Cutaneous Skin Infections: Short Notes

A clinical photograph displaying bullous impetigo on an extremity. The image shows the characteristic progression following the rupture of flaccid bullae. Key features include multiple superficial erosions with raw, erythematous bases, surrounded by prominent peripheral collarettes of scale representing the remnants of the blister roof. A thin, light brown (varnish-like) crust is visible in several areas, distinct from the thicker, honey-colored crust associated with non-bullous impetigo. The lesions are confluent in some regions, demonstrating the highly contagious spread of the infection within the superficial epidermis. This visual representation is an educational example of bacterial skin infection caused by Staphylococcus aureus, highlighting the diagnostic features of post-bullous erosion and scaling suitable for medical training in dermatology and pediatrics.

This is a high-resolution clinical photograph of a localized facial lesion on the left cheek/perioral region. Imaging modality: standard dermatology photography; viewpoint: anterior-lateral view. The lesion shows a red, erythematous plaque with a centered yellow crust, suggestive of a crusted exudate over an eroded surface. The surrounding skin is mildly inflamed with intermittent scaling. The crust appears honey-colored and adherent, characteristic of impetigo, a contagious superficial bacterial infection commonly caused by Staphylococcus aureus or Streptococcus pyogenes. Differential diagnoses include nonbullous impetigo vs bullous impetigo, bacterial folliculitis, contact dermatitis with secondary crusting, or eczema with secondary infection. No evident vesicles beyond the crust; no facial vesicular eruption is visible. If infection is present, treatment typically involves topical antibiotics (mupirocin, fusidic acid) or systemically if extensive, with emphasis on hygiene to prevent spread. The image emphasizes early recognition of impetiginous lesions on the face in adults and children. Clinically correlated signs such as fever, regional lymphadenopathy, or spreading redness would guide management. For radiographic correlation, consider bacterial culture in persistent cases or when confirming etiology. This photograph educates dermatology students on morphological features of crusted erythematous plaques. Note lesion color, crust density, and surrounding edema for assessment.

Clinical dermatology photograph illustrating multiple circular or oval plaques on pink, near-normal skin, each with a prominent golden-yellow crust consistent with impetigo. The image is a macroscopic skin photograph captured under diffuse ambient lighting with non-magnified view of the trunk or proximal limb region. Visual features include centrally eroded areas surrounded by a thick crust that appears amber to brown, with mild surrounding erythema and slight scaling. Lesions are clustered in a roughly linear or patchy distribution, lacking deep ulceration or purulent discharge. This presentation is typical of nonbullous impetigo, a superficial bacterial infection most often caused by Staphylococcus aureus or Streptococcus pyogenes; however, crusts may also form in secondary bacterial colonization of dermatitis. The image emphasizes a crusted, honey-colored exudate over nearly intact epidermis, consistent with surface infection, minimal necrosis, and a superficial dermal inflammatory response. Clinically, impetigo is highly contagious, commonly affects children, and may accompany mild pruritus. Differential diagnoses include crusted eczema, tinea corporis with secondary bacterial infection, and dermatitis herpetiformis in other contexts. Recognizing the yellow crust and peripheral erythema supports prompt initiation of topical antiseptics or antibiotics, and assessment for regional lymphadenopathy or systemic signs if dissemination occurs. This image is useful for educational comparison, dermatology atlases, and clinical training in infectious skin diseases.

This clinical photograph demonstrates a localized lower extremity ulceration, specifically located on the anterior surface of the right leg distal to the knee. The primary lesion is a circular, punched-out ulcer with a deep red, granulated base and raised, hyperpigmented, indurated borders suggestive of localized inflammation or necrosis. The surrounding perilesional skin displays brownish-yellow hyperpigmentation and xerosis. An inset image provides a close-up of the dorsal aspect of the foot and ankle, highlighting diffuse edema, generalized skin darkening, and shiny, tense skin texture. These findings are clinically significant for chronic venous insufficiency, diabetic foot complications, or infectious processes like cutaneous leishmaniasis or ecthyma. The visual material is useful for dermatology and primary care education regarding the assessment of chronic lower limb ulcers, peripheral edema, and associated stasis-related skin changes.

Clinical photograph of two distinct, rapidly progressive skin ulcers on a patient's lower extremity. The lesion on the left is a well-circumscribed, roughly circular ulcer featuring a central area of dark necrotic eschar and peripheral purpuric discoloration. Yellowish fibrinous exudate is visible within the wound bed. The lesion on the right demonstrates a deeper, punched-out ulcerative morphology with irregular, ragged borders and an erythematous, edematous rim. Its base contains raw red granulation tissue, areas of necrosis, and visible serosanguinous fluid streaking inferiorly. Both lesions are approximately 3 to 4 cm in diameter and exhibit signs of severe tissue breakdown and localized inflammation. This visual presentation is characteristic of necrotizing soft tissue infections or aggressive ulcerative conditions such as ecthyma gangrenosum, requiring urgent diagnostic evaluation for underlying pathogens or systemic involvement.

This clinical photograph set displays dermatological manifestations of cutaneous diphtheria (Corynebacterium diphtheriae). Image A shows a close-up of a patient's lower extremity featuring two small, circular ulcerated lesions. The lesions appear well-demarcated with an erythematous, inflammatory border and a central fibrinous exudate. A medical measuring tape is placed alongside the lesions to provide clinical scale, indicating the ulcers are approximately 1 to 1.5 cm in diameter. Image B provides a high-detail view of a characteristic diphtheritic ulcer. This lesion demonstrates a classic 'punched-out' morphology, consisting of a thick, greyish-white necrotic pseudomembrane centrally, which has a slightly textured or leathery appearance. The central necrotic core is surrounded by a prominent, bright red ring of inflamed tissue. These images illustrate the non-specific but clinically significant presentation of cutaneous diphtheria, which often involves multiple inflammatory ulcers that may mimic impetigo or tropical ecthyma, particularly in endemic regions such as French Guiana.

This dermatology clinical photograph documents a solitary boil (furuncle) on the cutaneous surface. Modality: Clinical photography; technique: macro close-up imaging of the skin with standard, noninvasive illumination. The lesion is a dome-shaped, erythematous nodule with a central yellowish-white pustular core representing purulent material within a hair follicle. Surrounding skin shows mild edema and perifollicular erythema. The lesion appears tender on palpation; no drainage is evident although the pus core is visible. The image captures typical signs of acute bacterial folliculitis progressing to furunculosis, most commonly caused by Staphylococcus aureus, with neutrophil-rich inflammatory infiltrate and abscess formation around the follicular unit. Clinically, this finding supports a diagnosis of furuncle rather than a simple acne lesion or epidermal cyst; differential diagnoses include carbuncle, abscess, or inflamed epidermoid cyst. Pathophysiology involves follicular occlusion, microbial colonization, and localized pus accumulation. Management implications include warm compresses, incision and drainage if fluctuance is present, and targeted antibiotics for extensive infection or cellulitis or systemic signs. This image is educational for medical trainees in recognizing cutaneous infections, dermatology case discussions, and demonstrations of localized skin abscesses and follicular infection. Useful for exam prep, clinical decision making, and patient education about boil treatment and outcomes globally.

Imaging modality: Clinical photography of a cutaneous lesion. Anatomical location: left forearm skin, superficial dermis and hair follicle involvement. Perspective: close-up, frontal view of a solitary boil. Visual features: round, dome-shaped erythematous plaque with a central pustule and a creamy-white fluctuant core; surrounding perilesional induration; mild surrounding erythema; skin folds visible; no surrounding necrosis. Pathology inference: consistent with furuncle (boil) caused by Staphylococcus aureus infection of a hair follicle with inflammatory abscess formation within the dermis and subcutaneous tissue. In the clinical context, this lesion may arise in patients receiving Bruton tyrosine kinase inhibitors, which can disrupt B-cell function and predispose to bacterial skin infections; however, localization remains cutaneous and localized drainage is often therapeutic. Diagnostic significance: highlights a localized cutaneous infection; differential includes folliculitis, carbuncle, impetigo, abscess; MRSA risk; culture may guide antibiotics. Clinical correlation: correlate with systemic signs (fever, leukocytosis); assess need for wound drainage; versus incision and drainage; consider antibiotic therapy targeting Staphylococcus aureus; review BTK inhibitor therapy with treating oncologist for infection risk mitigation. Potential applications: educational dermatology cases, infection management training, BTK inhibitor adverse effect surveillance, antimicrobial stewardship. Image-guided documentation supports clinical decision-making, antibiotic stewardship, and comparative learning for dermatology and infectious disease education and training.

This is a clinical close-up photograph of a single left axillary skin lesion consistent with a boil (furuncle) or localized abscess. Modality: clinical photography; technique: macro close-up with standard color-calibrated lighting; scale is provided by a ruler for size estimation (~1.5–2 cm in diameter). The lesion is erythematous and tender with a raised, dome-shaped nodular configuration in the subcutaneous tissue of the axillary hair-bearing region. Surrounding perilesional erythema and mild edema reflect an acute inflammatory process. A central pus collection may be present; in some furuncles the area can be fluctuant, though drainage is not visible in this still image. The differential includes furuncle/abscess, folliculitis, hidradenitis suppurativa, and infected sebaceous cyst; HS typically shows recurrent painful nodules and sinus tracts in the axilla. Clinically, such lesions arise from bacterial infection of hair follicles, most often Staphylococcus aureus, with perifollicular inflammation. The image provides educational documentation for clinical scenarios, tele-dermatology triage, and surgical planning regarding drainage and antibiotic therapy. It supports visual recognition, teaching for medical students and residents, and correlation with histopathology or dermoscopy when available. Documentation of size, location, and morphology supports monitoring, patient education, and outcome assessment after drainage, incision, or antibiotic therapy, and aids research in cutaneous infectious disease.

A composite of nine clinical photographs (labeled a-i) illustrating various clinical manifestations of dermatophyte infections (tinea) across different anatomical sites. (a) Tinea capitis on the scalp showing inflammatory patches and alopecia. (b) Tinea faciei presenting as an erythematous, scaly plaque on the cheek and ear. (c) Tinea corporis on the arm displaying an annular morphology with scaly borders. (d) Close-up of tinea corporis (ringworm) emphasizing the characteristic raised, erythematous leading edge and central clearing. (e) Tinea imbricata/corporis on the torso featuring concentric rings. (f) Tinea cruris (jock itch) showing confluent erythematous patches in the inguinal region. (g) Interdigital tinea pedis exhibiting maceration and scaling in the toe webbing. (h) Chronic 'moccasin-type' tinea pedis characterized by diffuse hyperkeratotic scaling on the plantar surface. (i) Onychomycosis presenting as distal subungual thickening, yellowish discoloration, and nail plate dystrophy. The collection serves as an educational reference for dermatological diagnosis based on lesion morphology and distribution.

Clinical photograph of a skin lesion on the left shoulder/upper chest region displaying an annular, erythematous plaque with central clearing and fine desquamation. The lesion shows a pink-red, slightly raised border and irregular, patchy hypopigmentation in the center. Surrounding skin is mildly erythematous, with peripheral scale and no obvious vesiculation. The pattern resembles a ring-shaped dermatitis consistent with tinea corporis (dermatophyte infection) or an annular plaque with an active border. Differential diagnoses include tinea corporis, granuloma annulare, discoid eczema, plaque psoriasis with annular configuration, and contact dermatitis. The lesion appears well-demarcated with expansion margins and central clearing; the border may be scaly and demonstrates variable pigmentation. Notable features: peripheral pruritic erythema, annular geometry, scaly edge, central clearing, and mild crusting. Clinical significance: ring-like lesions on trunk or proximal limbs warrant superficial fungal evaluation (KOH preparation) and fungal culture, particularly in individuals without immunosuppression. Management implications include topical antifungals (terbinafine, azoles) and escalation to systemic therapy if widespread or unresponsive. This image is suitable for dermatology education, teledermatology triage, and differential diagnostic training focusing on annular erythematous plaques. Keywords for indexing: annular lesion, dermatophyte infection, ringworm, border scaling, central clearing, papulosquamous, inflammatory dermatology, infection vs. inflammation, imaging modality: clinical photo reference.

Clinical photography of a single well-circumscribed, erythematous, scaly plaque on the ventral/lateral forearm. The lesion exhibits classic annular configuration with peripheral scaling and a relatively clear central area, consistent with a ring-shaped dermatologic eruption. The observed lesion diameter is approximately 1–2 cm; the erythema is mild-to-moderate, and the scale appears fine, desquamative at the active border. This presentation is most suggestive of a superficial dermatophyte infection, i.e., tinea corporis (ringworm), though annular variants of eczema or psoriasis can mimic this pattern. The image demonstrates a well-demarcated border, thin rim of scale, and central clearing, with no overt vesiculation or ulceration. In a clinical context, one would consider mycological confirmation via potassium hydroxide (KOH) preparation and fungal culture, Wood’s lamp examination, and response to topical antifungal therapy as diagnostic adjuncts. Differential diagnoses include tinea corporis, annular psoriasis, nummular eczema, granuloma annulare, and pityriasis versicolor; however, the morphology here—scaly, active edge with central clearing—favors dermatophyte infection. This photograph is useful for dermatology education, teledermatology triage, pattern-recognition training, and patient counseling about fungal skin infections, contagiousness, and treatment expectations. Clinicians may correlate with pruritus, lesion distribution, exposure history, and lesion evolution over time.

Imaging modality: clinical photography of a single toe. Location: dorsal aspect of the middle toe nails (onychomycosis). Visual features: chalky, opaque white patches on the dorsal nail plate with slight surface roughness; nails appear thickened at the distal edge; surrounding nail folds are unremarkable; no subungual hyperkeratosis is clearly visible in this image, though that feature can accompany fungal nail disease. Pathology: features compatible with superficial white onychomycosis caused by dermatophyte invasion of the dorsal surface of the nail plate. Diagnostic significance: the appearance supports a fungal nail infection; confirmation with potassium hydroxide (KOH) preparation or culture may be pursued if needed. Differential considerations include Candida nail infection, distal lateral subungual onychomycosis, trauma-induced leukonychia, or psoriasis of the nail, which may mimic the white patches but have distinct patterns. Clinical use cases: dermatology and primary care screening for nail fungus, monitoring antifungal therapy response, educational examples of nail plate disorders, and telemedicine assessment of distal digits. Terminology: onychomycosis, tinea unguium, superficial white onychomycosis, toe nail infection. The image is useful for teaching nail anatomy, differential diagnosis of white nail plate changes, and patient counseling on treatment expectations.

Clinical photography of the right hallux nail demonstrating total nail involvement (total onychomycosis) with marked subungual hyperkeratosis. The nail plate is thickened and opaque, with yellowish-brown crumbly debris filling the subungual space and lifting of the proximal edge. The proximal nail fold remains intact but overlies a markedly dystrophic nail bed. The surface of the nail shows irregular flaking and lamellar cracking consistent with chronic dermatophytic infection; the subungual keratotic mass is prominent. Imaging modality: Clinical photography; close-up, macro view; noninvasive. The anatomical location is the toenail unit, hallux, digit 1 of the foot. The observed features correspond to mycotic nail disease (onychomycosis) with hyperkeratosis, hypertrophy (onychosis), and subungual debris. Differential diagnosis includes psoriasis nail dystrophy, lichen planus, trauma-related nail dystrophy, and non-dermatophyte mold onychomycosis; however, the total involvement and characteristic subungual keratosis favor onychomycosis. Clinically, this finding is associated with prolonged fungal infection, potential discomfort, infection risk, and functional impairment; it may respond to systemic or topical antifungal therapy and debridement. This image is relevant for dermatology education, clinical diagnosis practice, and image-based medical training; useful for AI datasets focusing on nail pathology, fungal infections, and subungual hyperkeratosis. This image aids lesion recognition, grading severity, and treatment planning decisions.

Clinical photography of a dystrophic toenail. Modality: high-resolution close-up digital photograph of the great toe nails in dorsal orientation. Location: toenail unit, plantar/dorsal aspect, with visible nail plate and distal edge. The image demonstrates thickened, yellow-brown discolored nail plate with a rough, crumbly surface and subungual keratinous debris. A crescent-shaped band of discoloration along the inner edge of the distal nail bed is evident, consistent with onychomycosis. Mild onycholysis at the distal margin may be present. Periungual skin appears uninflamed without surrounding erythema. Observed pattern suggests Ungual candidiasis? No; treat as dermatophyte infection. Overall features are typical of tinea unguium (onychomycosis) with nail plate dystrophy and subungual hyperkeratosis. Clinically significant as fungal nail infection that can cause nail thickening, discomfort, and cosmetic concern. Diagnostic significance: supports clinical suspicion of onychomycosis; differential includes nail psoriasis, lichen planus, trauma. Diagnostic workflow would include KOH prep, fungal culture, or PCR to confirm dermatophyte infection. Potential clinical uses include education, tele-dermatology triage, and guiding antifungal therapy decisions (systemic vs topical) with follow-up assessment. This image is suitable for teaching nail anatomy, pathology, and infection patterns in dermatology. Its simplicity aids rapid recognition in primary care and remote consultations.

This diagnostic image is a high-magnification dermoscopy of the scalp, illustrating classic features of inflammatory tinea capitis (kerion). The clinical findings include prominent, ill-defined patches of erythema and thick, yellowish-white diffuse scaling (scales) across the scalp surface. Notable trichoscopic markers of fungal infection are present, specifically 'comma hairs'—short, fractured hair shafts that exhibit a distinctive curved, comma-like morphology (indicated by black arrows). Additionally, the field shows several dystrophic broken hairs and the presence of white hair casts (perifollicular keratin cylinders) encircling proximal hair shafts. These features are highly suggestive of ectothrix fungal invasion and are utilized in clinical dermatology to differentiate tinea capitis from other forms of alopecia or inflammatory scalp conditions. The image demonstrates key diagnostic indicators for medical students and clinicians specializing in dermatology and infectious diseases.

Clinical and diagnostic images illustrating tinea capitis progressing to kerion, caused by Microsporum canis. Panel A displays a clinical photograph of the scalp featuring a well-circumscribed, solitary inflammatory mass. The lesion is characterized by significant alopecia, erythema, an eroded surface, and yellowish crusting, consistent with a kerion. Panels B and C demonstrate Wood’s lamp examinations of the same area. Panel B shows a characteristic bright, intense blue-greenish fluorescence across the entire lesion, a pathognomonic finding for certain ectothrix fungal infections like M. canis. Panel C displays the same lesion after two weeks of fluconazole treatment, showing a significant reduction in fluorescence intensity and area, indicating therapeutic response and a decrease in fungal load. This sequence is used for medical education to demonstrate clinical diagnosis, diagnostic imaging using ultraviolet light (Wood’s lamp), and the objective monitoring of treatment efficacy in inflammatory fungal infections of the scalp.

Clinical photography of a scalp lesion consistent with kerion, an inflammatory tinea capitis. Modality: dermatologic photography, close-up, frontal view of the left eyebrow/scalp region. The lesion is a raised, erythematous plaque with conspicuous yellow-brown crusts and surrounding scaling. Central areas show pustules and crusting with focal necrosis potential, and there is hair breakage and non-scarring alopecia at the periphery. The lesion is bilaterally inflamed but focal, with edema of the surrounding dermis producing a boggy, indurated impression. The pattern is unilateral and localized to the frontal-temporal scalp and periorbital area, compatible with fungal infection rather than primarily bacterial. The appearance corresponds to kerion: thick, crusted plaque, painful nodularity, regional lymphadenopathy not visible in image. Dermatoscopic details not applicable; histology would show perifollicular granulomatous inflammation with fungal elements. Clinically, kerion signals active dermatophytosis requiring systemic antifungal therapy and possibly adjunctive topical antifungals, with careful differential from bacterial cellulitis and folliculitis. Early recognition is critical to prevent scarring alopecia. This image, used for medical education, illustrates characteristic features: inflammatory plaque, yellow crusts, scaling perifollicular involvement, and localized hair loss, aiding differential diagnosis, treatment planning, and patient counseling. Note: fungal etiology confirmed by culture or molecular methods guides therapy selection and prognosis monitoring.

Comprehensive description: This is a high-resolution clinical photograph of the trunk depicting pityriasis versicolor–related hypopigmented patches. Imaging modality: Clinical photography of the anterior torso using standard lighting, color calibration, and digital capture to document surface pigmentary changes. Anatomical localization: Trunk (anterior chest and upper abdomen) within the integumentary system, illustrating cutaneous involvement of the thoracic skin. Visual features: irregular, coalescent hypopigmented macules and patches with fine superficial scale; color contrast against surrounding darker skin; scalloped margins with some central clearing and patchy confluent areas; distribution is predominantly on the chest, extending laterally and toward the upper abdomen. Pathology/disease: Classic presentation of pityriasis versicolor from Malassezia species causing superficial pigmentary disturbance without deep tissue invasion. Diagnostic significance: Supports clinical diagnosis of tinea versicolor; findings are often complemented by Wood’s lamp fluorescence (copper-orange) and potassium hydroxide examination revealing yeast and hyphae; antifungal therapy yields pigment restoration. Clinical use cases: Dermatology education, documentation of pigmentary disorders, monitoring response to topical or systemic therapy, and research into Malassezia-related hypopigmentation. This description emphasizes terminology such as pityriasis versicolor, tinea versicolor, hypopigmented macules, trunk, anterior view, Malassezia pigmentary change, and antifungal management. The image serves as a teaching and archival reference for pigmentary dermatoses in clinics.

Clinical photograph of in vivo human forearm skin showing hypopigmented, confluent patches compatible with pityriasis versicolor (tinea versicolor). The image demonstrates localized involvement of the volar forearm with pale, irregularly shaped macules that coalesce into larger hypopigmented patches. The lesions display subtle surface scaling and well-defined but variable borders; surrounding skin is darker, giving a contrast typical for this condition. The distribution is on sun-exposed or humid skin regions and may appear more prominent after tanning. Pathophysiology involves superficial Malassezia yeast colonization of the stratum corneum with production of acids that disrupt melanin synthesis, leading to pigmentary heterogeneity. Clinically, pityriasis versicolor presents as nonpruritic hypo- or hyperpigmented patches that fluoresce under Wood's lamp. Differential diagnoses include vitiligo, postinflammatory hypopigmentation, and pityriasis alba; however, tinea versicolor generally preserves skin texture and shows minimal scale on closer inspection. Diagnostic confirmation is often via KOH preparation revealing the spaghetti-and-meatballs pattern of yeast and hyphae. Management is antifungal (topical azoles, selenium sulfide, or oral therapy for extensive disease). This image is valuable for dermatology education, pigmentary disorder assessment, and search-indexing for clinical skin disease repositories, aiding learners in recognition and differential diagnosis of superficial fungal hypopigmentation.

The image depicts a clinical photograph of axillary and proximal chest skin showing pigmented follicular lesions consistent with pityriasis versicolor. Imaging modality is clinical photography using a standard digital color camera to document cutaneous involvement. Visual features include multiple small brown, slightly scaly papules and patches centered on hair follicles, with fine surface scaling and patchy distribution. Lesions appear hypo- or hyperpigmented relative to adjacent skin, with preserved contour and no overt inflammation. The follicular localization suggests involvement of the follicular ostia and sebaceous-rich zones of the upper trunk. Histopathology (if sampled) would typically reveal Malassezia yeast and hyphae within the stratum corneum; KOH preparation may demonstrate the classic spaghetti-and-meatballs pattern. Clinically, pityriasis versicolor is a superficial fungal infection that can mimic other pigmentary disorders such as seborrheic dermatitis or vitiligo; differential diagnoses include post-inflammatory hyperpigmentation and tinea corporis. This image is valuable for dermatology education, telemedicine, and patient counseling, and supports planning of antifungal therapy (azoles, selenium sulfide) with attention to recurrence in hot, humid environments. For educational indexing, include commonly used synonyms such as tinea versicolor, Malassezia infection, pityriasis versicolor; this enhances recognition in dermatology databases, textbooks, and image banks used by clinicians, students, and researchers.

Histopathology of a common cutaneous wart (verruca vulgaris) on a routine hematoxylin and eosin stained skin biopsy. Imaging modality: Light microscopy of a skin biopsy with standard H&E staining. The epidermis shows marked hyperplasia with broad acanthosis and pronounced papillomatosis, producing a corrugated, exophytic surface. Hyperkeratosis with focal parakeratosis is evident at the tips of the projections. Rete ridges extend downward in elongated, serpiginous fashion. Filiform or finger-like papillary extensions project into the dermis with narrow dermal cores. Infected keratinocytes exhibit koilocytosis: enlarged, pale nuclei with perinuclear halos, a hallmark of HPV-related cytopathic effect. The underlying dermis shows mild chronic inflammation without deep invasion. Together, these features define verruca vulgaris and help distinguish it from verruca plana and other papillary lesions. Diagnostic significance: HPV-induced epidermal hyperplasia with papillomatosis and koilocytosis is characteristic; supports clinical diagnosis of a common wart. Differential considerations include verruca plana, seborrheic keratosis, keratoacanthoma, and cutaneous horn. Clinical correlation: rough, hyperkeratotic papules on exposed or frequently traumatized skin, commonly on hands and fingers; treatment options include cryotherapy, salicylic acid preparations, immunotherapy, and recurrence risk is moderate. Correlation with clinical morphology strengthens diagnostic confidence and guides targeted destructive therapies.

Histology of a common cutaneous wart (Verruca vulgaris) presenting in a hematoxylin and eosin stained slide viewed under light microscopy at high magnification. The specimen originates from skin biopsy with epidermal and superficial dermal involvement. The epidermis shows marked acanthosis with pronounced papillomatosis and irregular thickening of rete ridges. The upper epidermal layers contain numerous koilocytes—keratinocytes with enlarged, raisinoid nuclei surrounded by clear halos—and there is conspicuous cytoplasmic clearing and perinuclear halos. Basophilic keratohyalin granules are abundant in the granular layer, giving the granular layer a dark basophilic appearance. Hyperkeratosis and focal parakeratosis are evident in the stratum corneum, with mild epidermal spongiosis and dermal inflammatory infiltrate composed of lymphocytes and rare neutrophils. The dermal-epidermal junction is not disrupted, consistent with benign HPV-induced hyperproliferation. These features collectively support verruca vulgaris: HPV infection of keratinocytes leading to hyperplasia, koilocytosis, and a papillary surface. Clinically, verruca vulgaris is contagious, often skin-to-skin transmitted, frequently arising in children and young adults, and commonly treated with cryotherapy, salicylic acid, or immunomodulators. Differential diagnoses include seborrheic keratosis and squamous cell carcinoma; however, absence of atypia and invasion supports benign wart. The histopathology correlates with clinical management decisions and prognosis.

Histopathology of a cutaneous verruca vulgaris (common wart) demonstrated on a hematoxylin and eosin stained skin biopsy. The specimen shows an exophytic, cauliflower-like lesion arising from the epidermis with marked epidermal hyperplasia. Papillomatosis is evident as elongation and upgrowth of the rete ridges with surface projections. Acanthosis is present with diffuse thickening of the squamous cell layer; hyperkeratosis with parakeratosis is observed at the lesion surface, reflecting aberrant keratinization. Filiform papillae extend from the surface and end in finger-like projections. The dermal interface is relatively thin with a sparse inflammatory infiltrate and preserved dermal connective tissue. There is no obvious dysplasia or invasion. The histologic pattern is characteristic for HPV-induced verruca vulgaris, though koilocytosis (perinuclear halos in squamous cells) may be variably present and not always conspicuous in all sections. This morphology supports diagnosis of a benign, HPV-associated cutaneous wart rather than a corn, seborrheic keratosis, or other hyperkeratotic lesion. Clinically, verruca vulgaris presents as discrete, rough, hyperkeratotic papules or plaques on exposed or non-exposed skin, commonly in children and young adults. The diagnostic significance lies in recognizing papillomatosis with acanthosis and parakeratosis as classic features, guiding management such as topical therapies, cryotherapy, or surgical removal and reducing misdiagnosis with keratotic lesions.