Difference between revisions of "Non-malignant skin disease"

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==Dermatomyositis==
==Dermatomyositis==
:''For the muscle manifestations see: [[Neuromuscular_pathology#Dermatomyositis]]''.
:''For the muscle manifestations see: [[Neuromuscular_pathology#Dermatomyositis]]''.
===General===
*Complement mediated disease - membrane attack complex.
*Usually middle age.
*Associated skin rash is common.
**May precede or follow muscle pathology.
*Associated with malignancy in approximately 10% of cases.<ref name=pmid20398365>{{cite journal |author=Chen YJ, Wu CY, Huang YL, Wang CB, Shen JL, Chang YT |title=Cancer risks of dermatomyositis and polymyositis: a nationwide cohort study in Taiwan |journal=Arthritis Res. Ther. |volume=12 |issue=2 |pages=R70 |year=2010 |pmid=20398365 |pmc=2888225 |doi=10.1186/ar2987 |url=}}</ref>
===Gross===
===Gross===
*Have lesions on the knuckle - Gottron's papulle
*Have lesions on the knuckles - ''Gottron's papules''.


===Microsopic===
===Microsopic===

Revision as of 04:42, 12 September 2011

Non-malignant skin disease is relatively common. The pathology may or may not be specific. Some diseases require clinical information to diagnose.

An introduction to dermatopathology is in the dermatopathology article. Nevi (moles) and other melanocytic lesions are dealt with in the article melanocytic lesions.


Inflammatory conditions

Classification

  • Bullous.
  • Interface.
  • Nodular & diffuse.
  • Spongiotic.
  • Vasculitis.
  • Perivascular.
  • Panniculitis.
  • Psoriasiform.

Tabular comparison of inflammatory skin disease (adapted from Brinster[1]):

Pattern Key histologic feature Subclassifications Example
Bullous "Empty space" -Subcorneal
-Suprabasillar
-Subepidermal
-Pemphigus foliaceus
-Pemphigus vulgaris
-Dermatitis herpetiformis
Interface Inflammation at DE junction -Vacuolar (minimal)
-Lichenoid (band-like)
-Erythema multiforme, SLE
-Lichen planus
Nodular & diffuse Nodular & diffuse ?
Spongiotic Edema between keratinocytes -Acute
-Subacute
-Chronic
-Poison Ivy
-Nummular dermatitis
-Atopic dermatitis
Vasculitis Inflammation of vessel wall ? ?
Perivascular Inflammation around vessels ? ?
Panniculitis Inflamm. of adipose tissue -Septal
-Nodular
-Erythema nodosum
-Erythema induratum
Psoriasiform Epidermal thickening
and long rete ridges
-Regular
-Irregular
-Psoriasis
-Lichen simplex chronicus

Notes:

  • DE junction = dermal-epidermal junction.
  • The "empty space" in bullous disease in situ is filled with fluid.

Psoriasis

General

  • Can be subclassified.

DDx:

  • Psoriasis vulgaris (most common).
  • Psoriatic arthritis.
  • Drug-induced.
  • Others.

Microscopic

Features:[2][1]

  • Regular epidermal thickening - as very long rete ridges (described as "test tube-morphology") - key feature.
    • Epidermis between rete ridges thin ("thinning of suprapapillary plate").
  • Parakeratosis.
  • Thin/absent granular layer.
  • Dilated blood vessels in superficial dermis.
  • Neutrophil clusters (Munro microabscess).

Seborrheic dermatitis

General

  • Very common.

Microscopic

Features:[3]

  • Spongiosis (epidermal edema).
  • Acanthosis (epidermal thickening).
  • "Follicular lipping" = parakeratosis with neutrophils.
  • Perivascular neutrophils and lymphocytes.

Systemic lupus erythematosus

General

  • Systemic disease with multi-organ manifestations.

Microscopic

Features:

  • Lymphocytic interface dermatitis.[4]
  • Basal layer vacuolation.[5]
  • Intradermal mucin.

Dermatomyositis

For the muscle manifestations see: Neuromuscular_pathology#Dermatomyositis.

General

  • Complement mediated disease - membrane attack complex.
  • Usually middle age.
  • Associated skin rash is common.
    • May precede or follow muscle pathology.
  • Associated with malignancy in approximately 10% of cases.[6]

Gross

  • Have lesions on the knuckles - Gottron's papules.

Microsopic

Features:

  • Lymphocytic interface dermatitis (inflammation at the dermal-epidermal junction).
  • Loss of rete ridges.

Lichen planus

General

  • An oral pathology.
  • May be seen where the sun don't shine - penis,[7] vulva and vagina.[8]

Etiology:

  • Autoimmune disease, T-cell–mediated.[9]

Clinical:[10]

  • 6 Ps: pruritic (itchy), purple, polygonal, planar papules and plaques.

Gross

  • Wickham striae = white lines/dots.
    • Due to hypergranulosis.

Microscopic

Features:[11][12]

  • Loss of basal cells (stratum basale) -- key feature.
  • Loss of rete ridges/formation of pointed rete ridges "sawtoothing".
  • Interface dermatitis (lymphocytes at dermal-epidermal junction).
  • Hypergranulosis; stratum granulosum thickened (grossly seen as "Wickham stria" = white lines).
  • Hyperkeratosis; stratum corneum thickened.
  • Necrotic basal cell in dermis = colloid bodies = Civatte bodies.[13]

DDx:

  • Bullous disease, subepithelial vesicular.
  • Lichenoid keratosis - parakeratosis prominent.

Notes:

  • Hyperkeratosis and hypergranulosis are not seen in erythema multiforme.
  • Colloid bodies = cytoid bodies = Civatte bodies = hyaline bodies = apoptotic bodies.[14]

Images:

Lichen sclerosus

Microscopic

Features:[15]

  • Subepithelial fibrosis - key feature.

Psoriasis

General

Clinical:

  • Auspitz sign = pin-point bleeding on removal of scale.
  • Koebner phenomenon = lesions form at site of trauma.

Microscopic

Features:[16]

  • Acanthosis + long rete ridges - key feature.
  • Parakeratosis.
  • Dilated vessels in superficial dermis (give rise to Auspitz sign).
  • Spongiform pustules = PMNs in stratum spinosum.
  • PMNs in parakeratotic stratum corneum (Munro microabscess).

Other

Squamous cell hyperplasia

General

  • Variant of spongiotic dermatitis.[19]

Etiology:[20]

  • Pruritus (itchness) -> mechanical trauma -> lichenification (thickened/leathery[21].

Microscopic

Features:[15]

  • Acanthosis (epithelial thickening).
  • Hyperkeratosis.

Other features:[22]

  • Spongiosis (epidermal intercellular edema -- cells appear to have a clear halo around 'em).
  • Parakeratosis = retention of nuclei in the stratum corneum.

Images:

Very common

Dermatophytosis

General

Microscopic

Features:

  • Microorganisms - key feature.
    • Often hyphae (candida) - like twigs of a tree... branching.
  • Perivascular inflammation.
  • Exocytosis - blood cell infiltrate the epidermis.

Stains

Cicatrix

General

  • Previous surgery, biopsy, trauma.

Microscopic

Features:

  • Loss of adnexal structures.
  • Dense collagen - fibers run parallel to the dermal-epidermal (DE) junction.
  • Loss of dermal papilla.

Image:

Fibroepithelial polyp

  • AKA acrochordon, skin tag.

General

  • Benign.
  • Older people.
  • May be associated with pregnancy, diabetes, intestinal polyposis.[23]

Gross

  • Raised skin-coloured lesion.

Image:

Microscopic

Features:

  • On a stalk / epithelium on three sides.
  • Benign epidermis.

Image:

Actinic keratosis

  • AKA solar keratosis. (???)

General

Clinical: yellow-brown scaly, patches, sandpaper sensation.

Risk factors:[25]

  • Sun exposure.
  • Immune suppression (e.g. organ transplant recipients).

Microscopic

Features:[26]

  • Epidermal nuclear atypia:
    • Variation is size, shape and staining.
      • Nuclear enlargement - key feature.
        • Should involve the basal layer.
  • Abnormal epidermal architecture:
    • Pallisading. (???)
  • +/-Parakeratosis.
  • +/-Irregular acanthosis.

Image:

Seborrheic keratosis

  • Abbreviated SK.

General

  • Benign.
  • Most common tumour in older people.[27]
  • "Large number" of SKs = paraneoplastic syndrome (Leser–Trélat sign).[28]

Epidemiology:

  • Old people.
  • Usu. in sun exposed area.[29]

Gross

  • "Stuck-on" appearance - raised lesion.

Image(s):

Microscopic

Features:[28]

  • Raised above skin surface.
  • Border sharply demarcated.
  • Hyperkeratosis - stratum corneum extra thick.
  • Horn cysts - intraepidermal collections of keratin.
  • Clusters of cells with brown granular material in the superficial dermis/dermoepidermal junction - pigmented melanocytes.

Images:

Verruca vulgaris

General

  • AKA common wart.
  • Etiology - HPV.

Notes:

Microscopic

Features:[30]

  • Hyperkeratosis (more keratin - thick stratum corneum).
  • Hypergranulosis (thicker stratum granulosum).
  • Acanthosis (thickening of the stratum spinosum).
  • Rete ridges lengthened (~7-10x normal).
  • Large blood vessels at the dermal-epidermal junction.

Memory device: there is more of everything - more s. corneum, s. granulosum, s. spinosum, longer rete ridges, more (larger) blood vessels.

Images:

Pilomatricoma

  • AKA calcifying epithelioma of Malherbe[31], AKA pilomatrixoma.

General

  • Benign skin tumour.
  • Most common solid skin tumour of children.[32]
  • CTNNB1 gene mutation important in pathogenesis.[33]

Clinical:

  • Hard nodule - calcification.
  • +/-Painful.

Treatment:

  • Surgical excision.[32]

Microscopic

Features:[34]

  • Lower dermis/subcutaneous adipose lesion; thus, usu. surrounded by connective tissue.
    • Sharpy demarcated island of cells.
    • Calcification in 75% - with calcium staining (von Kossa).
  • Cells:[35]
    • Basaloid epithelial cells - have prominent nucleoli.
    • Anucleate squamous cells ("ghost cells").
    • Giant cell foreign body type granulomas (form in reaction to keratin).

Notes:

  • Keratin a prominent feature on cytology - lots of orange stuff.

Images:

DDx:

Dermatofibroma

  • Abbreviated DF.

General

  • AKA fibrous histiocytoma.
  • Reactive process -- it is not a neoplasm.
  • Usually associated with previous trauma.
    • In women... usually legs.

Microscopic

Features:[36]

  • Prominent fibrous bundles, especially at the edge of the lesion.
    • Surrounded by spindle cells (fibroblasts).
      • Usually thought of as fibroblasts surrounded by fibrous material ("collagen-trapping").
  • Lack of adnexal structures, i.e. no sweat glands, no hair.
  • +/-Epidermal changes - known as "dirty fingers":[37]
    • Acanthosis (thickened epithelial layer - specifically thickened stratum spinosum).
    • Basal keratinocyte hyperpigmentation.

Images:

DDx:

Subtypes

Like all common things... there are subtypes:[38]

  • Cellular.
  • Deep penetrating.
  • Lipidized - with foamy macrophages, hemorrhage and Touton-like giant cells.
  • Epithelioid cell histiocytoma.
  • Fibrotic.
  • Aneurysmal - large blood filled + features of lipidized.
  • Granular cell dermatofibroma.
  • Dermatofibroma with monster cells.

IHC

Features:[39][40]

  • Factor XIIIa +ve.
    • Usually negative in DFSP.
  • CD34 -ve.
    • Usually positive in DFSP.
  • D2-40 +ve.[41]
    • Usually negative in DFSP.

Ezcema

General

  • A nebulous thingy.
  • Very common.

DDx:

  • Contact allergy.
  • Drug reaction.
  • Food allergy.

Microscopic

Features:[42]

  • Spongiosis (epidermal edema); keratinocytes spacing increased - key feature.
  • +/-Interdermal vesicles.
  • +/-Eosinophils (may suggest Rx reaction).
  • Perivascular lymphocytes.

Less common

Granuloma annulare

General

  • Benign and self-limited condition.
  • Etiology unknown - may be assoc. with trauma.[43]

Microscopic

Features:[44]

  • Dermal palisading granuloma around:
    • Necrotic collagen - key feature.
      • Nuclei "missing" - have undergone karyolysis.
    • Mucin.
      • Loose/pale, paucicellular, eosinophilic.
  • Chronic inflammatory cells.

Notes:

  1. There may be multiple small foci with intervening normal dermis.[43]
  2. Granuloma annulare can be subclassified into subcutaneous and interstitial.
  3. Histomorphologically similar to Rheumatoid nodule.

DDx:

Images:

Keloid

General

  • Sites of previous trauma/surgery, esp. in dark skinned individuals.[36]

Microscopic

Features:[36]

  • Thick collagen bundles - surrounded by paler staining fibroblasts - key feature.
  • Lesion replaces adnexal structures, e.g. hair, sweat glands.

Images:

Angiofibroma

See also: nasopharyngeal angiofibroma.

General

Clinical:

  • Firm, dome-shaped, flesh coloured.

Microscopic

Features:[36]

  • Dome-shaped.
  • Fibrotic dermis.
    • Enlarged fibroblasts.
  • Dilated small vessels.

Image:

Molluscum contagiosum

General

  • Etiology: caused by molluscum contagiosum virus.

Microscopic

Features:

  • A suprabasilar epidermal lesion consisting of "molluscum bodies", i.e. molluscum bodies are found above the stratum basale.[46]
  • Molluscum bodies - key feature:
    • Large cells with abundant granular eosinophilic cytoplasm.
    • Small peripheral nucleus.

Image(s):

Notes:

  • Molluscum bodies very vaguely resemble signet ring cells -- but:
    • Cytoplasm eosinophilic and granular.
    • Nucleus usually smaller than in signet ring cell.
    • Molluscum bodies are only the epidermis - an uncommon place to find SRCs without finding them elsewhere.
  • The granular eosinophilic cytoplasm represents accumulated virons.

Syringoma

General

  • Benign sweat duct tumour.
  • Eccrine differentiation.
  • Usually close to lower eyelid.[47]

Microscopic

Features:[48]

  • Proliferation of benign ducts with lined by a bilayer (as in normal sweat ducts) with abnormal architecture:
    • Tadpole like appearing ducts.

Image:

Chondroid syringoma

  • Used to be called mixed tumour of skin.[49]

General

  • Mixed apocrine & eccrine tumour of skin, usu. in the head & neck[49], esp. nose and cheek.[50]
  • May be in major and minor salivary glands.[50]

Microscopic

Features:

  • Mix tumour with:[49]
    1. Epithelial component:
      • Nests of cells with:
        • Moderate dull eosinophilic cytoplasm.
        • Round/ovoid nuclei with nucleoli.
    2. Mesenchymal component:
      • Chondromyxoid stroma.

Dermal cylindroma

General

Microscopic

Features:

  • Nests of cells that are surrounded by hyaline (i.e. glassy, eosinophilic, acellular) material.

Images:

Keratoacanthoma

  • Abbreviated KA.
  • Generally considered to be benign.
    • Rare reports of metastases suggesting it may be a form of squamous cell carcinoma.[51]

Clinical

  • May grow rapidly (weeks or months) then involute.
  • Main DDx is squamous cell carcinoma.
  • Exophytic lesion, well-circumscribed.

Microscopic

Features:[52]

  • Expansion of stratum spinosum - pushing tongue-like downward growth of epidermis into the dermis.
  • Keratin collection (keratin plug) at the center of lesion-superficial aspect.
  • Cells have glassy pink cytoplasm.
  • Minimal/no nuclear atypia.

Image:

Superficial dermal infiltrates

Discussed in detail by Alsaad and Ghazarian.[53]

Dermal perivascular lymphoeosinophilic infiltration (DPLI)

  • Microscopic appearance is just what it is called:
    • Lymphocytes and eosinophils around the vessels in the superficial dermis.

DDx:[53]

  • Insect bite - classically wedge-shaped.[54]
  • Drug reactions.
  • Urticarial reactions.
  • Prevesicular early stage of bullous pemphigoid.
  • HIV related dermatoses.

Notes:

  • May superficially resemble cutaneous lymphoma.[54]

Images:

Congenital dermal melanocytosis

  • AKA Mongolian spots.
  • Classically seen in asian children.

Gross:

  • Brown or blue-grey patch in the lumbosacral area.

Mastocytosis

General

Classification:[55]

  1. Cutaneous (only) - usually children.
    • Urticaria pigmentosa.
    • Others.
  2. Systemic - usually adults.
    • Indolent subvariant.
    • Aggressive subvariant.
    • Leukemic subvariant.

Microscopic

Features:[56]

  • Cells in the superficial/mid dermis that are:
    • Lymphocyte-like with more cytoplasm that is granular.
      • Cells may have spindled or stellate morphology.
      • Tend to be more abundant around vessels.
  • +/-Eosinophils (common).
  • +/-Edema - often prominent; gives cells a white halo.

Notes:

  • Lymphocyte vs. mast cell:
    • Lymphocytes = round; mast cells = ovoid.

Images:

Stains

IHC

  • CD117 +ve.
  • Tryptase +ve.[57]

Ichthyosis

General

  • Comes in different flavours.
  • Usu. inherited... thus a pediatric condition.

Clinical:

  • Fish scale-like appearance.

Microscopic

Features:[56]

  • Thick stratum corneum without basket-weave pattern.

Palmar fibromatosis

General

  • AKA Dupuytren's contracture.

Clinical:[58]

  • Usually older 60-70s.
  • Male > female.
  • Associated with:
    • Alcohol abuse.
  • May be familial.

Microscopic

Features:[59]

  • Bland spindle cells in dense collagen.
    • No nuclear atypia.
  • Giant cells.
  • +/-Mitotic figures.

Images:

Angiomyoma

General

  • Benign.
  • Female > male.[61]

Microscopic

Features:

  • Well-circumscribed lesion with fascicular architecture.
  • Spindle cells/epithelioid cell with moderate eosinophilic (pink) cytoplasm.
  • Thick-walled blood vessels. (???)

Images:

Angiokeratoma

General

Notes:

Microscopic

Features:[62]

  • Ectatic superficial dermal vessels.
  • Overlying hyperkeratosis

Others: (???)

  • Irregular acanthosis.
  • Longer rete ridges.

Images:

DDx:

Inverted follicular keratosis

General

  • Benign skin lesion.
  • Central face - middle age.[63]
  • Uncommon.

Clinical DDx:[63][64]

Microscopic

Features:[63]

  • Keratinocyte of cytologically benign proliferation.
  • "Squamous eddies" (whorls of keratin).
  • Coarse keratohyaline granules.

DDx:

Images:

Panniculitis

This is dealt with in the panniculitis article.

DDx for panniculitis:

Rare

Porokeratosis

General

  • Genetic.
  • Several subtypes.

Notes:

  • Not the same as punctate porokeratotic keratoderma.[65]

Microscopic

Features:

  • Cornoid lamella (pathognomonic) - key feature:
    • Compact keratosis over a hair follicle.
  • +/-Rete ridge loss.

Nevus sebaceous

  • AKA nevus sebaceous of Jadassohn.

General

  • Congenital.
  • Face or scalp.

Microscopic

Features:

  • Abundant sebaceous glands.

Bullous disease

Cysts

See also

References

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