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MindMap Gallery Dermatology and Venereology 004 Biogenic Skin Diseases Section 3
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Dermatology and Venereology 004 Biogenic Skin Diseases Section 3
004 Biogenic Skin Diseases Section 3: Biogenic Skin Diseases Mind Map, which summarizes viral skin diseases, animal skin diseases - scabies, etc.
Edited at 2024-03-25 18:59:36
Dermatology and Venereology 004 Biogenic Skin Diseases Section 3
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Chapter 4 Biogenic Dermatoses
Section 3 Viral Skin Diseases
1. Herpes simplex
[Cause] HSV: Type Ⅰ (HSV-1) is mainly an infection of the head and face, type Ⅱ (HSV-2) is mainly an infection of parts below the waist (such as external genitalia); after primary infection, the virus lurks in the sensory ganglia. During recurrent infection, the virus replicates and migrates along nerve fibers to the skin and mucous membranes; hematogenous spread of the virus may occur in newborns and those with low immunity.
[Clinical manifestations]
First hair
It can be a subclinical infection (90%); mild infection has no obvious clinical discomfort, and the basic damage is clusters of small blisters, obvious local edema, often accompanied by varying degrees of pain and superficial lymph node enlargement.
organ damage
∎ Herpes gingivostomatitis: relatively common, mostly caused by HSV-1, most common in children aged 1 to 5 years old; characterized by blisters on the lips/buccal mucosa/palate, swelling, bleeding, erosion, and yellow gums membrane; the patient has salivation, bad breath, and pain when eating; accompanied by fever, malaise, and local lymph node enlargement; the natural course of the disease is 1 to 2 weeks
Neonatal herpes simplex: mostly caused by HSV-2 and infected through the birth canal; onset 5 to 7 days after birth, manifested by blisters and erosion on the skin/oral mucosa/conjunctiva, and in severe cases, systemic symptoms; divided into skin-eye-oral localization type, central nervous system type, disseminated type
Herpetic keratoconjunctivitis: more serious; manifests as potential corneal ulcer, accompanied by eyelid herpes, preauricular lymph node swelling and pain; in severe cases, corneal perforation may occur, leading to blindness
Herpetic eczema (eczema herpeticum)/Kaposi varicelliform eruption: refers to infection with HSV-1 or HSV-2 on the basis of original skin diseases (mostly infantile eczema, atopic dermatitis) A skin disease; manifested by sudden clusters of blisters on the original skin lesions, which quickly turn into pustules, with an umbilical depression at the top and red surrounding areas.
Fainting; the scabs dry and fall off after 1 to 2 weeks, leaving some superficial scars and pigmentation; may be accompanied by systemic symptoms such as high fever and local lymph node enlargement; most prognosis is good
Incubation herpes: The skin lesions are limited to the contact area and appear as clusters of blisters
Herpetic whitlow: occurs on the fingers and manifests as deep, painful blisters
Herpes gladiatorum: occurs in wrestlers and manifests as blisters caused by skin contact infection
Genital herpes: see later
Recurrent type
30 to 50% of oral herpes relapse, while genital herpes relapses frequently.
There may be local itching/burning sensation in the lesion 1 to 2 hours before recurrence, followed by erythema, clustered papules and blisters (smaller), which may merge with each other; after a few days, the blisters will rupture, form erosion, and scab and heal; systemic symptoms are mild, Course of disease 1~2w
[Examination] Detection of viral antibodies can assist diagnosis; virus culture and identification is the gold standard for diagnosis
[Treatment] Principles: shorten the course of the disease, prevent secondary bacterial infection and systemic dissemination, and reduce the chance of recurrence and spread.
Systemic drugs
Initial onset: Acyclovir
Recurrent type: Use intermittent therapy, preferably within 24 hours of the onset of prodromal symptoms or skin lesions. Frequent relapsing type: Use continuous suppressive therapy.
Severe symptoms of primary infection/extensive skin lesions: Acyclovir 5~10 mg/kg, intravenously administered once every 8 hours
Acyclovir-resistant patients: intravenous foscarnet
topical medications
Astringent, dry, prevent secondary infection
2. Herpes zoster
[Cause and pathogenesis]
1. Varicella-zoster virus (VZV): a human herpes virus; only one serotype; humans are the only host and source of infection, and are transmitted through direct contact and air
2. Pathogenesis: After invading the human body, it has skin- and nerve-friendly properties, forms eosinophilic inclusions in the nuclei of infected cells, and fuses with neighboring cells to form multinucleated giant cells; the first infection often causes chickenpox (a few are latent infections), The virus can then lie dormant in neurons; when certain stimuli cause the body's immunity to decline, the virus can become active again, causing inflammation and necrosis of latent ganglia (neuralgia), and then spread to the skin (herpes zoster)
3. After recovering from the disease, you can gain longer-lasting immunity and generally will not relapse.
(1) Chickenpox
[Clinical manifestations]
Basic performance
The incubation period is generally 14 to 17 days; systemic symptoms may occur; the rash is centripetally distributed, starting as pinpoint-sized macules/papules, gradually turning into mung bean-sized blisters, oval in shape, with an umbilical depression in the center, and surrounding redness; 2 to 4 days The rash occurs in batches one after another, and erythema, papules, blisters and scabs can be seen at the same time ("four generations under one roof"); no scars are left after healing, and the course of the disease is about 2 weeks.
special type
Bullous chickenpox: It is more common in children <2 years old and manifests as bullae of 2 to 7 cm that quickly turn into erosion without leaving scars.
Hemorrhagic chickenpox: more common in patients with malnutrition and immunosuppressive treatment
Neonatal chickenpox: rare, usually transmitted from mother during delivery
Chickenpox in adults: It is more obvious than chickenpox in children, and the rash is more severe. It is often accompanied by fever and obvious itching.
complication
Varicella pneumonia, varicella encephalitis, Reye syndrome, thrombocytopenic purpura, secondary infection, erythema multiforme
(2) Herpes zoster
[Clinical manifestations] There is no seasonality, it is sporadic, and it is more common in adults (the incidence rate increases with age)
Typical performance
Prodromal symptoms: Low-grade fever, fatigue, and local lymph node swelling and pain in the first few days of onset; the affected area may show hypersensitivity/pain.
Skin lesions
Local skin flushing, followed by the appearance of clusters of unfused miliary to soybean-sized papules/papuloherpes, which quickly turned into watery
Blisters, the blister fluid is clear, the blister wall is tense and shiny, and there is redness around it; the rash comes out one after another and is distributed along the nerves in a band-like manner, and the skin between the rashes is normal; the course of the disease is generally 2 to 3 weeks (3 to 4 weeks for the elderly), and after a few days The blisters dry up and scab, leaving temporary light red spots/pigmentation.
Skin lesions mostly occur on one side of the body, arranged along a certain peripheral nerve distribution area, generally not exceeding the midline; the most common location is the thoracic segment (intercostal nerve), followed by the lumbar segment, cervical segment, and trigeminal nerve (the ophthalmic branch is common) )
The manifestations of skin lesions are diverse and are related to the patient's resistance; they can be manifested as abortive type (only neuralgia without skin lesions), incomplete type (only erythema and papules without blisters, which then subside), and bullous type. , hemorrhagic type, gangrenous type, generalized type (the virus spreads through the blood, producing widespread chickenpox-like rash, involving more than 2 ganglia at the same time, producing skin lesions in multiple areas on the contralateral/ipsilateral side)
accompanying symptoms
Neuralgia—zoster-associated pain (ZAP): Herpes zoster can be accompanied by neuralgia before, during, and after the skin lesions heal, which is paroxysmal and burning. /Knife-like pain; after the skin lesions subside
When neuralgia persists (usually after 4 weeks), it is called postherpetic neuralgia (PHN).
Local lymph node swelling and pain
Involvement of anterior horn motor neurons: muscle weakness, skin paralysis of corresponding parts
special type
trigeminal herpes zoster
Ophthalmic branch - Herpes zoster ophthalmicus: more common in the elderly, with severe symptoms and severe pain. It can be combined with angular and conjunctivitis, and even cause blindness.
Maxillary branch: blisters may appear in the uvula and tonsil areas
Mandibular branch: blisters may appear on the front of the tongue and buccal mucosa
Herpes zoster oticus: The virus invades the facial nerve and auditory nerve; manifests as ear canal/tympanic membrane herpes; Ramsay-Hunt syndrome (facial paralysis and earache) may occur when the geniculate ganglion is involved and the motor and sensory fibers of the facial nerve are also affected. External auditory canal herpes)
Disseminated herpes zoster: refers to the appearance of more than 20 skin lesions outside the affected dermatomes. It is mainly seen in people with severely low body resistance.
Complicated by HIV infection: The condition is severe or manifests as deep impetigo-like skin lesions, which can easily cause eye and nervous system complications and may recur.
[Treatment] Self-limiting
systemic treatment
Antiviral: early stage (starting 48 to 72 hours after the onset of rash), sufficient dose; oral or intravenous administration of acyclovir
Pain relief: Acute pain→TCAs; Subacute/chronic pain→Gabapentin/pregabalin/NSAIDs
Glucocorticoids: It is believed that early and reasonable application can inhibit the inflammatory process and shorten the course of ZAP in the acute phase, but it has no definite preventive effect on PHN; it is mainly used to improve immunity in elderly patients without contraindications within 7 days of the disease: transfer factor, thymosin
topical treatment
External use: unbroken blisters → calamine lotion, acyclovir cream; blisters broken → 3% boric acid solution, 0.5% neomycin ointment; if combined with eye damage, please consult an ophthalmologist
Physiotherapy: such as spectrum, audio, ultraviolet, helium-neon laser
3. Warts (verrucae, wart)
[Definition] It is a group of benign growths caused by HPV infection of the skin and mucous membranes, including common warts, flat warts, plantar warts, and genital warts (see below)
[Cause] HPV: Humans are the only host and are transmitted through direct/indirect contact; type 1 is related to plantar warts, types 2, 4, and 28 are related to common warts, types 3, 10, 28, and 41 are related to flat warts, and type 65 and Related to pigmented flat warts, types 6, 11, 12, 16, 18, 32, and 42 are related to genital warts
[Pathology] Cells in the upper part of the granular layer and spinous layer are vacuolated (hollow cells); virus particles in the nucleus are seen under the electron microscope
[Clinical manifestations]
1. Verruca vulgaris/"thousand-day sore"/"wart"
Basic performance
It usually occurs on the dorsum of the hands and feet and around the nails. It has a long course but can subside naturally. It initially appears as a papule the size of a pin, and then gradually enlarges to a hemispheric shape the size of a mung bean. The surface is rough and becomes keratinized spines, which are hard and gray-brown in texture. There are no symptoms, but there may be pain when the wart is squeezed from both sides to the center.
special type
Periungual wart: occurs in the periungual area. Subungual wart: occurs in the nail bed.
Filiform warts: single soft filamentous protrusions, height <1cm, with dry keratinization at the top; common on the neck, forehead, and eyelids. Filiform warts: clusters of multiple finger-like protrusions on the same soft base. Apical keratosis; common on scalp and between toes
2. Plantar warts (verruca plantaris): They are common warts that occur on the soles of the feet. They are most common at pressure points on the feet (such as the middle of the metatarsal bones). Trauma, friction, and excessive foot sweating are the triggers. They appear as yellowish-brown warts parallel to the skin. Thickened horny plaques with a rough surface and clear boundaries, surrounded by a slightly elevated horny ring; when the surface is peeled off with a fingernail, a soft core of horny material tightly clustered into filaments can be found underneath; it can be seen after trimming with a knife Bleeding from the top becomes small black dots after solidification; when it contains multiple keratin soft cores, it is called a mosaic wart; it may be painful or asymptomatic.
3. Flat warts (verruca plana): They commonly occur on the face/back of hands/forearms of children and adolescents; they appear as flat papules ranging from the size of a pinhead to a mung bean, with a smooth, hard surface and normal skin color/light brown; they are multiple and scattered/densely distributed. , typical papules arranged in strips along the scratches (i.e., Koebner phenomenon) can be found; generally there are no subjective symptoms or occasional slight itching; the course of the disease is long and can subside on its own (the spontaneous subsidence rate is the highest among all clinical HPV infections), A few may relapse
4. Genital warts/genital warts: see below
[Differential diagnosis] Plantar warts VS corns VS calluses
【treat】
topical medications
Suitable for those with large skin lesions or those who are not suitable for physical therapy; commonly used drugs such as 0.05~0.1% retinoic acid ointment (flat warts), 5-fluorouracil ointment (retaining pigmentation → use with caution on the face), 3% phthalamide cream, Pingyangmycin (refractory common warts/plantar warts), 5% imiquimod ointment (flat warts/common warts)
Physiotherapy
Suitable for those with small number of skin lesions; such as freezing, electrocautery, curettage, laser
Systemic drugs
Try immunomodulators and Chinese herbal medicine
4. Molluscum contagiosa
[Cause] Molluscum contagiosum virus (MCV): Children are all caused by MCV-1 type, and those with low immunity are mostly caused by MCV-2 type; spread through direct contact, and can also be self-inoculated
[Clinical manifestations] More common in children and young people; initially appear as hemispherical papules the size of millet grains to mung beans, with waxy luster, umbilical concavity, and hard texture; then gradually become softer, grayish white/pearl color, with a small white dot in the center, and Cheese-like substances (molluscum bodies) can be squeezed out after rupture; the course of the disease is slow, self-limiting, and no scars are left after recovery; generally there are no symptoms, but secondary bacterial infection or eczematous dermatitis can often occur
[Treatment] After squeezing out the molluscum body, apply 33.3% trichloroacetic acid solution into the wart to cure it in one go.
5. Hand-foot-mouth disease
[Cause] Coxsackievirus A16 (the most common), EV-71; mainly transmitted through the fecal-oral route
[Clinical manifestations] Most common in 2 to 10 years old; the incubation period is 3 to 7 days. There may be prodromal symptoms of varying degrees before the rash. Skin lesions appear on the hands, feet, and mouth 1 to 3 days later. It starts as a red macule and soon develops into The blister is 2~4mm in size, with thin walls, clear blister fluid, and is surrounded by redness. After rupture, it can form a gray-white eroded surface/shallow ulcer; the skin lesions can occur on the hands, feet, and mouth at the same time, or they can be incomplete. However, oral involvement is the most common; the course of the disease is about 1 week, and recurrence is rare after recovery.
Section 4 Animal Skin Disease - Scabies
[Cause] Scabies mites (Sarcoptes scabiei): Mainly human scabies mites, which are intraepidermal parasites. Their activities cause mechanical stimulation to the skin. They themselves and their secretions can cause allergic reactions. They are mainly transmitted through direct close contact; there are also animal scabies. Mites, symptoms in humans after infection are mild and self-limiting
[Clinical manifestations] Collective infection, there are often patients with the same disease at home
Basic performance
It often occurs in thin and tender areas of the skin (especially between the fingers and vulva); the lesions are often symmetrical
Papules: the size of millet grains, light red/normal skin color, may have inflammatory blush
Papular herpes: the size of a millet grain
Tunnel: grey-white/light black with light lines, curved and slightly raised, and there may be papules/small blisters at the end, where the female worms stay; sometimes it can become atypical due to scratching/secondary lesions
Extreme itching, especially at night; scratching can cause scabs, eczema-like lesions and secondary infection
special type
Bullous scabies: mainly bullae; seen in highly sensitive people (such as infants and young children)
Scabies nodules: reddish-brown mung bean to soybean-sized hemispherical hard nodules may appear on the scrotum and penis of men, and around the anus/armpit of infants and young children. They are extremely itchy; they are foreign body reactions caused by the death of scabies mites.
Crusted scabies/Norwegian scabies: Occurs in patients with sensory neuropathy/severe disability due to inability to respond to itching/scratching; manifests as erythroderma-like lesions with yellow multilayered scales and verrucous crusts Contains a large number of scabies mites; highly contagious
[Inspection] Scabies mite inspection methods: ① Tunnel ink test; ② Needle pick method: Scabies mites can be found at the end of the tunnel and at the edge of fresh blisters; ③ Scratching method
[Treatment] 10~20% sulfur ointment, scabies drops, etc.; scabies nodules can be applied with glucocorticoids or injected with triamcinolone, and cryotherapy can be used if necessary; ivermectin is suitable for those that are ineffective in conventional external drug treatments. Scabies, crusted scabies, widespread or superinfected scabies