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Hematopathology WHO T cell Neoplasms > Primary Cutaneous Peripheral T cell Lymphomas > Flashcards

Primary Cutaneous Peripheral T cell Lymphomas Flashcards

1
Q

What disease entities are contained

in this category because they are rare ?

A
  • Primary cutaneous gamma/delta T cell lymphoma
  • Primary cutaneous CD8+ aggressive epidermotropic cytotoxic T cell lymphoma
  • Primary cutaneous acral CD8+ T cell lymphoma
  • Primary cutaneous CD4+ small/medium T cell LPD
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2
Q

What is the definition of

PC G/D T cell lymphoma?

A
  • primary to the skin
  • mature, activated g/d T cells
  • cytotoxic phenotype

IMP: G/D TCR may be seen in MF or Lymphomatoid papulosis so just because the G/D TCR is rearranged doesn’t mean it’s this entity.

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3
Q

What is the epidemiology of

PC G/D T cell lymphoma ?

A
  • very rare, 1% of cuteneous T cell lymphomas
  • most occur in adults
  • no sex predilection
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4
Q

What is the etiology of

PC G/D T cell lymphoma ?

A
  • distribution of the disease reflects normal G/D T cells which are essential in the innate immun response
  • it is felt that this disease may arise from chronic antigenic stimulation
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5
Q

What is the localization of PC

G/D T cell lymphoma ?

A
  • generalized skin lesions with variable clinical morphology (see pictures p. 397)
  • primarily affect the extremities
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6
Q

What are the clinical features

of PC G/D T cell lymphoma?

A
  • clinical presentation is variable with plaque like lesions (epidermotropic lesions) to deep dermal/subQ tumors
  • usually on extremities but can be at other sites
  • dissemination to mucosal or other areas is frequent with progression
  • NO involvement of LN, spleen or bone marrow is usually identifed
  • HLH often develops
    • particularly with panniculitis like tumors
  • B symptoms seen in most adults
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7
Q

What are the microscopic findings

of PC G/D T cell lymphoma ?

A
  • 3 major patterns:
    • epidermotropic
    • dermal
    • subcutaneous
  • Epidermal infiltrate can be mild to marked
  • SubQ shows rimming of fat cells
    • similar to subcutaneous panniculitis like T cell lymphoma
    • BUT this entity also has dermal/and or epidermal involvement
  • medium to large in size
  • large blastic or anaplastic cells are infrequent
  • angioinvasion with apoptosis and necrosis is common
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8
Q

What is the immunophenotype of

PC G/D T cell lymphoma?

A
  • delta TCR gene positive
  • CD3 and CD2+
  • CD7 +/- and CD56+
  • CD5 -
  • strong expression of cytotoxic proteins:
    • TIA1, Granzyme B and Perforin
  • CD4 and CD8 are both usually negative
    • CD8 may be expressed in some cases
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9
Q

What is the postulated normal counterpart

of PC G/D T cell lymphoma ?

A
  • functionally mature and activated cytotoxic G/D T cells
    • of the innate immune system
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10
Q

What is the genetic profile

of PC G/D T cell lymphoma ?

A
  • TRG and TRD genes are clonally rearranged
    • V delta 2, consistent with prevalence of these residing in the skin
  • EBV is negative
  • STAT5B and rarely STAT3 can have activating mutations
    • which makes sense because many cytotoxic T cell malignancies have activation of the JAK/STAT pathway
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11
Q

What are the prognostic and predictive

factors for PC G/D T cell lymphoma?

A
  • usually resistent to multiagent chemotherapy and radiation
  • median survival is 15 months
    • poor prognosis
    • subcutaneous lesions are particularly bad
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12
Q

What is the definition of PC CD8+

aggressive epidermotropic cytotoxic T cell lymphoma ?

A
  • provisional entity
  • proliferation of CD8+ cytotoxic T cells with marked epidermotropism and epidermal necrosis
  • what differentiates this entity from other CD8+ cutaneous T cell lymphomas is:
    • clinical presentation
    • clinical behavior
    • histologic features
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13
Q

What is the epidemiology of PC

CD8+ aggressive epidermotropic

cytotoxic T cell lymphoma?

A
  • very rare disease ( < 1% of all cutaneous lymphomas)
  • occurs mainly in adults
  • no known predisposing factors
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14
Q

What is the localization of PC CD8+

aggressive epidermotropic cytotoxic T cell lymphoma ?

A
  • most patients present with generalized skin lesions
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15
Q

What is the clinical presentation of PC CD8+

aggressive epidermotropic cytotoxic T cell

lymphoma?

A
  • disseminated, eruptive papules, nodules and/or tumors with central ulceration and necrosis
    • rarely it presents as a localized lesion
  • IMP:
    • these lymphomas can disseminate to other visceral sites:
      • lungs, testes, CNS, oral mucosa
    • LN are often spared
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16
Q

What are the microscopic features of PC, CD8+

aggressive epidermotropic cytotoxic

T cell lymphoma ?

A
  • variable morphology
  • can have a lichenoid pattern with marked pagetoid epidermotropism and subepidermal edema
    • or deeper dermal infiltrates with barely any epidermotropism (more likely seen in the localized variant)
  • epidermis shows necrosis, ulceration and blister formation
  • destruction of adnexal structures is common
  • tumor cells
    • small-medium-large
    • blastic or pleomorphic nuclei are common
17
Q

What is the immunophenotype of PC

CD8+ aggressive, cytotoxic, epidermotropic

T cell lymphoma ?

A
  • CD3+, CD8+, CD4-
  • alpha Beta F1 +
  • Granzyme B+, Perforin +, TIA1+
  • CD45RA+, CD45RO-
  • CD2 and CD5-
  • CD7 variable expression
  • CD30 - in most cases

IMP: difficult clinically and by immunophenotype to differentiate from lymphomatoid papulosis (type D)

18
Q

What is the normal counterpart of

PC CD8+ aggressive epidermotropic

cytotoxic T cell lymphoma ?

A
  • a skin-homing, CD8+ cytotoxic T cell
  • alpha beta type
19
Q

What is the genetic profile of PC CD8+

aggressive epidermotropic cytotoxic

T cell lymphoma ?

A
  • specific genetic abnormalities have not been identified
  • No EBV ISH
20
Q

What is the prognosis and predictive factors

for PC CD8+ aggressive epidermotropic

cytotoxic T cell lymphoma ?

A
  • aggressive disease with median survival of 12 months
  • no difference in clinical outcome between large and small cell morphology and generalized or localized variant
21
Q

What is the definition of PC acral CD8+

T cell lymphoma ?

A
  • Rare, cutaneous tumor composed of a skin infiltration of atypical medium-sized cytotoxic lymphocytes
  • preferential involvement of acral sites, particularly the ears
  • associated with a good prognosis
22
Q

What is the epidemiology of

PC CD8+ acral T cell lymphoma ?

A
  • disease of adults
  • median age is 53 years
  • male predominance is seen
23
Q

What is the etiology of PC

CD8+ acral T cell lymphoma ?

A
  • unknown etiology
  • an infectious agent is suspected but has not been proven
24
Q

What are the clinical features of

PC CD8+ acral T cell lymphoma?

A
  • generally a localized lesion
    • reddish papule or nodule
    • slow growing over weeks to months
  • most frequent sites: ear > nose > foot
  • rarely can have multiple lesions or bilateral lesions of the same site
25
Q

What are the microscopic features of

PC CD8+ acral T cell lymphoma ?

A
  • monotonous dermal infiltration of medium sized lymphocytes
  • they have irregular, frequently folded nuclei and small nucleoli
  • mitoses and apoptoses are rare
  • reactive B lymphoid aggregates of follicles may be interspersed with this infiltrate
    • other inflammatory cells should be rare or absent (eos, histiocytes, etc)
  • epidermis is spared with a grenz zone
  • underlying adipose tissue is almost always involved
  • skin appendages are always spared
  • angiodestruction and necrosis are never seen
26
Q

What is the immunophenotype of PC

CD8+ acral T cell lymphoma ?

A
  • CD3, CD8, TIA-1 and beta F1 are positive
    • TIA-1 shows golgi like staining pattern
  • CD2, CD5 and CD7 are regularly positive but may be weak or lost
  • CD4 always negative
  • Granzyme and Perforin are usually negative
  • CD56, CD57, CD30, TdT, EBV and TFH cell markers are negative
  • CD68
    • frequently patchy positive with golgi like pattern of staining
  • Ki67
    • usually <10%
    • if >50% consider a different lymphoma
27
Q

What is the postulated normal counterpart of

PC CD8+ acral T cell lymphoma ?

A
  • CD8+ skin homing T cell
    • but other locations of have been described including the GI tract
    • thought to now be a CD8+ memory T cell
28
Q

What is the genetic profile of PC

CD8+ acral T cell lymphoma ?

A
  • specific genetic alterations have not yet been described
  • EBV is negative
29
Q

What are the prognostic and predictive factors

of PC CD8+ acral T cell lymphoma ?

A
  • this lymphoma has a very good prognosis
  • complete remission after surgical excision or local radiation
  • no evidence of dissemination
  • local recurrence may happen
  • NO chemotherapy is needed
30
Q

What is the definition of PC

CD4+ LPD ?

A
  • small/medium size cells with pleomorphic morphology
  • present with a solitary skin lesion without evidence of plaques or patches of MF
    • similar clinical presenation to cutaneous pseudo- T cell lymphoma with a nodular growth pattern
31
Q

What are the epidemiology and localization for

PC CD4+ T cell LPD ?

A
  • rare disease, ~2% of all skin T cell lymphomas
  • usually present as a solitary plaque or nodule
    • common on the face, neck or upper trunk
32
Q

What are the clinical features of PC

CD4+ T cell LPD ?

A
  • patients are usually asymptomatic
  • single slow-growing lesion
    • rare cases have multiple lesions
  • No clinical evidence of MF should be seen
33
Q

What are the microscopic findings for PC

CD4+ T cell LPD ?

A
  • dense or diffuse or nodular infiltrates within the dermis and a tendency to infiltrate the subcutis
  • epidermotropism can be focally present
    • IF conspicuous the diagnosis of MF should be considered
  • cytology
    • predominance of small/medium pleomorphic T cells
    • <30% can be large and pleomorphic
    • CD4+ T cells are usually admixed with small, reactive CD8+ T cells, B cells, PC, and histiocytes, including multinucleated giant cells
34
Q

What is the immunophenotype of PC CD4+

T cell LPD ?

A
  • CD3+, CD4+, CD8-, CD30-
  • Loss of pan T cell antigens (except for CD7) is uncommon and cytotoxic proteins are not expressed
  • atypical T cells express:
    • PD1, BCL6 (variable), and CXCL13 suggesting TFH derivation
    • CD10 is negative
  • Ki67 is usually low 5-20% at most
35
Q

What is the postulated normal counterpart

for PC CD4+ T cell LPD ?

A
  • skin-homing CD4+ T cell with TFH-cell characteristics
36
Q

What is the genetic profile of PC

CD4+ T cell LPD ?

A
  • TCR genes are usually clonally rearranged
  • specific genetic abnormalities have not been identified
  • EBV is negative
37
Q

What are the prognostic and predictive factors

for PC CD4+ T cell LPD ?

A
  • excellent prognosis
  • intralesional steroids, surgical excision or radiotherapy are preferred treatments
  • local recurrences are rare

Hematopathology WHO T cell Neoplasms (14 decks)

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