65.3 Chronic Eczema, Hidradenitis Suppurativa & Cutaneous Lupus

Chronic Eczematous Dermatoses: Phenotypic Distinctions & Management

Chronic eczema encompasses a spectrum of pruritic, inflammatory skin conditions sharing epidermal barrier dysfunction and immune hyperreactivity. While atopic dermatitis is the most prevalent pediatric form, four distinct chronic eczematous phenotypes frequently present in adult family medicine practice.

                    DIFFERENTIAL MATRIX: CHRONIC ECZEMATOUS DERMATOSES

   Disorder              Clinical Morphology & Distribution               Pathophysiology & Triggers        First-Line Evidence-Based Therapies
   ═══════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════
   Nummular Eczema       Sharply demarcated, coin-shaped ("nummular"),   Epidermal lipid depletion,         • Class 1–2 topical corticosteroids
   (Discoid Eczema)      intensely pruritic, 1–5 cm erythematous          xerosis, low humidity (winter      (Clobetasol 0.05% ointment)
                         scaly, crusted plaques; pretibial lower legs,    months), harsh alkaline soaps;    • Thick petrolatum-based emollients
                         dorsal hands, extensor upper extremities.        KOH NEGATIVE (rules out tinea!).   • "Soak and seal" bathing technique.
   ───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
   Dyshidrotic Eczema    Deep-seated, intensely pruritic, clear "tapioca  Contact allergy (nickel, cobalt), • Ultra-potent topical corticosteroids
   (Pompholyx)           pudding-like" microvesicles along lateral        excessive sweating (hyperhidrosis) (Clobetasol 0.05% under occlusion)
                         borders of fingers, palms, and soles; late-      frequent wet work, psychological  • Bland barrier repair ointments
                         stage desquamation and painful fissures.         stress; NOT a sweat gland disorder!• Cotton glove liners under work gloves.
   ───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
   Stasis Dermatitis     Golden-brown to brawny speckled pigmentation     Chronic venous insufficiency,     • Graduated compression therapy (20–30 mmHg;
                         (hemosiderin) over lower third of medial calf;   ambulatory venous hypertension,   MANDATORY ABI > 0.8 BEFORE WRAPPING!)
                         erythema, fine scaling, pruritus, pitting edema; extravasation of RBCs into dermis;• Leg elevation above heart levels
                         late "inverted champagne bottle" sclerosis.      prone to secondary contact allergy.• Mid-to-high potency topical steroids.
   ───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
   Lichen Simplex        Solitary, circumscribed, heavily thickened,      THE INTRACTABLE "ITCH-SCRATCH      • Super-potent topical steroids
   Chronicus             lichenified leathery plaque with accentuated     CYCLE"; repetitive mechanical      (Clobetasol ointment under occlusion)
   (Neurodermatitis)     skin markings and hyperpigmentation; posterior   rubbing and scratching of a focal  • Intralesional triamcinolone (5–10 mg/mL)
                         neck, ankles, wrists, anogenital region.         pruritic trigger; neuropathic base.• Habit reversal training; hydroxyzine.
   ═══════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════

Clinical Nuances of Adult Eczematous Variants

1. Nummular Eczema (Discoid Eczema):
   • Predominantly affects older adults during cold, dry winter months ("winter itch"). Transepidermal water loss drives profound microfissuring and secondary cutaneous inflammation.
   • The Tinea Corporis Trap: Nummular plaques are frequently misdiagnosed as tinea corporis ("ringworm") because of their circular shape. However, nummular plaques are uniformly scaly and vesicular across their entire surface, whereas tinea corporis exhibits an active, advancing scaly border with central clearing. A negative potassium hydroxide (KOH) preparation definitively rules out tinea.
   • Management: High-potency topical corticosteroids (clobetasol 0.05% or betamethasone dipropionate 0.05% ointment) applied BID for 2 to 4 weeks. Emollient hydration using the "soak and seal" technique: the patient bathes in lukewarm water for 15 minutes, pats dry without rubbing, and immediately coats damp skin with thick petrolatum within 3 minutes.
2. Dyshidrotic Eczema (Pompholyx):
   • Historical misnomer: it is not a disorder of sweat glands, though emotional stress and hyperhidrosis aggravate flares. Intensely pruritic vesicles reside deep within the thick stratum corneum of the palmar and plantar surfaces, giving the classic visual appearance of "tapioca pudding" embedded in the skin.
   • Chronic disease produces severe desquamation, painful bleeding fissures, and vulnerability to secondary bacterial infection (Staphylococcus aureus).
   • Management: Super-potent Class 1 topical corticosteroid ointments applied under occlusion (e.g., wearing white 100% cotton gloves overnight). Compresses with cold aluminum acetate (Burow's solution) for 15 minutes dry weeping acute vesicles.
3. Stasis Dermatitis & The Compression Mandate:
   • Driven by incompetence of the deep, superficial, or perforator venous valves in the lower extremities, causing sustained venous hypertension. Increased intravascular hydrostatic pressure forces erythrocytes through widened endothelial gaps into the interstitial dermis. Extravasated RBCs lyse, and macrophages break down hemoglobin into hemosiderin, generating the pathognomonic indelible reddish-brown or golden-brown pigmentation of the gaiter region.
   • Chronic untreated inflammation produces subcutaneous fat fibrosis: lipodermatosclerosis (woody induration tapering down the calf, producing an "inverted champagne bottle" or "bowling pin" deformity).

   • [!CRITICAL] Mandatory Pre-Compression Assessment: The Ankle-Brachial Index (ABI) Graduated compression therapy (20–30 mmHg or 30–40 mmHg stockings) is the undisputed cornerstone of stasis dermatitis management. However, compression is STRICTLY CONTRAINDICATED in the presence of severe peripheral artery disease. Physicians must check pedal pulses and calculate an Ankle-Brachial Index (ABI) before applying compression. If the ABI is $<0.5$ to $0.8$, compression can precipitate acute distal arterial ischemia and ischemic gangrene. Compression is completely safe only when $\text{ABI} \ge 0.8$.

   • Contact Sensitization Alert: The skin in stasis dermatitis exhibits an extraordinary rate of allergic contact sensitization. Topical neomycin, bacitracin, lanolin, and fragrance-containing lotions must be strictly avoided, as they trigger severe secondary contact dermatitis in >50% of patients.
4. Lichen Simplex Chronicus (Neurodermatitis):
   • Represents an end-stage reactive phenomenon: an intractable itch-scratch cycle. Repetitive mechanical rubbing and scratch trauma stimulate epidermal hyperplasia, hypergranulosis, and extensive orthohyperkeratosis, creating a raised, leathery, lichenified plaque with exaggerated skin markings.
   • The primary therapeutic objective is to physically break the itch-scratch cycle. Apply superpotent topical corticosteroids (clobetasol propionate 0.05% ointment) under an occlusive barrier (such as a hydrocolloid dressing or plastic wrap) that physically shields the skin from the patient's fingernails. For dense, recalcitrant plaques, intralesional triamcinolone acetonide (5 to 10 mg/mL) injected directly into the mid-dermis induces rapid flattening.

---

Hidradenitis Suppurativa (Acne Inversa): Staging & Escalation

Hidradenitis suppurativa (HS) is a chronic, recurrent, debilitating, destructive inflammatory disease of the terminal hair follicle in apocrine gland-bearing intertriginous anatomical zones. It carries an extraordinary psychological and physical burden, with profound pain, malodorous discharge, disfiguring contractures, and marked social isolation.

Pathophysiological Paradigm Shift

Historically mischaracterized as an infectious disorder of apocrine sweat glands, modern molecular dermatology has established that HS is primarily an auto-inflammatory disease of follicular occlusion:

1. Follicular Hyperkeratosis & Occlusion: Mechanical friction and nicotine-induced epidermal hyperkeratosis cause infundibular plugging of the terminal hair follicle in intertriginous skin.
2. Follicular Dilation & Rupture: Retained sebaceous and cellular contents cause massive follicular distension, culminating in rupture of the follicular basement membrane into the sterile deep dermis.
3. Massive Neutrophilic & Granulomatous Inflammation: Extruded keratin, bacteria, and lipid debris trigger Toll-like receptors, inflammasome activation (NLRP3), and an overwhelming release of pro-inflammatory cytokines: TNF-α, IL-1β, IL-17, and IL-12/23.
4. Sinus Tract (Tunnel) Formation & Fibrosis: Repetitive inflammation prompts epithelial cells to proliferate downwards, forming epithelialized dermal tunnels (sinus tracts) that connect deep abscesses. Healing leads to extensive fibrotic scarring, tissue destruction, and dense keloidal bridging.

Anatomic Distribution & High-Yield Hallmarks

• Sites: Axillae (most common), inguinal folds, perineum, perianal region, gluteal cleft, inframammary and intermammary creases, and inner thighs.
• The Double-Ended Open Comedone: Also termed the "tombstone comedone" or bridge comedone. Comedones featuring two or more distinct communicating follicular orifices separated by a bridge of normal skin. This is the pathognomonic clinical sign of hidradenitis suppurativa.
• Strong Clinical Associations:
  • Cigarette Smoking: Present in 80% to 90% of HS patients. Nicotine directly upregulates epidermal infundibular hyperkeratosis and fuels neutrophil chemotaxis. Smoking cessation is paramount.
  • Obesity & Metabolic Syndrome: Excess adipose tissue exacerbates mechanical shear forces, skin-on-skin friction, maceration, and chronic systemic hyperinsulinemia.
  • Depression & Suicide: HS carries the highest depression and suicide risk among all dermatologic conditions.

                  THE HURLEY STAGING SYSTEM & STEPWISE MANAGEMENT FOR HS

   Hurley Stage     Clinical Criteria                                 Evidence-Based Medical & Surgical Management
   ═══════════════════════════════════════════════════════════════════════════════════════════════════════════════════
   Stage I          Single or multiple isolated abscess formation;    • Topical Clindamycin 1% lotion/gel BID for 12 weeks
                    NO sinus tract (tunnel) formation;                • Oral Zinc Gluconate (90 mg daily) anti-inflammatory
                    NO cicatrization (scarring).                      • Antiseptic chlorhexidine 4% body washes
                                                                      • Intralesional triamcinolone (5–10 mg) for acute cysts.
   ───────────────────────────────────────────────────────────────────────────────────────────────────────────
   Stage II         Recurrent, widely separated abscesses with        • First-Line: Oral Doxycycline 100 mg BID for 10–12 weeks
                    evidence of sinus tract formation AND             • Second-Line: Oral Clindamycin 300 mg BID PLUS
                    cicatricial scarring; isolated tracts.               Oral Rifampin 300 mg BID combination for 10–12 weeks
                                                                      • Surgical de-roofing (unroofing) of isolated sinus tracts.
   ───────────────────────────────────────────────────────────────────────────────────────────────────────────
   Stage III        Diffuse or near-diffuse involvement across an     • TARGETED BIOLOGIC THERAPY:
                    entire anatomic region; multiple interconnected      - Adalimumab (Humira) high-dose FDA regimen
                    sinus tracts and coalescent abscesses with           - Secukinumab (Cosentyx) IL-17A inhibitor
                    extensive dense fibrotic scar networks.           • Wide radical surgical excision down to deep fascia.
   ═══════════════════════════════════════════════════════════════════════════════════════════════════════════════

Evidence-Based Escalation Protocol

• Hurley Stage I: Initiated with topical clindamycin 1% solution or gel applied BID for 12 weeks. Add daily chlorhexidine 4% or benzoyl peroxide washes to suppress bacterial colonization. For acute, severely inflamed, painful nodules, administer intralesional triamcinolone acetonide (5 to 10 mg/mL).
• Hurley Stage II: Initiate systemic therapy with oral doxycycline 100 mg BID for 10 to 12 weeks. The primary therapeutic mechanism of doxycycline in HS is non-antibiotic anti-inflammatory: it inhibits matrix metalloproteinases and neutrophil migration. If disease is refractory to doxycycline, escalate to combination therapy: oral clindamycin 300 mg BID PLUS oral rifampin 300 mg BID for 10 to 12 weeks.
• Hurley Stage III & Refractory Stage II: Targeted Biologics:
  • Adalimumab (Humira): The first FDA-approved biologic for moderate-to-severe HS. Requires a substantially higher dosage than rheumatoid arthritis: Loading dose of 160 mg subQ at Week 0, 80 mg at Week 2, then 40 mg weekly (or 80 mg every other week) maintenance.
  • Secukinumab (Cosentyx): Fully human anti-IL-17A monoclonal antibody, FDA-approved for moderate-to-severe HS. Dosed at 300 mg subQ weekly at Weeks 0, 1, 2, 3, and 4, followed by 300 mg every 4 weeks maintenance.

Surgical Interventions: Rules & Paradigms

• [!IMPORTANT] The Incision & Drainage (I&D) Fallacy Routine Incision and Drainage (I&D) of unruptured, inflammatory HS nodules should be avoided whenever possible. I&D does not address the underlying follicular pathology; it carries a recurrence rate approaching 100% within weeks, accelerates the development of chronic sinus tracts, and promotes severe fibrotic scarring. I&D should be reserved strictly as an emergency palliative measure to relieve agonizing fluid tension in large, fluctuant, pointing abscesses.

• Sinus Tract De-Roofing (Unroofing): A highly effective, tissue-sparing surgical technique performed under local anesthesia. The roof of the epithelialized sinus tract is blunt-dissected or excised using electrosurgery, the tract floor is scraped clean with a dermal curette, and the wound is left open to heal by secondary intention. Preserves surrounding healthy tissue with an exceptionally low localized recurrence rate (<10%).
• Wide Radical Surgical Excision: In advanced Hurley Stage III disease with diffuse coalescent tunnels, complete surgical resection of all hair-bearing skin and subcutaneous tissue down to the deep muscular fascia is required, followed by healing by secondary intention or split-thickness skin grafting.

---

Cutaneous Lupus Erythematosus (CLE): Subtypes, Diagnosis & Therapeutics

Cutaneous lupus erythematosus encompasses a spectrum of autoimmune dermatoses categorized into acute, subacute, and chronic subtypes based on clinical morphology, histopathology, serological profile, and risk of systemic lupus erythematosus (SLE).

                      CLASSIFICATION OF CUTANEOUS LUPUS ERYTHEMATOSUS

   Subtype                 Clinical Morphology & Distribution               Systemic SLE Risk & Autoantibodies    Prognosis & Scarring
   ═══════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════
   Acute Cutaneous Lupus   Malar / "Butterfly" rash: confluent erythema     > 90% associated with active SLE;     Non-scarring;
   Erythematosus (ACLE)    over nasal bridge and bilateral malar cheeks,    Flares mirror systemic lupus flares;  resolves without scarring;
                           CHARACTERISTICALLY SPARING NASOLABIAL FOLDS.     ANA, anti-dsDNA, anti-Smith, low C3/C4 post-inflammatory dyschromia.
   ───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
   Subacute Cutaneous      Non-scarring photosensitive eruption on sun-     ~50% meet criteria for mild SLE;      Non-scarring;
   Lupus (SCLE)            exposed upper back, chest, shoulders, extensor   STRONGLY ANTI-Ro/SSA POSITIVE (>80%); resolves with temporary
                           arms; annular/polycyclic OR papulosquamous.      High rate of DRUG-INDUCED SCLE!       vitiligo-like leukoderma.
   ───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
   Chronic Cutaneous Lupus Indurated, disk-shaped violaceous plaques        LOW RISK OF SYSTEMIC SLE (only 5–10%);PERMANENT ATROPHIC
   (Discoid Lupus / DLE)   with adherent follicular scale, carpet-tack sign;ANA negative or low in > 60%;         SCARRING; follicular
                           heals with central depigmentation and atrophy.   Localized to head, scalp, ears, face. destruction, ALOPECIA.
   ═══════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════

Clinical Nuances of Lupus Subtypes

1. Acute Cutaneous Lupus (ACLE):
   • The Classic Malar ("Butterfly") Rash: Symmetrical erythema and edema spanning the bridge of the nose and the malar convexities of both cheeks. The high-yield diagnostic hallmark is strict sparing of the nasolabial folds (the skin folds between the nose and lips), distinguishing ACLE from rosacea and seborrheic dermatitis, both of which prominently involve the nasolabial folds.
   • ACLE is a direct cutaneous marker of active systemic lupus erythematosus (>90% correlation); flares parallel systemic multi-organ disease (especially lupus nephritis).
2. Subacute Cutaneous Lupus (SCLE):
   • Presents as an intensely photosensitive, non-scarring eruption distributed across the sun-exposed upper torso ("V-neck" chest, upper back, shoulders, and extensor arms), typically sparing the central face.
   • Two clinical variants: 1) Annular/Polycyclic: ring-like erythematous plaques with central clearing and delicate peripheral scale; and 2) Papulosquamous/Psoriasiform: scaly red plaques that mimic psoriasis (distinguished by photodistribution and absence of thick silvery micaceous scale).
   • Serological Hallmark: Strongly associated with circulating anti-Ro/SSA antibodies (>80%) and anti-La/SSB antibodies.

   • [!IMPORTANT] Drug-Induced SCLE SCLE has the highest incidence of drug induction among all cutaneous lupus forms. Major offending pharmacological triggers include:

     • Antifungals: Terbinafine (most common!)
     • Cardiovascular: Hydrochlorothiazide, Calcium channel blockers (diltiazem)
     • Gastrointestinal: Proton pump inhibitors (omeprazole, pantoprazole)
     • Biologics: TNF-alpha inhibitors Drug-induced SCLE presents with anti-Ro/SSA antibodies and resolves completely within weeks to months following discontinuation of the culprit medication.

3. Discoid Lupus Erythematosus (DLE / CCLE):
   • The most common subtype of chronic cutaneous lupus. Manifests as discrete, indurated, coin-shaped (discoid) violaceous plaques with adherent hyperkeratotic scale.
   • The "Carpet-Tack" Sign (Cat's Tongue Sign): When the thick, adherent hyperkeratotic scale is mechanically peeled from an active discoid plaque, sharp, horn-like keratotic spicules are revealed on its undersurface, resembling carpet tacks. These spicules represent casts of keratin extending deep into dilated follicular infundibula.
   • Evolution & Cicatricial Alopecia: As active inflammation subsides, DLE plaques heal with permanent, irreversible central atrophy, porcelain-white depigmentation, telangiectasias, and hyperpigmented indurated borders. When DLE occurs on the scalp, it destroys hair follicle stem cells, resulting in permanent scarring (cicatricial) alopecia with complete loss of follicular ostia.

Diagnostic Evaluation: Biopsy & The Lupus Band Test

• Punch Biopsy: A 4-mm punch biopsy from the active, indurated inflammatory border of a lesion establishes the diagnosis:
  • Interface Dermatitis: Vacuolar degeneration and liquefaction of the basal cell layer with necrotic, apoptotic keratinocytes (Civatte bodies).
  • Dense superficial and deep perivascular and periadnexal lymphocytic infiltrate.
  • Thickening of the epidermal basement membrane zone and substantial dermal mucin deposition (revealed by Alcian blue staining).
• Direct Immunofluorescence (DIF / The Lupus Band Test):
  • In lesional skin, direct immunofluorescence reveals a continuous, bright, granular band of immunoglobulin G (IgG), IgM, and complement C3 deposited along the dermoepidermal junction.
  • High-Yield Concept: In pure discoid lupus, the Lupus Band Test is positive only in lesional skin. In systemic lupus erythematosus (SLE), the Lupus Band Test is frequently positive in both lesional and sun-protected, clinically normal, non-lesional skin.

Comprehensive Management of Cutaneous Lupus

1. Strict Broad-Spectrum Photoprotection: Ultraviolet radiation (UVA and UVB) triggers keratinocyte apoptosis, autoantigen translocation to the cell surface, and immune flare. Patients must practice rigorous photoprotection: daily application of broad-spectrum physical sunscreens (SPF ≥50 containing zinc oxide or titanium dioxide) reapplied every 2 hours, UV-protective clothing, wide-brimmed hats, and UV-filtering films on car and home windows.
2. Topical & Intralesional Therapies:
   • High-to-Superpotent Topical Corticosteroids: Clobetasol propionate 0.05% ointment is first-line for thick, hyperkeratotic discoid plaques on the scalp, ears, and trunk.
   • Topical Calcineurin Inhibitors: Tacrolimus 0.1% ointment or pimecrolimus 1% cream are preferred for facial lesions to prevent corticosteroid-induced skin atrophy, perioral dermatitis, and telangiectasias.
   • Intralesional Corticosteroids: Triamcinolone acetonide (5 to 10 mg/mL) injected directly into active, hyperkeratotic scalp or facial plaques halts scar progression.
3. First-Line Systemic Therapy: Hydroxychloroquine (HCQ):
   • Antimalarial agent; accumulates within intracellular lysosomes, raises pH, suppresses Toll-like receptor (TLR-7, TLR-9) signaling, and inhibits antigen presentation. Highly effective across all forms of CLE.
   • Dosing Rule: Administered at 200 to 400 mg orally daily. Maximum daily dose must not exceed 5.0 mg/kg of ACTUAL body weight per day (American Academy of Ophthalmology [AAO] safety guideline to prevent retinal toxicity; dosing based on ideal body weight overdoses thin individuals).
   • Therapeutic Latency: Hydroxychloroquine requires 8 to 12 weeks of continuous therapy to reach steady-state tissue levels and demonstrate clinical efficacy. Patients must be counseled not to discontinue the drug prematurely.
   • Mandatory Retinal Screening Protocol (AAO Guidelines):
     • Baseline Screen: Comprehensive dilated retinal examination within the first year of starting HCQ, including automated visual field testing (Humphrey Visual Field 10-2) and high-resolution Spectral-Domain Optical Coherence Tomography (SD-OCT).
     • Annual Screening: Initiated after 5 years of continuous therapy in patients without risk factors (or annually from baseline if high-risk: dose >5.0 mg/kg actual weight, renal impairment [eGFR <60 mL/min], concurrent tamoxifen use, or pre-existing macular disease).
     • Pathology: HCQ binds melanin within the retinal pigment epithelium. Unmonitored toxicity produces irreversible, blinding "bull's-eye" maculopathy (concentric ring of pigment atrophy surrounding the fovea). SD-OCT detects subclinical parafoveal photoreceptor thinning ("flying saucer sign") before irreversible visual field loss occurs.
   • The Smoking Interaction Pearl: Cigarette smoking dramatically reduces the therapeutic efficacy of hydroxychloroquine by accelerating hepatic drug metabolism and altering lysosomal trapping. Smoking cessation is essential for clinical response.