Name

Primary mediastinal (thymic) large B-cell lymphoma

ICD-O-3 Morphology

9679/3: Mediastinal large B-cell lymphoma
Effective 2001 and later

Reportable

for cases diagnosed 2001 and later

Primary Site(s)

C379, C383
Do not assign this histology just because the mediastinum is involved. Only assign this histology when the diagnosis is stated as “primary mediastinal."

Grade

Not Applicable

Module Rule

None

Alternate Names

Med-DLBCL
Mediastinal large B-cell lymphoma
Mediastinal diffuse large cell lymphoma with sclerosis
PMBL
Primary mediastinal clear cell lymphoma of B-cell type [OBS]
Thymic large B-cell lymphoma

Definition

Primary mediastinal (thymic) large B-cell lymphoma (PMBL) is a mature aggressive large B-cell lymphoma (LBCL) of putative thymic B-cell origin arising in the mediastinum, with distinctive clinical, immunophenotypic, genotypic, and molecular features. Cases that arise outside the mediastinum are probably very uncommon, and cannot be confidently recognized without gene expression profiling studies.

Abstractor Notes

Code the primary site to C379 (thymus) or C383 (mediastinum) based on the physician's statement. For either thymus or mediastinal primaries, the mediastinal and cervical lymph nodes may be involved.

PMBL most likely arises within the thymus. Patients present with a localized anterosuperior mediastinal mass. The mass is often bulky and frequently invades adjacent structures such as lungs, pleura, or pericardium. Spread to supraclavicular and cervical LN can occur.

Workup should be done to exclude a secondary mediastinal involvement by a DLBCL versus a primary mediastinal B-cell lymphoma through the absence of bone marrow involvement and lymph node involvement outside of the region.

Definitive Diagnostic Methods

Genetic testing
Histologic confirmation
Immunophenotyping

Genetics Data

CIITA at 16p13.13
Immunoglobulin genes clonally rearranged
PDCD1LG1 (also called CF274 or PDL1)
PDCD1LG2 (also called PDL2)
9p24.1

Immunophenotyping

BOB1 expression
CD19 expression
CD20 expression
CD22 expression
CD30 weakly positive and heterogeneous
CD79a expression
Ig functional gene arrangement
Immunoglobulin lacking
OCT2 expression
PAX5 expression
PU1 expression

Treatments

Chemotherapy
Radiation therapy

Transformations to

There are no known transformations

Transformations from

There are no known transformations

Corresponding ICD-9 Codes

200.7 Large cell lymphoma

Corresponding ICD-10 Codes

C83.3 Diffuse non-Hodgkins lymphoma, large cell (diffuse)

Corresponding ICD-10-CM Codes (U.S. only)

C85.2 Mediastinal (thymic) large B-cell lymphoma (effective October 01, 2015)

Signs and Symptoms

Drenching night sweats
Fever (for no known reason)
Localized anterosuperior mediastinal mass
Pain in the chest, abdomen, or bones (for no known reason)
Painless swelling in the lymph nodes
Skin rash or itchy skin
Superior vena cava syndrome (due to mediastinal mass)
Weight loss (for no known reason)

Diagnostic Exams

CT (CAT) scan
Complete blood count (CBC)
Laparoscopy (rarely performed)
Laparotomy (rarely performed)
MRI (magnetic resonance imaging)
PET (positron emission tomography) scan

Progression and Transformation

None

Epidemiology and Mortality

Age: 35 years median age (occurs predominantly in young adults)
Sex: female predominance
Survival: beyond 2 years

Sources

Swerdlow SH, Campo E, Harris NL, Jaffe ES, Pileri SA, Stein H, Thiele J (Eds):
WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues (Revised 4th edition)
IARC: Lyon 2017
Section: Mature B-cell neoplasms
Pages: 314-316

International Classification of Diseases for Oncology, Third Edition, First Revision. Geneva: World Health Organization, 2013.
Section: ICD-O-3.1 (2011) Morphological Codes
Pages: http://codes.iarc.fr/codegroup/2

National Cancer Institute
Section: General Information About Adult Non-Hodgkin Lymphoma (NHL)
Pages: https://www.cancer.gov/types/lymphoma/hp/adult-nhl-treatment-pdq
Glossary