SKIN DISEASES AND CUTANEOUS LESIONS

Diagnosis, pathophysiology, treatment, and international therapeutic updates 2026

Comprehensive scientific and medical review updated 2026

Based on modern dermatology, immunology, infectious diseases, and evidence-based medicine

By DrRamonReyesMD ⚕️

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INTRODUCTION

The skin is the largest organ of the human body and represents an extraordinarily complex immunological, microbiological, neurological, and vascular interface.

Dermatological diseases carry far greater medical significance than is often perceived by the general population.

Many skin disorders reflect:

• systemic diseases,
• immunological disorders,
• infections,
• endocrine abnormalities,
• autoimmune diseases,
• genetic syndromes,
• drug toxicity,
• chronic systemic inflammation.

In addition, numerous dermatologic conditions produce:

• pain,
• severe pruritus,
• insomnia,
• anxiety,
• depression,
• social isolation,
• stigmatization,
• profound impairment in quality of life.

Modern dermatology now integrates:

• digital dermoscopy,
• histopathology,
• immunodermatology,
• molecular microbiology,
• diagnostic artificial intelligence,
• targeted biologic therapies,
• JAK inhibitors,
• advanced immunomodulation,
• regenerative skin medicine.

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1. ACNE

DEFINITION

Acne vulgaris is a chronic inflammatory disease of the pilosebaceous unit.

PATHOPHYSIOLOGY

Four major mechanisms are involved:

• follicular hyperkeratinization,
• sebaceous hypersecretion,
• proliferation of Cutibacterium acnes,
• inflammatory immune activation.

TYPICAL LESIONS

• open and closed comedones,
• papules,
• pustules,
• nodules,
• cysts,
• atrophic scars.

DIAGNOSIS

Primarily clinical.

Differential diagnosis includes:

• rosacea,
• folliculitis,
• perioral dermatitis,
• drug-induced acne,
• hidradenitis suppurativa.

TREATMENT 2026

Mild acne

• topical retinoids,
• benzoyl peroxide,
• combined topical clindamycin therapy.

Moderate acne

• doxycycline,
• lymecycline,
• hormonal therapy in selected women.

Severe acne

• oral isotretinoin.

Isotretinoin remains the most effective treatment for severe nodulocystic acne.

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2. PSORIASIS

DEFINITION

A chronic immune-mediated inflammatory dermatosis.

PATHOPHYSIOLOGY

Central involvement of:

• IL-17,
• IL-23,
• TNF-α,
• Th17 activation.

CLINICAL FORMS

• plaque psoriasis,
• guttate psoriasis,
• pustular psoriasis,
• erythrodermic psoriasis,
• nail psoriasis,
• psoriatic arthritis.

DIAGNOSIS

Clinical examination plus dermoscopy.

Biopsy in uncertain cases.

TREATMENT 2026

Mild disease

• topical corticosteroids,
• calcipotriol,
• keratolytics.

Moderate-to-severe disease

Modern biologics:

• secukinumab,
• ixekizumab,
• guselkumab,
• risankizumab,
• deucravacitinib.

IL-23 inhibitors currently show outstanding long-term efficacy.

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3. ECZEMA / DERMATITIS

DEFINITION

A heterogeneous group of inflammatory skin diseases.

SYMPTOMS

• pruritus,
• xerosis,
• erythema,
• lichenification.

MAIN TYPES

• atopic dermatitis,
• contact dermatitis,
• irritant dermatitis.

DIAGNOSIS

• clinical history,
• patch testing,
• differential exclusion.

TREATMENT 2026

• intensive emollients,
• topical corticosteroids,
• calcineurin inhibitors,
• dupilumab,
• JAK inhibitors.

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4. VITILIGO

DEFINITION

An autoimmune depigmenting disorder.

MECHANISM

Immune-mediated destruction of melanocytes.

DIAGNOSIS

• Wood’s lamp examination,
• dermoscopy,
• autoimmune screening.

TREATMENT 2026

• topical corticosteroids,
• tacrolimus,
• NB-UVB phototherapy,
• topical ruxolitinib.

JAK inhibitors represent one of the most important recent advances.

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5. TINEA / DERMATOPHYTOSIS

CAUSATIVE ORGANISMS

• Trichophyton,
• Microsporum,
• Epidermophyton.

PRESENTATION

• annular lesions,
• active scaly border,
• pruritus,
• centrifugal expansion.

DIAGNOSIS

• KOH preparation,
• fungal culture,
• dermoscopy.

TREATMENT

Localized disease

• topical terbinafine,
• clotrimazole.

Extensive disease

• oral terbinafine,
• itraconazole.

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6. ROSACEA

DEFINITION

A chronic centrofacial inflammatory dermatosis.

SUBTYPES

• erythematotelangiectatic,
• papulopustular,
• phymatous,
• ocular.

TRIGGERS

• alcohol,
• heat,
• ultraviolet radiation,
• stress,
• spicy foods.

TREATMENT 2026

• topical ivermectin,
• azelaic acid,
• subantimicrobial doxycycline,
• vascular laser therapy,
• low-dose isotretinoin in selected cases.

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7. URTICARIA

DEFINITION

Mast-cell-mediated wheal formation.

CLASSIFICATION

• acute,
• chronic spontaneous,
• inducible.

DIAGNOSIS

Primarily clinical.

TREATMENT 2026

First-line therapy

• second-generation H1 antihistamines.

Refractory disease

• omalizumab,
• cyclosporine in selected cases.

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8. WARTS (HPV)

CAUSATIVE AGENT

Human Papillomavirus (HPV).

TYPES

• common warts,
• plantar warts,
• flat warts,
• periungual warts.

TREATMENT

• salicylic acid,
• cryotherapy,
• electrocautery,
• intralesional immunotherapy.

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9. MELASMA

DEFINITION

Acquired facial hypermelanosis.

ASSOCIATED FACTORS

• ultraviolet radiation,
• hormones,
• genetics,
• inflammation.

TREATMENT 2026

• strict photoprotection,
• hydroquinone,
• tranexamic acid,
• chemical peels,
• selective fractional laser therapy.

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10. IMPETIGO

ETIOLOGY

• Staphylococcus aureus,
• Streptococcus pyogenes.

FORMS

• bullous,
• nonbullous.

TREATMENT

Localized disease

• mupirocin.

Extensive disease

• cephalexin,
• dicloxacillin.

Community-acquired MRSA must always be considered.

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11. SEBORRHEIC DERMATITIS

ASSOCIATIONS

• sebaceous activity,
• inflammatory response,
• Malassezia yeasts.

TREATMENT

• ketoconazole,
• ciclopirox,
• mild corticosteroids,
• calcineurin inhibitors.

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12. HERPES ZOSTER

CAUSATIVE AGENT

Varicella-Zoster Virus (VZV).

CLINICAL FEATURES

• neuropathic pain,
• dermatomal vesicular eruption,
• unilateral distribution.

COMPLICATIONS

• postherpetic neuralgia,
• ocular involvement,
• encephalitis.

TREATMENT

• valacyclovir,
• acyclovir,
• multimodal analgesia.

PREVENTION

Recombinant Shingrix® vaccine.

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CRITICAL DIFFERENTIAL DIAGNOSIS

Many dermatologic lesions resemble one another.

Potentially dangerous diagnostic confusions include:

• melanoma vs benign nevus,
• lupus vs rosacea,
• psoriasis vs eczema,
• tinea vs dermatitis,
• cellulitis vs inflammatory dermatitis,
• herpes zoster vs herpes simplex.

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DERMATOLOGIC RED FLAGS 🚨

Urgent medical evaluation is required if there is:

• fever,
• necrosis,
• extensive blistering,
• disproportionate pain,
• purpura,
• mucosal involvement,
• respiratory distress,
• rapid progression,
• immunosuppression,
• evolving pigmented lesions.

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FINAL CONCEPT — DRRAMONREYESMD ⚕️

Modern dermatology has evolved from simple visual observation into a highly sophisticated specialty integrating:

• immunology,
• microbiology,
• genetics,
• molecular pharmacology,
• oncology,
• diagnostic artificial intelligence,
• advanced biologic therapies.

The skin not only reflects cutaneous disease; it frequently serves as a diagnostic window into complex systemic disorders.

Accurate dermatologic diagnosis requires:

• precise semiology,
• clinical correlation,
• visual expertise,
• dermoscopy,
• histopathology,
• advanced differential reasoning.

Because in medicine:

visually similar lesions may represent completely different diseases in severity, pathophysiology, prognosis, and treatment.

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INTERNATIONAL SCIENTIFIC REFERENCES AND SOURCES

• American Academy of Dermatology (AAD)
• British Association of Dermatologists (BAD)
• National Institute for Health and Care Excellence (NICE) Dermatology Guidelines
• World Health Organization (WHO) Skin NTDs and Dermatology Resources
• Centers for Disease Control and Prevention (CDC) Dermatology and Infectious Skin Diseases
• DermNet NZ
• New England Journal of Medicine (NEJM) Dermatology Reviews
• Journal of the American Academy of Dermatology (JAAD)
• The Lancet Dermatology Resources

By DrRamonReyesMD ⚕️ | Updated 2026