together
with a variety of ancillary tools to make the diagnoses that you now know exist . Learning how to
judiciously use and wisely interpret the host of special studies that are a part of diagnostic
hematopathology are just as critical as knowing the basic criteria for the hematopoietic/lymphoid
disorders. Histopathology remains the most important element in evaluating diagnostic lymph node
biopsies and extranodal hematopoietic/lymphoid proliferations even in 2009. It is far beyond the scope
of this course to discuss the role of cytopathology in these circumstances. The cases that will be
presented were hard enough even with entire tissue biopsies available. Immunophenotypic studies,
whether performed using flow cytometric and/or immunohistochemical methods are only a photo-finish behind
morphologic studies in terms of being essential in most cases that we deal with today. It is an
acknowledged challenge knowing what methods to use in which circumstances and dealing with the growing
list of antibodies that we have at our disposal. Once again, it is beyond the scope of this course to
discuss this topic in general; however, you will see how important immunohistochemical studies were in
the cases we will be reviewing today. Cytogenetic studies, essentially required in the diagnosis of
acute leukemias, have been utilized much less in dealing with lymphoid disorders. However, they are
gaining in both popularity and importance for several reasons. Classical cytogenetic studies (G-banded
karyotypes) are used in some institutions for the work-up of lymphomas, even though they are labor
intensive and therefore not inexpensive to perform. While not infrequently contributing supportive
information to well-worked up cases or providing information that may have prognostic implications, the
number of cases where classical cytogenetic studies provide information directly leading to a diagnosis
that might otherwise have been missed is very few.  Furthermore, there are rare occasions
where these studies can be misleading with evidence of a cytogenetic clone in the absence of a
recognizable lymphoma. Cytogenetic molecular fluorescence in situ hybridization (ô ) studies, on the
other hand, do not require fresh cells and are increasingly popular since they can be performed using
cells in paraffin sections or extracted from paraffin blocks if metaphase or interphase cells in
cytogenetic preparations or interphase cells on touch imprints are not available. In addition, there are
increasing numbers of commercially available probes to look for many of the chromosomal abnormalities
that characterize specific types of lymphomas or have prognostic implications.
there are molecular genetic studies, using Southern blot or polymerase chain reaction (PCR) analysis.
These studies, also fraught with many hazards, can be critical; however, they are unnecessary in most
cases at the current time. They may provide false negative and false positive results. The availability
of the "Biomed-2" primers for PCR studies looking for evidence of clonal B-cell or T-cell proliferations
may help improve this situation and have been reported to be superior to Southern blot
Remember, however, that just because a test is more sophisticated, it does not
necessarily provide a more correct answer. Gene expression profiling is another type of molecular
testing that is being used to study lymphomas (and other types of proliferations); however, it is not
ready for routine use in diagnostic hematopathology.
The third step in giving yourself the best chance at arriving at the correct
diagnosis is to use all the information you can lay your hands on including the clinical and other
laboratory data. Having an up-to-date list of diagnostic options and knowing or having access to
their diagnostic criteria, personally selecting and then integrating the data from all of the above
studies, and then educating yourself as much as you can about the patient's clinical and laboratory
findings will give you the best chance of staying out of trouble and turn you into a star!
- Swerdlow SH, Campo E, Harris NL, et al. WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues. IARC: Lyon 2008.
- Burg G, Kempf W, Cozzio A, et al. WHO/EORTC classification of cutaneous lymphomas 2005: histological and molecular aspects. J Cutan Pathol 32: 647-674, 2005.
- LeBoit PE, Burg G, Weedon D, et al. Pathology and Genetics of Skin Tumours. IARC Press: Lyon 2006.
- Willemze R, Jaffe ES, Burg G, et al. WHO-EORTC classification for cutaneous lymphomas. Blood 105: 3768-3785, 2005.
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- van Dongen JJ, Langerak AW, Bruggemann M, et al. Design and standardization of PCR primers and protocols for detection of clonal immunoglobulin and T-cell receptor gene recombinations in suspect lymphoproliferations: report of the BIOMED-2 Concerted Action BMH4-CT98-3936. Leukemia 17: 2257-2317, 2003.
- Sandberg Y, van Gastel-Mol EJ, Verhaaf B, et al. BIOMED-2 multiplex immunoglobulin/T-cell receptor polymerase chain reaction protocols can reliably replace Southern blot analysis in routine clonality diagnostics. J Mol Diagn 7: 495-503, 2005.
- Evans PA, Pott C, Groenen PJ, et al. Significantly improved PCR-based clonality testing in B-cell malignancies by use of multiple immunoglobulin gene targets. Report of the BIOMED-2 Concerted Action BHM4-CT98-3936. Leukemia, 2006.
- Wiestner A, Staudt LM. Towards molecular diagnosis and targeted therapy of lymphoid malignancies. Semin Hematol 40: 296-307, 2003.
- Staudt LM. Molecular Diagnosis of the Hematologic Cancers. N Engl J Med 348: 1777-1785, 2003.