PAPULOSQUAMOUS DERMATOSES
Psoriasis Vulgaris with Subtypes
(Figures 3.5C and 3.6A–C) - Polygenic inflammatory disease with chronic, recurrent course; affects 2% of population
- Bimodal onset with third or sixth decade; earlier onset associated with more severe disease
- Pathogenetic factors
- Abnormal T cell activation
- New view as TH17 disease; T cell-mediated autoimmunity toward poorly defined antigens
- Cytokine profile:
- ↑ IL-2, IFNγ (TH1 cytokines)
- ↑ IL-1, IL-6, TNFα (innate cytokines)
- ↑ IL-12 (stimulates TH1 cells)
- ↑ IL-23 (stimulates TH17 cells)
- ↑ IL-22, IL-17, TNFα (TH17 cytokines)
- IL-22 correlates with disease severity
- T cell disease supported by response to T cell inhibitors like cyclosporine; worsening through IFNγ
| | | | | | IL-12 and IL-23 have common subunit p40: target of ustekinumab | | | | | |
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- Abnormal keratinocytes
- ↑ Mitotic activity and leukocyte recruitment; keratinocytes move to upper layer in 3–5 days (vs. normal 28 days)
- ↑ Human β-defensin-2 (hBD2), secretory leukocyte protease inhibitor (SLPI), and skin-derived anti-leukoproteinase (SKALP): antimicrobial peptides resulting in ↓ risk of secondary infection
- ↑ Involucrin in all layers (except basal)
- Shed without loss of nucleus (parakeratotic scales)
- Epidermal expression of STAT-3, which induces upregulation of TGFα and ICAM-1
- Secrete IL-1, TNFα, IL-6, IL-8 (chemoattractant)
- Genetics (polygenic and multifactorial)
- HLA associations:
- Cw6 (strongest) associated with early onset
- B13, DR7, B17, B57 associated with earlier onset
- B27 associated with psoriatic arthritis
- A2 and Cw2 (weaker association)
| | | | | | B13, B17, Cw6: guttate psoriasis | | | | | |
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- In moderate to severe psoriasis, ↑ risk of cardiovascular disease; other comorbidities may include hypertension, obesity, dysplipidemia, diabetes mellitus; common genetic factors (B27) may also cause ↑ incidence of inflammatory bowel disease
- Triggering factors
- Physical trauma (Köebner phenomenon)
- Infection (especially streptococcal pharyngitis)
- Stress
- Medications (most commonly associated listed below)
- Lithium
- β-blocker
- Antimalarial
- ACEI
- NSAID
| Figure 3.7
A: Guttate psoriasis
B: Psoriasis involving nail
C: Erythrodermic psoriasis
(Courtesy of Dr. Paul Getz) |
- G-CSF
- Interferon
- Chronic plaque psoriasis presents with erythematous, scaly sharplybordered macules, papules and plaques covered with silvery scale over extensor surfaces (knees, elbows), scalp, gluteal cleft, ± genitalia, ± intertriginous areas; chronic course with flares
- Guttate psoriasis (Figure 3.7A) presents with acute-onset rain drop-like scaly papules on the trunk and extremities often in young patients; frequently preceded by streptococcal infection and eruption usually resolves completely within few months (may turn into chronic plaque psoriasis in adults)
- Special locations:
- Palms and soles (palmoplantar psoriasis)
- Intertriginous areas (inverse psoriasis)
- Psoriatic nails (Figure 3.7B): may affect nail matrix, bed or plate; may be sole involvement or part of extensive disease
- Pitting (nail matrix → focal parakeratosis in nail plate)
- Leukonychia (nail matrix)
- Onychodystrophy (nail matrix ± bed → subungual hyperkeratosis)
- Oil spots (nail bed → yellow brown spots)
- Onycholysis (nail bed → separation of plate from bed)
- Splinter hemorrhages (↑ capillary fragility in nail bed)
- Erythroderma (Figure 3.7C)
- Generalized erythema and scaling (>90% skin surface affected), ± leukocytosis, ↑ ESR, lymphadenopathy; may develop suddenly from guttate or stable psoriasis but typically due to inappropriate treatment of disease
- Histology: confluent parakeratosis (focal parakeratosis in guttate), hyperkeratosis, collection of neutrophils in stratum corneum (Munro microabscesses) and spinous layer (spongiform pustules of Kogoj), hypogranulosis, acanthosis with clubbed rete ridges, suprapapillary thinning, dilated blood vessels in papillary dermis, perivascular lymphocytes
- Treatment:
- Topicals
- Vitamin D3 analogues (i.e. calcipotriol, calcipotriene)
- Corticosteroids
- Calcineurin inhibitors (pimecrolimus/tacrolimus for intertriginous areas)
- Tazarotene
- Coal tar
- Anthralin
- Fixed combination betamethasone diproprionate/calcipotriol
- Oral
- Acitretin
- Methotrexate
- Cyclosporine
- Other
- Biologic agents
- Phototherapy (PUVA, NBUVB)
- Excimer laser
| | | | | | Topical calcipotriene may be inactivated in acidic environment (i.e. salicylic acid) | | | | | |
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| | Figure 3.5
A: Lupus miliaris disseminatus
faciei
(Courtesy of Dr. Iris K.
Aronson)
B: Pyoderma faciale
(Courtesy of Dr. Paul Getz)
C: Plaque psoriasis |
| Figure 3.6
A: Plaque psoriasis
B: Plaque psoriasis
(Courtesy of Dr. Paul Getz)
C: Guttate psoriasis |
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