6.5 Sebaceous & Sudoriferous Gland Disorders

6.5 Sebaceous & Sudoriferous Gland Disorders

1. Sebaceous Gland Disorders & Acne Pathology

Disorders of the sebaceous glands stem from abnormal sebum production, follicular hyperkeratinization, and bacterial colonization within the pilosebaceous canal.

                                  ┌──────────────────────────────────────────────────────────┐
                                  │             PATHOPHYSIOLOGY OF ACNE VULGARIS             │
                                  └────────────────────────────┬─────────────────────────────┘
                                                               │
                ┌──────────────────────────────┼──────────────────────────────┬──────────────────────────────┐
                ▼                              ▼                              ▼                              ▼
 ┌──────────────────────────────┐ ┌──────────────────────────────┐ ┌──────────────────────────────┐ ┌──────────────────────────────┐
 │ 1. RETENTION HYPERKERATOSIS  │ │ 2. ANDROGEN SEBUM SURGE      │ │ 3. C. ACNES PROLIFERATION    │ │ 4. INFLAMMATION & RUPTURE    │
 ├──────────────────────────────┤ ├──────────────────────────────┤ ├──────────────────────────────┤ ├──────────────────────────────┤
 │ • Defective desquamation     │ │ • Androgens (DHT/testost.)   │ │ • Anaerobic bacterium feeds  │ │ • Bacterial lipases digest   │
 │ • Keratinocytes fail to shed │ │ • Sebaceous gland hypertrophy│ │   on sebum triglycerides     │   sebum into irritant FFAs     │
 │ • Form cohesive cellular plug│ │ • Excessive lipid flow       │ │ • Proliferates in blocked,   │ │ • Follicular wall ruptures   │
 │   in follicular infundibulum │ │ • Provides bacterial food    │ │   oxygen-deprived follicle   │ │ • Neutrophils swarm -> pus   │
 └──────────────────────────────┘ └──────────────────────────────┘ └──────────────────────────────┘ └──────────────────────────────┘

Pathophysiology of Acne Vulgaris

Acne vulgaris is a chronic inflammatory disorder of the pilosebaceous unit governed by four interconnected pathogenic steps:

1. Retention Hyperkeratosis: The hereditary tendency of follicular keratinocytes to stick together and fail to shed normally (defective desquamation), accumulating within the infundibulum to create a microscopic plug (microcomedone).
2. Sebaceous Gland Hyperactivity: Circulating androgens (such as dihydrotestosterone / DHT) stimulate sebaceous glands to enlarge and produce excessive amounts of sebum.
3. Bacterial Proliferation (Cutibacterium acnes): Cutibacterium acnes (formerly Propionibacterium acnes), an anaerobic, Gram-positive bacterium residing naturally inside follicles, proliferates rapidly in the sebum-rich, oxygen-depleted environment.
4. Inflammatory Cascade & Follicular Rupture: C. acnes produces lipases that hydrolyze sebum triglycerides into free fatty acids (FFAs), provoking an intense immune response. Leukocytes infiltrate, the follicular wall ruptures into the surrounding dermis, and inflammatory papules, pustules, nodules, or cysts form.

The Four Clinical Grades of Acne Vulgaris

   GRADE I (Mild)              GRADE II (Moderate)          GRADE III (Mod-Severe)        GRADE IV (Severe / Cystic)
   ┌──────────────────────┐    ┌──────────────────────┐    ┌──────────────────────┐    ┌──────────────────────┐
   │ • Open comedones     │    │ • Many open/closed   │    │ • Numerous papules   │    │ • Widespread cysts   │
   │ • Closed comedones   │    │   comedones          │    │ • Numerous pustules  │    │ • Deep nodules       │
   │ • <10 papules        │    │ • 10-25 papules      │    │ • Severe erythema    │    │ • Interconnected sinus│
   │ • No scarring        │    │ • Mild inflammation  │    │ • High scarring risk │    │ • Medical Referral   │
   └──────────────────────┘    └──────────────────────┘    └──────────────────────┘    └──────────────────────┘

Comedones, Milia & Sebaceous Retention Disorders

• Open Comedone (Blackhead): A non-inflammatory, open follicular impaction of sebum and cornified keratinocytes. The characteristic black color is caused by the oxidation of melanin and lipids upon direct exposure to ambient oxygen, NOT dirt or poor hygiene.
• Closed Comedone (Whitehead): A non-inflammatory impaction where the follicular opening remains covered by an intact layer of stratum corneum. Because sebum and keratin cannot oxidize, the lesion presents as a small, smooth, pale or flesh-colored bump.
• Milia: Small (1–2 mm), firm, pearl-like epidermal keratin cysts containing compacted dead skin cells with no visible follicular pore opening. Commonly found around the delicate periorbital eye area and upper cheeks; require gentle lancing with a sterile lancet (where state scope permits) or professional keratolytic exfoliation.
• Seborrhea: An abnormal condition of severe oiliness and overproduction of sebum by the sebaceous glands, resulting in a greasy facial sheen and predisposed to seborrheic dermatitis.
• Asteatosis: A deficiency of sebum production, producing chronically dry, rough, scaly skin with a compromised lipid barrier. It is the physiological opposite of seborrhea and is common in mature clients, in low-humidity environments, and after over-cleansing with alkaline products. Distinguish it carefully from dehydration: asteatosis is a shortage of oil and calls for lipid replacement with emollients and occlusives, while dehydration is a shortage of water and calls for humectants. A client can present with both simultaneously.
• Steatoma (Wen / Sebaceous Cyst): A subcutaneous, encapsulated tumor of the sebaceous gland filled with sebum and epithelial debris, ranging in size from a pea to an orange, commonly found on the scalp, neck, or back. Must be excised surgically by a physician.

2. Sudoriferous (Sweat) Gland Disorders

Sudoriferous disorders involve abnormalities in thermal regulation, perspiration volume, or bacterial interaction with sweat.

Exam Memory Anchors — Lesion & Disorder Key Facts:

• Primary Lesion Size Thresholds: Macule = <1 cm (Flat); Papule = <1 cm (Solid); Nodule = >1 cm (Deep Solid); Vesicle = <1 cm (Fluid); Bulla = >1 cm (Fluid).
• Blackhead Color Cause: Melanin and sebum oxidation upon contact with air, NOT dirt.
• Keloid Definition: Scar tissue growing beyond the boundaries of the original wound (prevalent in Fitzpatrick IV–VI).
• Acne Referral Mandate: Grade IV acne (cystic/nodular) mandates immediate dermatologist referral.