Superficial Fungal Infections

Slide 1 · Superficial Fungal Infections

Clinicopathologic patterns of dermatophytoses and tinea versicolor

Cutaneous localization · Lesion morphology · Fungal demonstration

Dr Abu Suraih Sakhri

MBBS, MD (Pathology)

www.abusuraihsakhri.com

Slide 2 · Learning objectives

Distinguish dermatophytoses by involved anatomic site and characteristic clinical pattern.

Explain which tissue compartment contains organisms and how the epidermis may react.

Interpret PAS positivity and the role of culture in identifying the fungus.

Recognize why tinea versicolor is etiologically distinct from dermatophytoses.

Slide 3 · The defining compartment is superficial

Superficial mycoses with deep cutaneous fungal infections.

Superficial infections largely involve cornified keratinized tissue; Deep infections primarily involve dermis or subcutis.

The anatomic depth helps frame what a biopsy or scraping must demonstrate.

Anucleate stratum corneum

Viable epidermis

Dermis

Subcutaneous plane (context)

Schematic — not a clinical or histologic specimen

Slide 4 · Keratinized sites link the clinical syndromes

Superficial fungi are demonstrable in cornified lesional skin, hair, or nails.

The affected structure determines the familiar tinea site designation.

Organism location and the host inflammatory response are separate microscopic observations.

SKIN

Stratum corneum

HAIR

Keratinized shaft

NAIL

Nail plate

Lesional sampling follows the affected keratinized structure

Slide 5 · Dermatophytes are the principal agents

Dermatophytes as the primary cause of superficial fungal skin infection.

Dermatophytes may inhabit soil and animals.

Tinea versicolor is a stated exception: Its agent is a yeast, not a dermatophyte.

Superficial fungal syndromes

Dermatophytes

Malassezia yeast

Site-defined tinea patterns

Tinea versicolor

Conceptual grouping — not a phylogenetic tree

Slide 6 · Clinical names map to anatomic sites

Capitis denotes the scalp; Barbae, the beard area; Corporis, non-specialized body skin.

Cruris refers to the groin; Pedis to the feet.

Onychomycosis denotes fungal nail infection; Versicolor denotes a distinctive pigmentary macular eruption.

Scalp

Capitis

Beard

Barbae

Body skin

Corporis

Groin

Cruris

Feet

Pedis

Nail

Onychomycosis

Slide 7 · Distribution is a first diagnostic clue

Scalp disease directs attention to capitis; Beard-area disease suggests barbae.

Expanding body plaques suggest corporis; Moist inguinal patches suggest cruris.

Interdigital scaling suggests pedis; Upper-trunk multicolored macules suggest versicolor.

Scalp

Capitis

Beard

Barbae

Body skin

Corporis

Groin

Cruris

Feet

Pedis

Nail

Onychomycosis

Slide 8 · Site and morphology should be read together

Pattern

Typical site

Dominant clinical clue

Capitis

Scalp

Patchy scale ± hair loss

Corporis

Body skin

Expanding, scaly-edged plaque

Cruris

Upper inner thigh/groin

Moist erythematous patch

Pedis

Feet, often web spaces

Erythema with scale

Versicolor

Upper trunk

Variably colored fine-scaled macules

Slide 9 · The clinical pattern is not the fungal species

The tinea names in this section are primarily anatomic or morphologic.

Different appearances may share superficial tissue localization.

Culture, rather than clinical pattern alone, usually permits identification of the offending dermatophyte species.

Anatomic site

Morphology

Culture for species

Clinical → anatomic / tissue evidence → identification

Slide 10 · Tinea capitis: Infection of the scalp

Tinea capitis is dermatophytosis involving the scalp.

Patchy scalp lesions rather than a single defining gross configuration.

Mild erythema, scaling, and crusts may accompany hair loss.

Hair shafts

Scalp surface: Patchy scale

Schematic — not a clinical or histologic specimen

Slide 11 · Tinea capitis predominantly affects children

Tinea capitis usually occurs in children.

It is encountered only rarely in infants and adults in the cited description.

Age and location together sharpen clinical suspicion.

Usual clinical setting

– Child with scalp changes

– Scaling or patchy lesions

Less frequent in source

– Infant with scalp lesions

– Adult with scalp lesions

Slide 12 · Tinea capitis: The lesion may be subtle

The scalp patches may be asymptomatic.

Mild redness and superficial crust can coexist with scale.

Absence of prominent discomfort does not contradict the textbook phenotype.

Hair shafts

Scalp surface: Patchy scale

Schematic — not a clinical or histologic specimen

Slide 13 · Scalp scale, crust, and erythema

Scale points to involvement of the epidermal cornified layer.

Crust formation and mild erythema are described clinical components.

The relative prominence of each feature can vary across clinical cases.

Hair shafts

Scalp surface: Patchy scale

Schematic — not a clinical or histologic specimen

Slide 14 · Hair loss changes the diagnostic emphasis

Hair loss is frequent account of capitis.

A patchy alopecic scalp lesion accompanied by scale should prompt consideration of scalp dermatophytosis.

Inspection should encompass both scalp surface and hair-bearing region.

Patchy visible hair loss

Schematic — not a clinical or histologic specimen

Slide 15 · Hair loss versus scale: Complementary clues

Scale reflects the superficial cutaneous presentation.

Alopecia reflects clinical involvement of the hair-bearing scalp.

Neither feature alone determines the particular dermatophyte species.

Surface finding

– Fine or overt scaling

– Mild erythema

– Crust formation

Hair-related finding

– Patchy hair loss

– Hair-bearing scalp distribution

– Use both in interpretation

Slide 16 · Teaching case: Patchy scalp alopecia

A school-aged child has irregular patches of hair loss with overlying scale and mild redness.

Which anatomic tinea diagnosis best fits the source phenotype?

What feature distinguishes this presentation from a scaly plaque on non-hair-bearing body skin?

HYPOTHETICAL TEACHING CASE

A school-aged child has irregular patches of hair loss with overlying scale and mild redness.

Discuss the question and justify the distinguishing features.

Slide 17 · Tinea barbae: The beard-area pattern

Tinea barbae is a dermatophyte infection involving the beard region.

It is relatively uncommon description.

Unlike capitis, its anatomic designation is specific to the beard area.

Localization: Beard-bearing skin

Schematic — not a clinical or histologic specimen

Slide 18 · Host context in tinea barbae

The described patient group is adult males.

The beard region is the key localization clue.

The textbook section gives fewer specific lesion details for barbae than for corporis or cruris.

Localization: Beard-bearing skin

Schematic — not a clinical or histologic specimen

Slide 19 · Capitis and barbae: Similar name, different site

Feature

Tinea capitis

Tinea barbae

Localization

Scalp

Beard area

Usual group described

Children

Adult males

Frequency in excerpt

Common childhood syndrome

Relatively uncommon

Characteristic detail

Patchy scale and hair loss

Site-based designation

Slide 20 · Tinea corporis occurs across the lifespan

Tinea corporis is a common superficial fungal infection of skin.

Involvement at all ages, especially children.

The clinical pattern is an expanding round plaque with a recognizable scaling border.

Expanding round plaque

Schematic — not a clinical or histologic specimen

Slide 21 · Environmental factors in tinea corporis

Excessive heat predisposes to tinea corporis.

Humidity is another risk factor cited.

These conditions are interpreted with skin findings rather than serving as diagnostic criteria alone.

Heat

+

Humidity

+

Animal exposure

Predisposition / clinical context

Slide 22 · Animal exposure is a clinical history clue

Exposure to infected animals as a predisposing factor.

The source also notes that dermatophytes can grow on animals and in soil.

Exposure history is supportive but not a substitute for observing the characteristic lesion.

Soil habitat

Animal habitat

Animal exposure: Corporis risk

Separate habitats and exposure information; No inferred transmission sequence

Slide 23 · Feet and nails may coexist with corporis

Chronic dermatophytosis of the feet or nails predisposes to tinea corporis.

A focused examination can therefore include these additional keratinized sites.

This relationship is clinical context; It does not identify a particular fungal species.

Chronic foot dermatophytosis

Nail involvement / onychomycosis

Both may be associated with predisposition to tinea corporis

Relationship is clinical; Arrow does not establish individual transmission

Slide 24 · Tinea corporis has an expanding plaque

An expanding, round, slightly erythematous plaque.

Recognition depends on overall configuration and the lesion border.

The border is raised and scaling in the characteristic presentation.

Expanding round plaque

Schematic — not a clinical or histologic specimen

Slide 25 · The active-looking border is the key feature

Peripheral scaling and elevation distinguish the classic corporis plaque.

An expanding circular pattern is highly characteristic in the source account.

A native schematic shows the described shape, not an actual patient lesion.

Expanding round plaque

Schematic — not a clinical or histologic specimen

Slide 26 · Why the plaque edge matters to the examiner

The raised scaly circumference is a more specific clue than redness alone.

The same source separately describes macular fine-scaled versicolor lesions.

Pattern recognition should connect shape, scale, and site.

Corporis

– Expanding round plaque

– Raised scaling edge

– Slight erythema

Versicolor

– Multiple macules

– Variable colors

– Fine peripheral scale

Slide 27 · Teaching case: An annular plaque

A child has a gradually enlarging round plaque on the arm, with a slightly raised scaly edge.

Which source-described tinea pattern does this most closely match?

Which three lesion descriptors are decisive?

HYPOTHETICAL TEACHING CASE

A child has a gradually enlarging round plaque on the arm, with a slightly raised scaly edge.

Discuss the question and justify the distinguishing features.

Slide 28 · Tinea cruris localizes to the inguinal region

Cruris refers to infection of the groin and upper inner thighs.

Initial lesions on the upper inner thighs.

Site is essential because moist erythematous patches also occur in other settings.

Upper inner thighs / inguinal folds

Schematic — not a clinical or histologic specimen

Slide 29 · Tinea cruris: Typical clinical context

Greater frequency in obese males.

Warm weather is highlighted as a common circumstance.

The associated local environment contributes to the clinical pattern.

Obesity

+

Warm weather

+

Heat / friction

Predisposition / clinical context

Slide 30 · A triad predisposes to tinea cruris

Heat, friction, and maceration are explicitly listed as predisposing factors.

These factors are particularly relevant at opposed skin surfaces.

The clinical picture includes moist red patches and a raised scaly margin.

Heat

+

Friction

+

Maceration

Predisposition / clinical context

Slide 31 · Tinea cruris: Morphology of the patch

The earliest described lesions are moist, red patches.

Raised scaling borders remain important recognition features.

The upper inner-thigh origin distinguishes cruris from a generic body plaque.

Upper inner thighs / inguinal folds

Schematic — not a clinical or histologic specimen

Slide 32 · Corporis versus cruris: Location modifies the pattern

Feature

Tinea corporis

Tinea cruris

Typical location

Body skin

Inguinal region / inner thigh

Configuration

Round expanding plaque

Moist red patch

Edge

Raised and scaling

Raised and scaling

Predisposing context

Heat; humidity; animals; chronic foot/nail infection

Warm weather; heat; friction; maceration

Slide 33 · Tinea pedis is a common exposure over a lifetime

30%–40% of people are affected at some point in life.

This is a lifetime-occurrence statement, not a point-prevalence estimate.

The commonness of pedis makes careful differentiation of its components important.

30%–40%

Affected at some time in life (Robbins)

Lifetime occurrence — not point prevalence

Slide 34 · Tinea pedis often begins in toe web spaces

Diffuse erythema and scaling characterize the textbook presentation.

The findings are frequently first localized to the web spaces.

Inspection limited to plantar skin could overlook early interdigital disease.

Scale often begins between toes

Schematic — not a clinical or histologic specimen

Slide 35 · Pedis: Erythema and scaling coexist

Erythema can accompany widespread scaling.

The source describes the distribution as potentially diffuse.

Clinical inflammation does not automatically reflect fungal burden alone.

Scale often begins between toes

Schematic — not a clinical or histologic specimen

Slide 36 · Bacterial superinfection modifies tinea pedis

Much of the inflammatory reaction to bacterial superinfection.

The visible inflammation may therefore not be directly caused by the primary dermatophytosis.

This distinction matters when correlating clinical inflammation with fungal histology.

Primary dermatophyte process

Variable host epidermal response

Possible bacterial superinfection

Interpret fungal localization and inflammation separately

Slide 37 · Tinea pedis: Separate primary and secondary effects

Primary process: Superficial dermatophyte infection in foot skin.

Secondary process: Bacterial superinfection may account for much of the inflammation.

The two processes should not be treated as equivalent explanations.

Primary dermatophyte process

Variable host epidermal response

Possible bacterial superinfection

Interpret fungal localization and inflammation separately

Slide 38 · Onychomycosis is infection of the nail

Fungi may spread from tinea pedis to nails; Nail infection may also arise primarily.

The term onychomycosis describes fungal infection of nail structures.

Clinical alteration of the nail plate is characteristic in the cited description.

Discoloration • thickening • deformation

Schematic — not a clinical or histologic specimen

Slide 39 · Nail discoloration is one sign

Altered nail color in onychomycosis.

Color change should be interpreted together with thickening or deformity.

Nail involvement is also relevant when assessing possible associated tinea corporis.

Discoloration • thickening • deformation

Schematic — not a clinical or histologic specimen

Slide 40 · Thickening and deformity of the nail plate

Thickening is a second characteristic nail change.

Deformity reflects loss of the nail plate’s usual shape.

The findings are a morphologic clinical description, not species-level identification.

Discoloration • thickening • deformation

Schematic — not a clinical or histologic specimen

Slide 41 · Foot and nail disease form a connected clinical picture

A foot infection can extend to the nail.

Primary infection of the nail is also possible.

Chronic foot or nail dermatophytosis is an identified predisposing context for corporis.

Chronic foot dermatophytosis

Nail involvement / onychomycosis

Both may be associated with predisposition to tinea corporis

Relationship is clinical; Arrow does not establish individual transmission

Slide 42 · Tinea versicolor has a different fungal agent

Tinea versicolor is caused by Malassezia furfur.

The agent is a yeast, explicitly not a dermatophyte.

Grouping this condition among superficial mycoses does not make it a dermatophytosis.

Superficial fungal syndromes

Dermatophytes

Malassezia yeast

Site-defined tinea patterns

Tinea versicolor

Conceptual grouping — not a phylogenetic tree

Slide 43 · Upper trunk is the classic versicolor site

A usual location on the upper trunk.

Lesions appear in groups rather than as one expanding annular plaque.

Anatomic distribution and lesion shape are both useful clinical distinctions.

Upper trunk: Grouped macules of varied color

Schematic — not a clinical or histologic specimen

Slide 44 · Macules of varied color define versicolor

Individual macules vary in size and color.

The mixture of tones produces the clinical description “versicolor.”

These are macules rather than raised annular plaques in the source account.

Upper trunk: Grouped macules of varied color

Schematic — not a clinical or histologic specimen

Slide 45 · Fine peripheral scale completes the pattern

The textbook specifically mentions a fine scale at the lesion periphery.

Versicolor combines multiple macules, varied pigmentation, and fine scaling.

The appearance contrasts with the elevated scaly border of tinea corporis.

Upper trunk: Grouped macules of varied color

Schematic — not a clinical or histologic specimen

Slide 46 · Dermatophyte versus Malassezia syndromes

Feature

Dermatophytoses

Tinea versicolor

Agent category

Dermatophytes

Malassezia furfur (yeast)

Common site labels

Capitis, barbae, corporis, cruris, pedis

Upper trunk predominance

Illustrative lesion

Annular corporis plaque

Mixed-color macules

Scale feature

Often raised scaling edge in corporis/cruris

Fine peripheral scale

Slide 47 · Histology is variable rather than pathognomonic on H&E

The histologic appearance of dermatophytosis varies.

Organism characteristics, host response, and bacterial superinfection all contribute.

Routine inflammatory findings alone need not identify the infecting fungal organism.

Primary dermatophyte process

Variable host epidermal response

Possible bacterial superinfection

Interpret fungal localization and inflammation separately

Slide 48 · The stratum corneum is the critical microscopic site

Fungal elements are described in the anucleate cornified layer.

The same principle extends to infected hair and nails.

The figure’s scale is conceptual; It is

Anucleate stratum corneum

Viable epidermis

Dermis

Subcutaneous plane (context)

Schematic — not a clinical or histologic specimen

Slide 49 · A spongiotic reaction may accompany fungi

A mild eczematous (spongiotic) dermatitis.

Spongiosis is part of the host epidermal reaction.

Fungal organisms must still be demonstrated to substantiate dermatophytosis.

Anucleate stratum corneum

Viable epidermis

Dermis

Subcutaneous plane (context)

Schematic — not a clinical or histologic specimen

Slide 50 · Intraepidermal neutrophils may be present

Intraepidermal neutrophils and focal neutrophilic abscesses.

This inflammatory pattern is not presented as uniformly present in every case.

Evaluate the inflammatory reaction alongside fungus-specific staining.

Anucleate stratum corneum

Viable epidermis

Dermis

Subcutaneous plane (context)

Schematic — not a clinical or histologic specimen

Slide 51 · PAS highlights fungal elements

Fungal cell-wall polysaccharides account for strong periodic acid–Schiff staining.

Bright pink to red fungal structures.

PAS visualizes fungal material and supports its identification in cornified tissue.

Anucleate stratum corneum

Viable epidermis

Dermis

Subcutaneous plane (context)

Schematic — not a clinical or histologic specimen

Slide 52 · PAS-positive hyphae within the cornified layer

Figure 25.39’s caption specifically describes red hyphae within the stratum corneum.

The relevant finding is both the staining reaction and its anatomic location.

The vector diagram is an original schematic, not the printed textbook photomicrograph.

Anucleate stratum corneum

Viable epidermis

Dermis

Subcutaneous plane (context)

Schematic — not a clinical or histologic specimen

Slide 53 · Read tissue location before inflammatory intensity

Observe where fungal structures are found within the keratinized compartment.

Then assess epidermal spongiosis and neutrophilic involvement.

Finally consider whether secondary bacterial infection contributes to the pattern.

Fungal location

Epidermal reaction

Superinfection context

Clinical → anatomic / tissue evidence → identification

Slide 54 · Diagnostic material can come from several sites

Scrapings from lesional cornified skin are appropriate specimens in the source account.

Involved hair or nail material can also contain fungi.

The specimen must correspond to the involved clinical structure.

SKIN

Stratum corneum

HAIR

Keratinized shaft

NAIL

Nail plate

Lesional sampling follows the affected keratinized structure

Slide 55 · Culture can identify the offending species

Culture of scraped material usually permits species identification.

The clinical syndrome itself principally identifies a site and recognizable phenotype.

Species attribution should not be inferred from a lesion schematic or PAS positivity alone.

Lesional scale / hair / nail

Culture: Species identification

Slide 56 · Diagnostic logic: Clinic to specimen to organism

Recognize an anatomic pattern and its key lesion morphology.

Sample the affected cornified skin, hair, or nail.

Use tissue observation or special staining to demonstrate fungi; Culture can establish species.

Clinical pattern

Correct specimen

Fungi / culture

Clinical → anatomic / tissue evidence → identification

Slide 57 · Nearby bacterial infection is a separate diagnosis

Impetigo is a superficial bacterial skin infection discussed adjacent to this section.

Its morphology emphasizes neutrophils and subcorneal pustules rather than PAS-highlighted hyphae.

Do not merge the neighboring impetigo passage into dermatophytosis histology.

Dermatophytosis

– Fungi in cornified skin

– PAS highlights hyphae

– Variable spongiosis/neutrophils

Impetigo

– Superficial bacterial infection

– Subcorneal neutrophilic pustule

– Crust and bacterial organisms

Slide 58 · Teaching case: A histology interpretation

A skin biopsy shows mild spongiosis and focal epidermal neutrophils.

PAS highlights red fungal hyphae in the anucleate surface keratin.

Which finding establishes superficial fungal localization, and which findings reflect host response?

HYPOTHETICAL TEACHING CASE

A skin biopsy shows mild spongiosis and focal epidermal neutrophils.

Discuss the question and justify the distinguishing features.

Slide 59 · Teaching case: Four distributions

Child with patchy scalp scale and hair loss; Adult with an inner-thigh moist red scaly patch.

Another patient has toe-web scaling; Another has clustered varied-color macules of the upper trunk.

Assign the correct source-described tinea label to each distribution.

HYPOTHETICAL TEACHING CASE

Child with patchy scalp scale and hair loss; Adult with an inner-thigh moist red scaly patch.

Discuss the question and justify the distinguishing features.

Slide 60 · Integrated clinical comparison

Entity

Where?

Most characteristic clue

Capitis

Scalp

Scale, crust, frequent hair loss

Barbae

Beard area

Adult male; uncommon

Corporis

Body skin

Expanding round plaque; scaly rim

Cruris

Groin / upper inner thigh

Moist red patch; scaly edge

Pedis

Feet / toe webs

Diffuse erythema and scale

Onychomycosis

Nails

Discolored, thickened, distorted plate

Versicolor

Upper trunk

Varied-color fine-scaled macules

Slide 61 · Integrated microscopic comparison

Question

Finding or source-based answer

Where is the fungus?

Anucleate cornified layer; hair or nails may also be involved

What may H&E show?

Mild spongiotic dermatitis and intraepidermal neutrophils

Why PAS?

Fungal walls stain bright pink to red

How identify species?

Culture of lesional material usually permits identification

Why can inflammation vary?

Organism, host response and bacterial superinfection

Slide 62 · High-yield diagnostic synthesis

Site establishes the tinea label; Lesion morphology refines clinical recognition.

Dermatophytes cause the principal site-defined syndromes; Malassezia furfur causes versicolor.

PAS-positive hyphae in surface keratin and culture address organism localization and identity.

Inflammation, particularly in pedis, may be modified by bacterial superinfection.

Site and phenotype

Examine involved keratin

Demonstrate fungal elements

Slide 63 · Primary source and visual integrity

Robbins, Cotran & Kumar: Pathologic Basis of Disease, 11th edition.

Clinical and histologic information is derived from the supplied skin-chapter section.

All scientific diagrams in this lecture are editable schematics, not observed specimens.