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HMS IDD > T cell diseases of the skin > Flashcards

T cell diseases of the skin Flashcards

1
Q

Skin homing T cell antigens

A
  • CCR4
  • CLA
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2
Q

Lung homing T cell antigens

A
  • VLA-1
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3
Q

Gut homing T cell antigens

A
  • α4β7 integrin
  • CCR9
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4
Q

TRM phenotype

A
  • Accumulate in barrier tissues following T cell activation in these tissues
  • Persist in these tissues and confer antigen-dependent protection
  • Sessile and non-recirculating
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5
Q

There are ___ memory T cells residing in every square cm of skin

A

There are 1 million memory T cells residing in every square cm of skin

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6
Q

The population of resident T cells within skin is ___% of the circulating human T cell population.

A

The population of resident T cells within skin is 200% of the circulating human T cell population.

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7
Q

Local skin infection leads to the seeding of ___ with TRMs specific for antigens of the infectious agent.

A

Local skin infection leads to the seeding of the local area to a high degree and the total skin surface to a lower degree with TRMs specific for antigens of the infectious agent.

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8
Q

TRM and skin-tropic TCM give rise to distinct ____

A

TRM and skin-tropic TCM give rise to distinct inflammatory lesions in the skin

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9
Q

Inflammatory skin diseases caused by TRM

A

Psoriasis and mycosis fungoides

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10
Q

Cutaneous T cell lymphomas

A
  • aka CTCLs
  • Heterogeneous collection of non-Hodgkin’s lymphomas derived from skin-trafficking T cells
  • Mycosis fungoides and Sezary syndrome are most common
  • MF has a good prognosis, Sezary syndrome patients often do not live past 3-4 years of diagnosis without hematopoietic stem cell transplant. This is because MF is skin-limited while Sezary syndrome has systemic symptoms in lymphatics and blood
  • MF is a malignancy of TRMs, SS is a malignancy of TCMs
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11
Q

Mycosis fungoides

A
  • Skin-limited CTCL, malignancy of intradermal TRMs
  • Survival decreases with progression of skin lesions from patches, to plaques, to tumors
  • Treatment is palliative, not curative
  • Most lesions have some pruritis, ranging from little to severe
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12
Q

Early mycosis fungoides is often mislabeled as ___.

A

Early mycosis fungoides is often mislabeled as atypical psoriasis or eczema.

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13
Q

How do you tell early MF apart from other skin diseases?

A
  • Lesions often irregular in shape
  • peculiar in color (reddish brown, violaceous, or orange)
  • asymmetric in distribution
  • May be slightly scaled in patch-phase
  • Sometimes manifests as poikiloderma
  • Lymphadenopathy found in advanced disease
  • Skin biopsy is crucial to diagnose
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14
Q
A

Mycosis fungoides

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15
Q
A

Mycosis fungoides

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16
Q

Histopathologic findings of mycosis fungoides

A
  • Pautrier’s microabscesses within the epidermis (microabscesses of lymphocytes, often atypical lymphocytes)
  • Lymphocytic inflammation in the dermis, often with atypical lymphocytes
  • Lymphocytes with convoluted, cerebriform nuclei
  • Oligoclonality of T cells
    *
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17
Q

The TRMs involved in mycosis fungoides are ___.

A

The TRMs involved in mycosis fungoides are usually CD4, but sometimes CD8.

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18
Q

Treatment of mycosis fungoides

A
  • Topical steroids (in early disease)
  • UV light (UVA or UVB) in combination with psoralens
  • Topical agents such as nitrogen mustard or topical retinoids
  • Electron beam therapy
  • Low dose irradiation
  • Chemotherapy for systemic disease
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19
Q

Sezary syndrome

A
  • aka leukemic CTCL
  • Triad of: complete erythema, generalized lymphadenopathy, and abnormal T cells in the skin
  • T cell oligoclonality, CD4/CD8 ratio >10, absolute Sezary cell count at least 1,000 per microliter
  • May cause marked exfoliation
  • Edema, lichenification, pruritis, diffuse scaling
  • Lymphadenopathy, alopecia, onychodystrophy and palmoplantar hyperkeratosis common findings
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20
Q

Sezary cell

A
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21
Q

Differential for Sezary syndrome

A
  • May be difficult to distinguish from non-malignant forms of erythroderma
  • Psoriatic erythroderma at top of list
  • Atopic dermatitis or other dermatitis (irritant, contact)
  • pityriasis rubra pilaris
  • drug eruption (TEN)
  • idiopathic erythroderma
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22
Q
A

Sezary syndrome

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23
Q

Histopathology of Sezary syndrome

A
  • Epidermotropism of MF often absent in Sezary syndrome
  • In up to 1/3 patients, histopathologic findings nonspecific
  • Involved lymph nodes characteristically show a dense, monotonous infiltrate of Sézary cells and disturbance of normal architecture
  • Neoplastic T cells have a mature CD3 + , CD4 + , CD8 – phenotype and characteristically lack CD7 and CD26 expression
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24
Q

Treatment of Sezary syndrome

A
  • Being a leukemia, systemic treatment is required by definition
  • alemtuzumab (anti-CD52) is a T cell depleting agent that is quite effective, full remission in 50% of patients, response rate 100%
  • Most other treatments <30% response rate
  • extracorporeal photopheresis
  • Systemic IFN-α or IFN-γ therapy
  • systemic retinoids, methotrexate, HDAC inhibitors and chemotherapy regimens
  • In all patients with Sézary syndrome, a definitive cure requires stem cell transplantation.
25
Q

Extracorporeal photophoresis

A
  • White blood cells are removed from the patient several hours after psoralen ingestion, are externally exposed to UVA, and reinfused into the circulation
  • Its mechanism of action remains unclear but it appears to involve the generation of tolerogenic dendritic cells and increasing numbers of regulatory T cells.
26
Q

Wood’s light

A

Special frequency of light which accentuates depigmented skin. Used to help visualize vitiligo and other depigmenting skin diseases.

27
Q

White spots should be examined for:

A
  • Partial versus complete pigment loss
  • Presence of absence of scale
28
Q

Differential for white spots on skin

A
  • Post-inflammatory hypopigmentation
  • Vitiligo
  • Tuberous sclerosis
  • Tinea versicolor
  • Pityriasis alba

Of these, only vitiligo results in complete loss of pigment from lesions, and only tinea versicolor and pityriasis alba are associated with scale.

29
Q

Vitiligo key clinical features

A
  • Wood’s light accentuates completely depigmented macules without scale
  • Commonly seen in periorificial and dorsal hands, elbows, and knees
  • Vitiligo is a common cause of depigmentation
30
Q

Vitiigo

A
  • Aquired autoimmunity against self melanocytes, resulting in depigmentation in non-scaling patches
  • 1% prevalence, incidence highest in 10-30 y.o. group
  • Otherwise asymptomatic, but often medical attention is sought to avoid cosmetic disfigurement
    *
31
Q

Macules of vitiligo are ___ in shape.

A

Macules of vitiligo are round or oblong in shape.

32
Q

Vitiligo may affect. . .

A
  • Any area of skin or mucous membrane
  • Most common over extensor bony surfaces and periorificial areas
  • Involvement of hairy areas may result in depigmentation of hair
33
Q
A

Vitiligo involving the hair follicles of the eyelash

34
Q

Classification of vitiligo

A
  • Localized vitiligo
    • Focal : one or more macules in one area, but not clearly in a segmental distribution
    • Unilateral/segmental : one or more macules involving a unilateral segment of the body, usually stop at midline
    • Mucosal : mucous membranes alone
  • Generalized vitiligo
    • Vulgaris : scattered patches that are widely distributed
    • Acrofacial : distal extremities and face
    • Mixed : various combinations of segmental, acrofacial and/or vulgaris
  • Universal vitiligo
    • Complete or nearly complete depigmentation
35
Q

Vitiligo chart

A
36
Q

__% of vitiligo patients have generalized vitiligo

A

90% of vitiligo patients have generalized vitiligo

37
Q

Autoimmune diseases associated with vitiligo

A
  • Grave’s disease
  • Pernicious anemia
  • Addison’s disease
38
Q

Histopathology of vitiligo

A
  • Loss of melanocytes in affected areas (may require special stains to appreciate)
39
Q

Pathology of vitiligo

A

Three potential etiologies

  1. Autoimmune (driven by CD8 T cells and IFNg. Anti-IFNg therapies reverse pathology in these cases)
  2. Neural (Neurochemical mediators driving melanocyte apoptosis. Known to be the true etiology for many cases of disease)
  3. Self-destruction (due to intrinsic defects in the melanocytes or due to defective defense against oxidative stress leading to destruction of melanocyte)
40
Q

Treating vitiligo

A
  • No cure, but there are treatments to slow down or halt progress
  • Topical, high-potency steroids effective in some patients
  • Topical macrolides also effective without steroid downsides
  • UVB therapy recommended for widespread vitiligo (308 nm narrow-band UVB therapy ideal)
  • Skin grafting from unaffected area
  • Melanocyte isolation, culture, and re-introduction is in trial right now
  • Covermark and Dermablend are cosmetics which are designed to cover vitiligo patches and blend in with unaffected skin
  • In selected individuals, depigmentation of remaining pigmented skin may be the therapy of choice. This is done with 20% benoquin. It is irreversible, so the patient must be SURE
  • Type II IFN and JAK inhibitor studies currently underway, early results positive
41
Q

The course of vitiligo is ___.

A

The course of vitiligo is unpredictable.

42
Q

___ may occur in cases of chronic vitiligo.

A

Spontaneous repigmentation may occur in cases of chronic vitiligo.

Although, it is often incomplete

43
Q

Most concerning aspect of vitiligo

A
  • Social stigma and body image
  • particularly deeply pigmented patients may suffer social stigmatization
  • In some cultures, vitiligo has been confused with the white spots of leprosy and has resulted in social ostracism
44
Q

Key features of alopecia areata

A
  • Form of autoimmunity
  • Acute onset of well-circumscribed, oval patches of non-scarring alopecia
  • No gender preference, onset typically early adulthood
45
Q
A

Alopecia areata

46
Q

Alopecia areata association with other autoimmune diseases

A
  • 25% of patients have another form of autoimmunity
  • Type 1 diabetes common comorbidity
  • Grave’s disease
  • vitiligo
47
Q

Concordance rate for alopecia areata

A

55%

Suggests powerful genetic influence, but also important environmental/developmental factors

48
Q

Non-autoimmune associations with alopecia areata

A
  • Atopic dermatitis the single most common comorbidity
    *
49
Q

Anatomy of pilosebaceous unit

A
50
Q

Physical examination of alopecia areata

A
  • Well-circumscribed, round or ovoid patches
  • Sometimes erythema and slight tenderness
  • Subsequent slight depression of scalp and studding with exclamation point hairs
  • Eyebrows, eyelashes, beard, and other body hair may also be affected
  • Fine stripping or pitting of nails also associated
51
Q

alopecia totalis

A

loss of all scalp hair

52
Q

alopecia universalis

A

Loss of all body hair

53
Q

Differential for alopecia

A
  • Alopecia areata
  • Secondary syphilis
  • Trichotillomania (Ill-marginated,
    irregular patches of alopecia containing the stubble of broken hairs are typical)
  • Fungal infection (usually assc. with redness and scale)
54
Q

Histopathology of alopecia areata

A
  • presence of small, dystrophic hair structures
  • lymphocytic infiltrate surrounds the early anagen hair bulbs
55
Q

Normal anagen hair follicle keratinocytes typically lack expression of . . .

A

. . . both Class I and Class II MHC! Suggests immunologic privilege of the human hair follicle bulb

56
Q

Treatment of alopecia

A
  • There is no cure
  • For local lesions, topical potent steroids or intralesional injection of triamcinolone sometimes effective
  • immunotherapy by induction of allergic contact dermatitis
  • Phototherapy
  • topical minoxidil
  • oral cyclosporine
  • Novel strategies are inhibition of JAKs and induction of CTLA-4
57
Q

Course of alopecia areata

A
  • Large areas/long duration (>1 year) associated with poor prognosis
  • Overall though, variable and unpredictable
  • Most patients with localized disease have spontaneous recovery. However, relapses are not uncommon
58
Q

TRM vs TCM on flow

A
59
Q
A

Tinea versicolor

Fungal infection. A common cause of pigment loss

HMS IDD (28 decks)

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