Non-malignant skin disease

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 skin conditions are dealt with in inflammatory skin disorders.

Other

Lichen simplex chronicus

Main article: Lichen simplex chronicus

Prurigo nodularis

• Abbreviated PN.
• AKA chronic prurigo and picker nodule.

General

• Can be thought of as a localized/focal version of lichen simplex chronicus (LSC).

Gross

• Dome-shaped/raised - papular (<1 cm) or nodular (>1 cm).

Microscopic

• See lichen simplex chronicus.

DDx:

• Lichen simplex chronicus - a more diffuse process, not a raised lesion.

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SKIN LESION, LEFT CHIN, BIOPSY: 
- PRURIGO NODULARIS.

Micro

The sections show a raised lesion with compact hyperkeratosis and irregular acanthosis. Spongiosis is seen focally. There is minimal hypergranulosis.

There is no thinning of the suprapapillary plate and no dilated superficial blood vessels. There is no interface activity.

Very common

Dermatomycosis

Dermatophytosis redirects here.

General

• Fungal infection of skin.

Note:

• Dermatophytosis (ring worm) is a type of dermatomycosis.

Microscopic

Features:

• Microorganisms - key feature.
  • Often hyphae (candida) - like twigs of a tree... branching.
    • May be very fragmented in section ~ size of a neutrophil.
• Perivascular inflammation, esp. neutrophils.
• Exocytosis - blood cell infiltrate the epidermis.

Images:

• WC:
  • Dermatomycosis - intermed. mag. (WC).
  • Dermatomycosis - high mag. (WC).
  • Dermatomycosis - GMS stain - low mag. (WC).
  • Dermatomycosis - GMS stain - high mag. (WC).
• www:
  • Dermatophytosis (ucsf.edu).

Stains

• GMS stain.
• PAS-D stain.

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SKIN, BIOPSY:
- SKIN WITH SUPERFICIAL FUNGAL ORGANISMS CONSISTENT WITH CANDIDA.
- REACTIVE CHANGES OF THE EPITHELIUM.

Micro

The sections show skin with a neutrophilic infiltrate in the superficial epidermis. PAS-D staining demonstrates fungal organisms with a morphology suggestive of candida.

The epithelium has parakeratosis, acanthosis and spongiosis. No mitotic activity is appreciated. The keratinocytes are moderately enlarged and have evident nucleoli.

Cicatrix

Main article: Dermal scar

Fibroepithelial polyp

Main article: Fibroepithelial polyp

Actinic keratosis

Main article: Actinic keratosis

Actinic cheilitis

General

• Actinic keratosis of the lip.

Microscopic

See actinic keratosis.

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LESION, LOWER LIP, BIOPSY: 
- ACTINIC CHEILITIS.
- SOLAR ELASTOSIS.

Micro

The sections show skin with moderate basal nuclear hyperchromasia and atypia, and parakeratosis. The squamous epithelium has maturation to the surface. There is no inflammation at the dermal-epidermal interface. Solar elastosis is present.

Seborrheic keratosis

Main article: Seborrheic keratosis

Pilomatricoma

Main article: Pilomatricoma

Dermatofibroma

Main article: Dermatofibroma

Ezcema

General

• A nebulous thingy.
• Very common.

DDx:

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

Microscopic

Features:

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

Acne vulgaris

General

• Extremely common - esp. among adolescents.
• Very rarely seen by pathologists.

Treatments:

• Antibiotic (minocycline).
• Isotretinoin AKA all-trans retinoic acid (ATRA).

Gross

• Papules, pustules, nodules or cysts.
  • White, black or erythematous.

Images:

• Blackheads (WC).

Microscopic

Features:

• Folliculitis:
  • Neutrophils around hair follicle and infiltrate into it - including the follicular canal.
• Epidermal invagination or cyst at site of a hair follicle - contains:
  • Sebum.
  • +/-Bacteria (Propionibacterium acnes) and inflammatory cells - typically neurophils.

Subtyped into:

1. Open comedones ("blackheads") - no extension to epidermal surface.
2. Closed comedones ("whiteheads") - to epidermal surface have wide opening.

DDx - acneiform disorder:

• Rosacea.
• Infective folliculitis.
• Perioral dermatitis.
• Acne vulgaris.

Image:

• Acne (dermnet.com).

Solar elastosis

• AKA actinic elastosis.

General

• Very common.
• Caused by sun exposure - specifically UV light.
  • Severity correlated with cumulative exposure to UV light..
• Often co-localized with skin cancers - as UV light is risk factor for skin cancers.
• Benign.

Microscopic

Features:

• Grey, spaghetti-like material in the superficial dermis.

DDx:

• Actinic keratosis.
• Basal cell carcinoma.
• Squamous cell carcinoma.

Note:

• The DDx above is things associated with sun damaged skin.
• Dermal mucin (as my be seen in lupus erythematosus) is a possible mimic - but it isn't spaghetti-like and the "background" (an interface dermatitis) is different.

Images

• 

  Solar elastosis - intermed. mag. (WC)

• 

  Solar elastosis - high mag. (WC)

www:

• Solar elastosis - several images (dermpathexpert.com).

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SKIN, RIGHT CHEEK, RE-EXCISION:
- DERMAL SCAR.
- EXTENSIVE SOLAR ELASTOSIS.

Prominent blood vessels

SKIN LESION, LEFT CHEEK, BIOPSY:
- SKIN WITH SOLAR ELASTOSIS AND PROMINENT SMALL BLOOD VESSELS.

SUPERIOR SHOULDER, LEFT, PUNCH BIOPSY:
- BENIGN SKIN WITH MODERATE SOLAR ELASTOSIS, PROMINENT SMALL BLOOD VESSELS AND
  SCATTERED PERIVASCULAR LYMPHOCYTES AND PLASMA CELLS.
- NEGATIVE FOR BASAL CELL CARCINOMA.
- NEGATIVE FOR ACTINIC KERATOSIS.

Micro

The sections show hair bearing skin with solar elastosis and numerous small dilated blood vessels. The dermis is mildly fibrotic. Compact keratin is present.

The epidermis matures to the surface. A granular layer is present. There is no basal epidermal atypia. No melanocytic nests are identified. There is no palisading of the basal cells. Rare scattered lymphocytes are in the dermis.

Very common - viral

Verruca vulgaris

Main article: Verruca vulgaris

Verruca plana

General

• Common.
• Usu. hands and face.

Microscopic

Features:

• Orthokeratosis with basketweave pattern.
• Hypergranulosis.
• Viral keratohyaline.
• Koilocytes.
• Acanthosis - yet flat surface and base.

Notes:

• It differs from verruca vulgaris... (1) orthokeratosis, (2) flat surface and base.

Images:

• Verruca plana - several images (fujita-hu.ac.jp).
• Verruca plana (convdocs.org).
• Verruca plana - several good images (dermatopathonline.com).

Less common

Chronic folliculitis

Folliculitis redirect here.

General

• Common.
• Infrequently biopsied.

Gross

• Erythema.

DDx gross:

• Melanocytic lesions.

Microscopic

Features:

• Inflammation around the hair follicle - key feature.
  • Lymphocytes - usu. predominant.
• +/-Chronic changes:
  • Acanthosis.
  • Hyperkeratosis.
  • Hypergranulosis.

DDx:

• Acne vulgaris.

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SKIN LESION, UPPER ARM, BIOPSY:
- CHRONIC FOLLICULITIS WITH SECONDARY SURFACE CHANGES.

Micro

The sections show hair-bearing skin with abundant lymphocytes around and within the hair follicle wall.

The non-hair follicle epidermis has acanthosis, hypergranulosis and compact hyperkeratosis. There is no inflammatory cell infiltrate in the non-hair follicle epidermis or at the non-hair follicle interface.

There are no granulomas.

Clear cell acanthoma

General

• Benign.
• Elderly.
• Classically on the leg.
• Rare.
• Clinically not distinct.
  • Suspected clinically in only ~3% of cases.

Microscopic

Features:

• Psoriasiform pattern - epidermal thickening (acanthosis).
• Keratinocytes:
  • Pale or light pink cytoplasm (when compared to surrounding non-lesional keratinocytes).
  • Separated from one another (spongiosis).
• +/-Stratum corneum neutrophils.

DDx:

• Psoriasis vulgaris.

Images:

• CCA (drmihm.com).
• CCA - low mag. (dermatlas.com).
• CCA - high mag. (dermatlas.com).

Chondrodermatitis nodularis chronica helicis

• AKA chondrodermatitis nodularis helicis.
• Abbreviated CNCH.

General

• Tender/painful - key clinical feature.
• Typically right ear - people more often sleep on this one.
• Usually >40 years old.

Etiology:

• Trauma/mechanical.

Gross

• Papule on ear.
• +/-Erythematous.
• +/-Crust.

Clinical DDx:

• BCC.
• SCC.

Images:

• CNCH (WC).
• CNCH (dermnetnz.org).

Microscopic

Features:

• Dermal inflammation.
• Epithelial hyperlasia.
• Fibrosis.
• Cartilaginous pathology:
  • Perichondrial inflammation - key feature.
  • Perichondrial disruption.
  • +/-Necrosis.
  • +/-Hemorrhage.

Images:

• CNCH (dermpedia.org).
• CNCH (surgicalpathologyatlas.com).
• CNCH (dermatlas.med.jhmi.edu).

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Superficial biopsy

SKIN LESION, LEFT ANTIHELIX OF EAR, BIOPSY:
- SUPERFICIAL SKIN WITH ACANTHOSIS, HYPERKERATOSIS, MODERATE SOLAR ELASTOSIS, 
  HYPERGRANULOSIS AND A MILD LYMPHOCYTIC PERIVASCULAR INFILTRATE.
- NO CARTILAGE IS IDENTIFIED.
- NEGATIVE FOR DYSPLASIA AND MALIGNANCY.

COMMENT:
The findings are non-specific. Chondrodermatitis cannot be excluded.

Cutaneous calcinosis

• AKA calcinosis cutis.

General

• Benign in itself; underlying cause may not be benign.
• May be a scrotal lesion - known as scrotal calcinosis.

Subtypes:

1. Dystrophic - due to death of cells; may be related to a tumour.
2. Metastatic - due to chronic renal failure; hyperkalemia; paraneoplastic phenomenon.
3. Iatrogenic - post surgical.
4. Idiopathic.

Microscopic

Features:

• Dermal calcification:
  • Acellular purple blobs on H&E.
    • +/-Artefactual tearing of surrounding tissue due to processing (cutting).
    • +/-Small artefactual lines ~1-2 micrometers due to processing (cutting).
    • +/-Greyish rim of paucicellular material.
  • Usu. well-circumscribed.
    • May be surrounded by a palisading granuloma & giant cells.

Images:

• Calcinosis cutis (dermatopathonline.com).

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SKIN AND SUBCUTANEOUS LESION, LEFT HIP, EXCISION:
- SUBCUTANEOUS CALCIFICATION SURROUNDED BY BENIGN FIBROUS TISSUE.
- DERMAL SCAR.
- NEGATIVE FOR MALIGNANCY.

SUBCUTANEOUS MASS, OVER BURSA OF ELBOW, EXCISION:
- CALCINOSIS CUTIS.

Micro

The sections show subcutaneous calcifications surrounded by macrophages and giant cells. No nuclear atypia is apparent. The overlying skin is unremarkable.

Dilated pore of Winer

General

• Benign.
• Looks like zit.

Microscopic

Features:

• Dilated hair follicle with keratin.
• Acanthosis.
• Budding of epidermis (into dermis).

DDx:

• Pilar sheath acanthoma.

Image:

• Dilated pore of Winer (dermpathexpert.com).

Lichenoid keratosis

• AKA lichen planus-like keratosis.
• AKA lichenoid keratosis.

General

• Caucasians - middle age or older.
• May be a variant of seborrheic keratosis (with marked inflammation).

Clinical DDx:

• Basal cell carcinoma, squamous cell carcinoma of the skin, melanocytic neoplasm.

Microscopic

Features:

• Hyperkeratosis.
• Parakeratosis.
• Band of inflammatory cells at DE junction (lichenoid inflammation).
• Dead keratinocytes (Civatte bodies).
• Dermal melanophages.

DDx:

• Lichen planus - need clinical correlation (mucosal lesions).
• Drug reaction.
• Cutaneous T-cell lymphoma.
• Regressed melanocytic lesion, esp. malignant melanoma.
• Lichenoid actinic keratosis - has atypical hyperchromatic basal cells - esp. at edge of lesion, usu. in the context of solar elastosis.

Images:

• Lichenoid keratosis (dermpathexpert.com).

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SKIN LESION, MID-MIDDLE BACK, PUNCH BIOPSY:
- LICHENOID KERATOSIS.

Incompletely excised

SKIN LESION, LEFT CHEST, PUNCH BIOPSY:
- LICHENOID KERATOSIS VERSUS ACTINIC KERATOSIS.
- NEGATIVE FOR BASAL CELL CARCINOMA.
- SEE COMMENT.

COMMENT:
No eosinophils are apparent. No melanocytic lesion is identified; however, excision of the
whole lesion to exclude a partially regressed melanocytic lesion is suggested.

Granuloma annulare

Main article: Granuloma annulare

Necrobiosis lipoidica

Main article: Necrobiosis lipoidica

Keloid

Main article: Keloid

Angiofibroma

See also: nasopharyngeal angiofibroma.

Should not be confused with angiokeratoma.

General

• May be seen in the context of tuberous sclerosis - especially "butterfly area of the face".
• Solitary lesions in adults are known as fibrous papules and classically arise on the nose.

Clinical:

• Firm, dome-shaped, flesh coloured.

Microscopic

Features:

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

DDx:

• Benign fibrous papule - solitary, nose lesion.

Image:

• Angiofibroma (drdittmar.lu).

Benign fibrous papule

• AKA fibrous papule.

General

• An angiofibroma on the face that is solitary.

Gross

• Solitary lesion of the face - important.
  • Usually on the nose.

Microscopic

Features:

• Dome-shaped.
• Fibrotic dermis.
  • Enlarged fibroblasts.
• Dilated small vessels.
• +/-Multinucleated stromal cells.
• +/-Stellate cells.

DDx:

• Angiofibroma - not solitary or not on the nose.

Note:

• Several variants exist.

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SKIN LESION, CHIN, BIOPSY:
- BENIGN FIBROUS PAPULE.

Molluscum contagiosum

Main article: Molluscum contagiosum

Superficial dermal infiltrates

Discussed in detail by Alsaad and Ghazarian.

Dermal perivascular lymphoeosinophilic infiltration

• Abbreviated DPLI.

Microscopic appearance is just what it is called:

• Lymphocytes and eosinophils around the vessels in the superficial dermis.

DDx:

• Insect bite - classically wedge-shaped.
• Drug reaction.
• Urticarial reaction.
• Prevesicular early stage of bullous pemphigoid.
• HIV related dermatoses.

Notes:

• May superficially resemble cutaneous lymphoma.

Images:

• DPLI - very low mag. (WC).
• DPLI - very high mag. (WC).

Congenital dermal melanocytosis

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

Gross:

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

Mastocytosis

General

• Abundance of mast cells.

Classification:

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

Microscopic

Features:

• 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:

• www:
  • Mastocytosis - low res. (jameswpattersonmd.com).
  • Mastocytosis - bone marrow - several images (upmc.edu).
• WC:
  • Mastocytosis - high mag. (WC).
  • Mastocytosis - very high mag. (WC).
  • Systemic mastocytosis - several images (upmc.edu).

Stains

• Toluidine blue -- highlights the granules.

IHC

• CD117 +ve.
• Tryptase +ve.

Ichthyosis

General

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

Gross

• Fish scale-like appearance.

Image:

• Ichtyosis (WC).

Microscopic

Features:

• Thick stratum corneum without basket-weave pattern.

Palmar fibromatosis

• AKA Dupuytren's contracture.
• AKA Dupuytren disease.

Main article: Palmar fibromatosis

Angiomyoma

• Do not confuse with angiomyxoma.

General

• Benign.
• Female > male.

Microscopic

Features:

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

Images:

• Angiomymoma (WC).
• Angiomymoma (WC).

Angiokeratoma

General

• Rare.
• May be seen in the context of Fabry disease.

Notes:

• Shouldn't be confused with angiofibroma which is associated tuberous sclerosis.

Gross

• Dark lesions.

Clinical DDx:

• Melanocytic lesions.

Images

• 

  Angiokeratoma. (WC)

Microscopic

Features:

1. Ectatic superficial dermal vessels.
2. Overlying hyperkeratosis (thick stratum corneum).

• Should have "epidermal collarette".
  • Vascular space surrounded by epidermis on three sides.

Others features:^{[citation needed]}

• Irregular acanthosis.
• Longer rete ridges.

DDx:

• Venous lake.

Images

• 

  Angiokeratoma - low mag. (WC/Nephron)

• 

  Angiokeratoma - intermed. mag. (WC/Nephron)

www:

• Angiokeratoma (pathologyoutlines.com).

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SKIN LESION, LEFT POPITEAL FOSSA, PUNCH BIOPSY:
- ANGIOKERATOMA.

Inverted follicular keratosis

• Abbreviated IFK.

General

• Benign skin lesion.
• Central face - middle age.
• Uncommon.
• May be considered a variant of seborrheic keratosis that is predominantly endophytic.

Clinical DDx:

• BCC.
• Wart.

Microscopic

Features:

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

DDx:

• Squamous cell carcinoma of the skin.
• Trichilemmoma.
• Seborrheic keratosis - has an exophytic component.

Images:

• Inverted follicular keratosis - low mag. (flickr.com).
• Inverted follicular keratosis - high mag. (flickr.com).
• Inverted follicular keratosis - several images (mckeedermpath.com).

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SKIN LESION, FACE, BIOPSY:
- INVERTED FOLLICULAR KERATOSIS.

Micro

The sections show skin with acanthosis, pseudohorn cysts, and focal basal epidermal pigmentation. There is no basal nuclear atypia, no mitoses and there are no melanocytic nests. There is minimal dermal inflammation. There is no apparent solar elastosis.

Focal cutaneous mucinosis

General

• Benign.
• May be associated with systemic disease.

Microscopic

Features:

• Light blue whispy material in the dermis - key feature.

DDx:

• Dermal edema.
• Digital mucous cyst.

Panniculitis

Main article: Panniculitis

This is dealt with in the panniculitis article.

DDx for panniculitis:

• Erythema nodosum.
• Erythema induratum.
• Self-inflicted trauma.
• Systemic lupus erythematosus.
• Weird stuff.

Rare

Necrotizing fasciitis

Not to be confused with nodular fasciitis.

• AKA flesh-eating disease.

General

• High mortality.
• May be diagnosed at frozen section.
• Classically associated with Group A streptococcus.

Treatment:

• Operative debridement.

Microscopic

Features:

• Necrosis of fascia - key feature.
  • PMNs and necrotic debris (amorphous grey or pink material).

Note:

• Fat lobules between septae may be normal.

DDx:

• Cellulitis.

Images:

• Necrotizing fasciitis - intermed. mag. (WC).
• Necrotizing fasciitis - high mag. (WC).

Porokeratosis

General

• Genetic.
• Several subtypes.

Notes:

• Not the same as punctate porokeratotic keratoderma.

Microscopic

Features:

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

Images

• 

  Porokeratosis - intermed. mag. (WC)

• 

  Porokeratosis - very high mag. (WC)

Nevus sebaceous

• AKA nevus sebaceous of Jadassohn.

General

• Congenital - considered a hamartoma.
• Usually sporadic - may be transmitted autosomal dominant.
• Malignant tumours may arise within a nevus sebaceous.

Gross

Features:

• Head and neck plaque or papule with:
  • Well-circumscribed borders.
  • Waxy, yellow appearance.
• Area usu. devoid of hair.

DDx - gross:

• Seborrheic keratosis.

Image:

• NS (dermnet.com).

Microscopic

Features:

• Abundant sebaceous glands.
• Immature/abortive hair follicles.
  • No normal terminal hair follicles.
• Papillomatous epidermal hyperplasia.

Images:

• NS (WC).
• NS (dermnet.com).

Nevus lipomatosus superficialis

• Abbreviated NLS.
• AKA nevus lipomatosus cutaneous superficialis, abbreviated NLCS.
• AKA nevus lipomatosus.

General

• Rare.
• Congenital - considered a hamartoma.
• Usually young adults.

Clinically separated into:

• Solitary - one lesion.
• Multiple - more than one lesion.

Gross

Features:

• Pedunculated lesion.
• Soft.
• Usually lower trunk or gluteal region.

Image:

• NLS (nih.gov).

Microscopic

Features:

• Benign adipose tissue in the dermis.
  • Adipocytes in reticular dermis +/- papillary dermis.

DDx:

• Lipoma.
• Fibroepithelial polyp (skin tag).
• Intradermal nevus with adipocytes.

Images:

• NLS (dermamin.com).
• NLS (humpath.com).
• NLS (nih.gov).
• Nevus lipomatosus (dermpedia.org).

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SKIN LESION ("SKIN TAG"), LEFT HIP, EXCISION:
- NEVUS LIPOMATOSUS SUPERFICIALIS.

Bullous disease

Main article: Bullous disease

Cysts

Main article: Dermal cysts

See also

• Dermatopathology introduction.
• Malignant skin disease.