- Clinical science
Collection of dermatological disorders
Sebaceous and epidermoid cysts
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Terminology
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Epidermoid cyst
- Most common cutaneous cyst
- Lined by stratified squamous epithelium and contains keratin
- Sebaceous cyst: cyst formed by blockage of sebaceous gland; contains sebum
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Epidermoid cyst
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Clinical findings
- Slow growth, mobile, firm, painless nodule
- Dark colored punctum; may be seen on a sebaceous cyst
- Localized predominantly on the face, head, neck, back, or genital area
- Infection; possible (→ painful, erythematous mass that may exude pus)
- High probability of recurrence
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Treatment
- Asymptomatic cysts do not need treatment
- Intralesional steroids (triamcinolone) may help reduce inflammation
- In case of infection or pressure symptoms; → total surgical excision
- Oral antibiotics for infected cysts
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Variant: trichilemmal cyst (pilar cyst)
- Definition: cyst that forms around a hair follicle
- Clinical findings
- Similar to sebaceous cysts; but without a central excretory duct to the epidermis
- Content is hard, firm, and odorless
- Treatment: total excision
References:[1][2][3][4]
Cat scratch disease
- Definition: benign, self-limiting infectious disease that is transmitted mainly by cats (scratching, biting, or licking)
- Pathogen: Bartonella henselae (gram-negative bacillus, aerobic)
- Epidemiology: predominantly affects young adults and children
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Clinical features
- General: malaise, loss of appetite, fever
- Localized
- One or more 5–10 mm large, erythematous, non-tender cutaneous papules or vesicles develop approx. 4–6 days after exposure (in > 50% of cases)
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Swollen, tender lymphadenopathy 1–3 weeks following exposure
- Develops as primary lesions disappear
- Usually unilateral, occasionally suppurative
- Most commonly involves lymph nodes of axillae, neck, or groin
- Resolves after 2–4 months
- In immunocompromised individuals
- Bacillary angiomatosis
- Hepatic peliosis
- Bacteremia and endocarditis
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Diagnosis
- Bacterial culture from blood, swabs, or lymph node aspirate
- Antibody testing
- Histological study:
- Warthin-Starry staining; of involved lymph node may demonstrate clusters of bacilli.
- H&E staining of cutaneous lesions may demonstrate granulomas.
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Treatment
- Usually not needed
- Azithromycin is indicated for severe, persistent, or debilitating disease
References:[5][6][7][8]
Cutaneous mastocytosis (urticaria pigmentosa)
- Definition: a myeloproliferative condition, characterized by mast cell proliferation and accumulation in the skin; affects mainly children
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Clinical findings
- Varied clinical and morphological appearance
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Maculopapular cutaneous mastocytosis (formerly urticaria pigmentosa)
- Brown-red macules or plaques on the head and lateral face
- Pruritic lesions, often associated with systemic symptoms like rhinorrhea, wheezing, and headache
- Lesions are rich in mast cells.
- Diagnosis: Darier sign → characteristic intense redness following mechanical irritation of the lesions; potentially urticarial swelling, pruritus, or blistering
- Treatment: PUVA therapy, antihistamines, mast-cell stabilizer (cromolyn), glucocorticoids
Miliaria
- Definition: transient, papular exanthem following exposure to heat
- Etiology: blockage of the eccrine sweat ducts in hot and/or humid environments
- Localization: : mainly the trunk, neck, and intertriginous areas
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Therapy
- General measures to reduce sweating: wear light, breathable fabrics, remove occlusive bandages etc.
- Topical steroids; (hydrocortisone, triamcinolone), topical antibiotics for pustular eruptions (clindamycin, erythromycin)
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Miliaria crystallina | Miliaria rubra | Miliaria profunda | |
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Level of sweat duct blockage |
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References:[9]
Nummular eczema (nummular dermatitis)
- Definition: chronic, inflammatory skin condition; that is characterized by well-demarcated round lesions
- Etiology: : multifactorial; primarily an immunological hypersensitivity reaction; (dermatitis) due to xerosis and damage to the epidermal lipid barrier
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Clinical findings
- 2–5 cm large, coin-shaped, well-demarcated erythematous plaques
- Pruritus, scabs
- Affects primarily the extremities
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Therapy
- Symptomatic
- Skin hydration with wet wraps and lotions
- Oral antihistamines
- Topical steroids and immune modulators; (tacrolimus and pimecrolimus) to decrease inflammation
- Symptomatic
References:[10][11]
Gianotti-Crosti syndrome
- Definition: maculopapular exanthem; association with viral infections, especially hepatitis B and Epstein-Barr Virus (EBV)
- Epidemiology: peak incidence in children up to 6 years of age
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Clinical findings
- Affects the face, buttocks, and extensor surfaces of the extremities affected
- Possibly pruritus
- Self-limiting, ranging between 10 days and 6 months duration
- Treatment: symptomatic
Angiokeratoma
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Definition: benign ectasia of the upper dermal vessels with hyperkeratotic involvement of the papillary dermis
- Angiokeratoma circumscriptum: verrucous, bluish-black plaques located primarily on the extremities
- Treatment: laser ablation, mainly a cosmetic procedure
Dyshidrotic eczema
- Definition: multiple, severely itchy, tight clusters of blisters on the palms and soles, which contain a clear fluid
- Etiology: unknown, believed to be multifactorial ; in rare cases, a manifestation of allergic contact dermatitis or atopic dermatitis
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Treatment
- Topic or oral corticosteroids
- PUVA or UVA treatment
Erythema ab igne
- Translation: “redness from fire”
- Definition: reticular erythema with teleangiectasias
- Etiology: chronic heat application (infrared radiation, hot water bottles)
- Course: with continued heat exposure → marbled, brownish hyperpigmentation caused by increased melanin production
Callus/Clavus
- Callus: thick, toughened skin caused by mechanical pressure
- Clavus: painful, hyperkeratotic lesion with a center core (“corn”) caused by frictional forces and trauma
Pitted keratolysis (keratoma plantare sulcatum)
- Definition: pit-like corneal defects on the soles of the feet with a severe burning sensation
- Epidemiology: particularly affects the feet of the individuals working in a hot, humid environment (for e.g., athletes, laborers, and soldiers posted in tropical climates)
- Etiology: caused by maceration and various bacteria; most often occurs when footwear is not sufficiently breathable
Localized lipodistrophy
- Definition: localized degeneration of subcutaneous adipose tissue
- Etiology: following subcutaneous injections, secondary to certain drugs , pressure-induced, or idiopathic
Perioral dermatitis (stewardess disease)
- Definition: chronic facial dermatitis affecting the perioral region
- Epidemiology: primarily women aged 20–30 years of age, and children
- Etiology: unknown; presumably caused by regular application of (glucocorticoid) creams and cosmetics
- Clinical findings
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Treatment
- Avoidance of cosmetics, drugs containing corticoids
- If necessary, local or systemic tetracycline
SAPHO syndrome
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Definition and clinical findings: rheumatological, spondylarthritic disease with simultaneous occurrence of
- Synovitis
- Acne
- Pustulosis (palmoplantar)
- Hyperostosis (particularly of the sternoclavicular joint, spine, or the pelvis)
- Osteitis (chronic recurrence)
- Etiology: unknown
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Diagnosis
- Mainly a clinical diagnosis
- If necessary, X‑ray imaging , scintigraphy , and MRI
- Treatment: primarily symptomatic
Livedo reticularis
Definition: A vascular syndrome that may be caused either by benign autonomic dysregulation of cutaneous perfusion or pathological obstruction of blood vessels.
Benign livedo
- Pathophysiology: autonomic dysregulation; (functional disturbance) causing slowed cutaneous perfusion in response to external factors (e.g., cold)
- Epidemiology: higher incidence in young women
- Clinical findings
- Symmetrical; livedo reticularis (regular, small, round) on the extremities and sometimes trunk
- Triggered by the cold and regresses after application of warmth
- Treatment: warmth, alternately cold and warm baths, sauna
- Prognosis: improves with age
Pathological livedo
- Pathophysiology: localized obstructions slow the blood flow (organic disturbance)
- Etiology: vascular diseases (cholesterol embolism, atherosclerosis, vasculitis)
- Clinical findings
- Irregular; , unusual livedo reticularis of the extremities and sometimes trunk
- Persists after warming the skin
- Treatment: treat the underlying disease
Livedo reticularis that does not regress after application of warmth is indicative of an underlying vascular disease and requires treatment!
References:[12]
Xeroderma pigmentosum
- Definition: : rare, autosomal-recessive hereditary skin disease caused by defective DNA repair mechanisms → minimal UV radiation can lead to severe skin damage, and has carcinogenic effects
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Clinical findings
- Extreme sensitivity to light with pigmentary changes
- Development of multiple precancerous lesions; (actinic keratoses) and eventually malignant skin cancer; (basal cell carcinoma, spinocellular carcinoma, melanoma) already in early childhood
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Management:
- Complete protection from light and avoidance of sun exposure
- Frequent skin cancer screening, retinoids as prophylaxis
- Prognosis: severely limited life expectancy
References:[13]
Pseudofolliculitis barbae
- Epidemiology: most common in black males (hair shafts with a tendency to form tight coils)
- Pathophysiology:
- Clinical findings: firm, hyperpigmented, tender, pruritic papules and pustules on hair-growing areas (beard)
- Diagnosis: clinical appearance; culture is usually negative
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Treatment
- Cessation of shaving; alternative hair removal techniques (e.g., laser hair removal)
- Adjunctive: topical treatments (e.g., retinoids, corticosteroids, antimicrobials)
Albinism
- Definition: : Congenital disorders of melanin synthesis resulting in hypopigmentation.
- Epidemiology
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Classification
- Ocular albinism (OA): only the visual system (e.g., eyes, optic nerve) is affected.
- Oculocutaneous albinism (OCA): absence of melanin in the skin, hair, and the visual system (e.g., eyes, optic nerve).
- May be associated with Chédiak–Higashi syndrome
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Pathophysiology: impaired melanin production
- Due to dysfunctional tyrosinase activity, or impaired transport of tyrosine or melanin.
- Normal melanocyte number, decreased or absent melanin production.
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Clinical features
- Eyes
- Translucent, hypopigmented, blue, grey, or green irides ,
- Photophobia, decreased visual acuity
- Strabismus, nystagmus, amblyopia
- Abnormalities of the optic nerve
- Skin and hair: milky, white color, photosensitivity, sunburns.
- Associated with increased risk of skin cancer
- Eyes
- Treatment: only supportive treatment, no curative treatment available.