B Cell Lymphoma Flashcards
(60 cards)
A 65-year-old man presents with a solitary, violaceous nodule on his upper back. Histology shows nodular and diffuse dermal infiltrates of centrocyte-like cells. Immunostaining is CD20+, Bcl-6+, CD10+/–, and Bcl-2 negative.
What is the most likely diagnosis?
A. Systemic follicular lymphoma with skin involvement
B. Primary cutaneous marginal zone lymphoma
C. Primary cutaneous follicle center lymphoma
D. Diffuse large B cell lymphoma, leg type
C. Primary cutaneous follicle center lymphoma
PCFCL typically presents on the head, neck, or trunk in older males.
Histology: Centrocyte-dominated infiltrate, may have centroblasts.
Immunophenotype:
- CD20+, Bcl-6+
- CD10: variable
- Bcl-2 negative (critical point distinguishing it from systemic follicular lymphoma)
Systemic FL would be Bcl-2 positive and often involve deeper nodes or marrow.
Which subtype of pCBCL has been reclassified in the ICC 2022 as a lymphoproliferative disorder rather than a true lymphoma?
Primary cutaneous marginal zone B-cell lymphoproliferative disorder (PCMZLD) was downgraded in classification from lymphoma to lymphoproliferative disorder due to its extremely indolent nature and lack of systemic spread.
Which of the following immunostains is most useful in distinguishing DLBCL, leg type from PCFCL, diffuse type?
A. CD10
B. MUM-1
C. CD5
D. CD23
B. MUM-1
MUM-1 (IRF4) is a marker of late B-cell differentiation (post-germinal center / activated B cells).
DLBCL, leg type is MUM-1+, Bcl-2+, FOXP1+
In contrast, PCFCL is typically MUM-1 negative and may be CD10+/–, Bcl-6+.
**MUM = Mature + Malignant → MUM-1+ suggests aggressive behavior like DL
A cutaneous B cell lymphoma with strong Bcl-2 expression and a t(14;18) translocation on FISH is most consistent with:
A. PCFCL
B. Systemic follicular lymphoma involving the skin
C. PCMZLD
D. EBV+ mucocutaneous ulcer
B. Systemic follicular lymphoma involving the skin
t(14;18) involves BCL2 and IGH, seen in systemic follicular lymphoma.
Primary cutaneous FL (PCFCL) is typically Bcl-2 negative and lacks t(14;18).
So if you see this translocation in a skin lesion → it’s systemic FL with secondary skin involvement
What is the typical MUM-1 and Bcl-2 staining pattern in DLBCL, leg type?
A. MUM-1– / Bcl-2–
B. MUM-1+ / Bcl-2+
C. MUM-1– / Bcl-2+
D. MUM-1+ / Bcl-2–
B. MUM-1+ / Bcl-2+
DLBCL, leg type is an activated B-cell type:
MUM-1+
Bcl-2+
Also FOXP1+
These markers help distinguish it from PCFCL, which is generally MUM-1– and Bcl-2–.
Which type of pCBCL is most associated with Borrelia burgdorferi DNA in lesions, especially in endemic regions of Europe?
A. PCFCL
B. DLBCL, leg type
C. PCMZLD
D. EBV+ mucocutaneous ulcer
C. PCMZLD
Primary cutaneous marginal zone B-cell lymphoproliferative disorder has been associated with Borrelia burgdorferi, especially in Europe (Austria, Germany, Switzerland).
Similar to Helicobacter pylori in gastric MALT lymphoma, suggesting chronic infection → antigen-driven lymphoproliferation.
Which statement about PCMZLD is TRUE?
A. Commonly ulcerates and causes B symptoms
B. Frequently progresses to nodal disease
C. Usually presents on the lower legs with aggressive progression
D. Often shows plasmacytic differentiation and responds to local therapies
D. Often shows plasmacytic differentiation and responds to local therapies
PCMZLD:
Indolent
No systemic symptoms
Plasmacytoid cells often present
Responds to surgical excision, topical steroids, IL steroids, or radiotherapy
In DLBCL, leg type, which of the following factors is associated with a worse prognosis?
A. Low LDH
B. CD10 expression
C. Multiple skin lesions outside the legs
D. Elderly male sex
D. Elderly male sex
rognostic factors:
Older age
Multiple lesions
Localization outside the legs is actually favorable (unexpectedly!)
CD10 expression is rare and not prognostic
A 78-year-old woman presents with multiple red nodules confined to the lower legs. Histology shows large centroblasts with strong MUM-1 and FOX-P1 positivity.
What is the most appropriate first-line treatment?
A. Intralesional triamcinolone
B. Oral doxycycline
C. R-CHOP chemotherapy
D. Surgical excision only
C. R-CHOP
This is classic DLBCL, leg type
Requires systemic chemotherapy — R-CHOP is first-line
Others (like triamcinolone, doxycycline, excision) are inappropriate due to high-grade behavior
Which subtype of pCBCL may present as a mucocutaneous ulcer in immunosenescent or immunocompromised patients and is associated with EBV?
A. DLBCL, leg type
B. Intravascular DLBCL
C. EBV+ mucocutaneous ulcer
D. Plasmablastic lymphoma
C. EBV+ mucocutaneous ulcer
Seen in:
Elderly or immunosuppressed patients (iatrogenic or age-related)
Often solitary, well-circumscribed ulcer
Histology: Reed-Sternberg–like cells, strong EBV positivity
Indolent, often resolves with immune reconstitution or reduction of immunosuppression
Histology of PC - marignal cell lymphoproliferative disorder?
Small- to medium-sized lymphocytes with monocytoid or plasmacytoid features
Nodular or patchy pattern
Often has germinal center remnants or plasma cells with light chain restriction
Indolent, often in young adults
Common on arms and trunk, not legs
Histology of Primary Cutaneous Follicle Center Lymphoma (PCFCL)
Dense dermal lymphocytic infiltrate, sparing the epidermis (grenz zone)
Mixture of centrocytes and centroblasts, sometimes in follicular or diffuse patterns
No significant cytologic atypia compared to DLBCL
Common on scalp, forehead, upper trunk
Bcl-2–negative, Bcl-6+/CD10+/–
HIstology - Primary Cutaneous Diffuse Large B-Cell Lymphoma, Leg Type (PCDLBCL-LT)
Sheets of large atypical lymphoid cells with prominent nucleoli
High mitotic activity
Retains a grenz zone (a helpful clue), but the cells are cytologically aggressive
Immunostaining: Bcl-2+, MUM-1+, FOXP1+
Almost always found on the legs of elderly women, but can occur elsewhere
Primary cutaneous B-cell lymphomas are defined by the presence of B-cell lymphoma confined to the skin for ≥6 months after diagnosis.
True
Primary cutaneous marginal zone B-cell lymphoma (PCMZL) is now considered a lymphoproliferative disorder rather than a true lymphoma under the 2022 ICC classification.
True
Primary cutaneous follicle center lymphoma (PCFCL) and nodal follicular lymphoma are biologically and genetically identical and should be treated similarly
False
PCFCL is Bcl-2 negative in most cases and lacks the t(14;18) IGH-BCL2 translocation typical of nodal FL.
They also have distinct gene expression profiles and clinical behavior.
Systemic FL requires systemic therapy; PCFCL can often be managed locally or conservatively.
Diffuse large B-cell lymphoma, leg type (DLBCL-LT) is considered a high-grade B-cell lymphoma with a poorer prognosis than other cutaneous B-cell lymphomas.
True
PCFCL is characterized histologically by a dense dermal infiltrate of centrocyte-like cells, usually with sparing of the epidermis (grenz zone).
True
DLBCL-LT typically expresses CD20, Bcl-2, FOXP1, and MUM-1, and is CD10 negative.
True
PCMZL lesions may show plasma cell differentiation, with light-chain restriction and Bcl-2 positivity.
True
Primary Cutaneous Marginal Zone Lymphoproliferative Disorder (PCMZLD) can show:
Plasmacytoid differentiation
Monotypic light chain restriction (kappa or lambda)
Bcl-2 positivity
PCFCL is typically Bcl-2 positive, and this is an important distinguishing feature from systemic follicular lymphoma.
False
PCFCL is typically Bcl-2 NEGATIVE
PCMZL has been associated with Borrelia burgdorferi infection in some European endemic regions.
True
EBV-positive mucocutaneous ulcer is a subtype of pCBCL that shows spontaneous regression and is commonly seen in immunosenescent or immunosuppressed patients.
True
EBV+ mucocutaneous ulcer is:
Self-limited
Often seen in elderly (immunosenescence) or iatrogenic immunosuppression
Histology shows Reed–Sternberg–like B-cells, EBV+, CD30+, CD20+, EBER+
Usually regresses with reduction of immunosuppression
FISH analysis for t(14;18) is useful to distinguish between PCFCL and secondary systemic follicular lymphoma.
True
