Questions and Answers
What bacterial infection is characterized by honey-colored crusts and bullae?
Cellulitis is caused by a viral infection.
False
What viral infection causes cold sores and fever blisters?
Herpes Simplex Virus (HSV)
Dermatophytosis is a fungal infection of the skin, hair, and nails, caused by species of Trichophyton, Microsporum, and Epidermophyton. It can be further classified into Ringworm (Tinea corporis), Athlete's foot (Tinea pedis), and _________?
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What type of skin cancer develops from melanocytes?
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What percentage of skin cancer cases is melanoma responsible for?
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What are the four main subtypes of melanoma?
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What is the most common subtype of melanoma?
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Exposure to UV radiation during adulthood increases the risk of melanoma.
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What is the ABCDE rule used for?
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What is the typical diameter of a melanoma lesion?
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What is the primary treatment for melanoma?
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Dermatoscopy is a invasive diagnostic tool.
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Study Notes
Infectious Diseases in Skin Pathology
Bacterial Infections
-
Impetigo: a contagious skin infection caused by Staphylococcus aureus or Streptococcus pyogenes, characterized by honey-colored crusts and bullae
- Can be further classified into:
- Non-bullous impetigo: characterized by yellow-brown crusts and erosions
- Bullous impetigo: characterized by large, fragile blisters
- Can be further classified into:
-
Cellulitis: a bacterial infection of the skin and subcutaneous tissues, often caused by Streptococcus pyogenes or Staphylococcus aureus
- Presents as erythema, swelling, and warmth of the skin
-
Erysipelas: a bacterial infection of the skin and mucous membranes, caused by Streptococcus pyogenes
- Characterized by a shiny, erythematous, and edematous plaque with a well-defined border
Viral Infections
-
Herpes Simplex Virus (HSV): a viral infection that causes cold sores and fever blisters
- HSV-1: typically affects the face and lips
- HSV-2: typically affects the genitals and anogenital area
-
Human Papillomavirus (HPV): a viral infection that causes warts and papillomas
- Can be further classified into:
- Common warts (Verruca vulgaris)
- Plantar warts (Verruca plantaris)
- Genital warts (Condyloma acuminatum)
- Can be further classified into:
Fungal Infections
-
Dermatophytosis: a fungal infection of the skin, hair, and nails, caused by species of Trichophyton, Microsporum, and Epidermophyton
- Can be further classified into:
- Ringworm (Tinea corporis)
- Athlete's foot (Tinea pedis)
- Jock itch (Tinea cruris)
- Presents as annular, scaly plaques with a raised border
- Can be further classified into:
Parasitic Infections
-
Scabies: a parasitic infection caused by Sarcoptes scabiei, characterized by intense pruritus and a polymorphic rash
- Presents as papules, vesicles, and burrows in a linear or sergiginous pattern
-
Pediculosis: a parasitic infection caused by lice, characterized by intense pruritus and a rash
- Can be further classified into:
- Head lice (Pediculosis capitis)
- Body lice (Pediculosis corporis)
- Pubic lice (Pediculosis pubis)
- Can be further classified into:
Infectious Diseases in Skin Pathology
Bacterial Infections
-
Impetigo
- Caused by Staphylococcus aureus or Streptococcus pyogenes
- Characterized by honey-colored crusts and bullae
- Two types: non-bullous impetigo (yellow-brown crusts and erosions) and bullous impetigo (large, fragile blisters)
-
Cellulitis
- Bacterial infection of skin and subcutaneous tissues
- Often caused by Streptococcus pyogenes or Staphylococcus aureus
- Presents as erythema, swelling, and warmth of the skin
-
Erysipelas
- Bacterial infection of skin and mucous membranes
- Caused by Streptococcus pyogenes
- Characterized by a shiny, erythematous, and edematous plaque with a well-defined border
Viral Infections
-
Herpes Simplex Virus (HSV)
- Causes cold sores and fever blisters
- Two types: HSV-1 (affects face and lips) and HSV-2 (affects genitals and anogenital area)
-
Human Papillomavirus (HPV)
- Causes warts and papillomas
- Three types: common warts (Verruca vulgaris), plantar warts (Verruca plantaris), and genital warts (Condyloma acuminatum)
Fungal Infections
-
Dermatophytosis
- Fungal infection of skin, hair, and nails
- Caused by Trichophyton, Microsporum, and Epidermophyton species
- Three types: ringworm (Tinea corporis), athlete's foot (Tinea pedis), and jock itch (Tinea cruris)
- Presents as annular, scaly plaques with a raised border
Parasitic Infections
-
Scabies
- Caused by Sarcoptes scabiei
- Characterized by intense pruritus and a polymorphic rash
- Presents as papules, vesicles, and burrows in a linear or sergiginous pattern
-
Pediculosis
- Caused by lice
- Characterized by intense pruritus and a rash
- Three types: head lice (Pediculosis capitis), body lice (Pediculosis corporis), and pubic lice (Pediculosis pubis)
Melanoma
Definition and Classification
- Melanoma develops from melanocytes, responsible for skin pigmentation
- Accounts for 1% of skin cancer cases, but causes most skin cancer-related deaths
- Four main subtypes:
Subtypes of Melanoma
- Superficial Spreading Melanoma: most common (70% of cases)
- Nodular Melanoma: 15-20% of cases, characterized by rapid growth and vertical invasion
- Lentigo Maligna: 5-10% of cases, typically occurs on the face and grows slowly
- Acral Lentiginous Melanoma: rare, occurring on palms, soles, and nail beds
Risk Factors
- Ultraviolet (UV) radiation: exposure increases melanoma risk, especially during childhood and adolescence
- Genetic predisposition: family history of melanoma, especially in first-degree relatives
- Fair skin: individuals with fair skin, light hair, and light eyes are more susceptible
- Dysplastic nevi: presence of abnormal moles increases melanoma risk
- Weakened immune system: individuals with compromised immune systems are more susceptible
Clinical Features
-
ABCDE rule: diagnostic tool to identify melanoma:
- Asymmetry
- Border irregularity
- Color changes (multiple colors, especially black)
- Diameter > 6 mm
- Evolving (changes in size, shape, or color)
-
Lesion characteristics: melanoma lesions often appear as:
- Irregularly shaped or asymmetrical
- Multicolored or darkly pigmented
- Large (> 6 mm)
- Bleeding or crusting
- Itchy or painful
Diagnosis and Treatment
- Dermatoscopy: non-invasive diagnostic tool to examine the skin
- Biopsy: surgical procedure to remove a sample of the lesion for histopathological examination
- Surgical excision: primary treatment, involving removal of the lesion and surrounding tissue
- Adjuvant therapy: may include chemotherapy, radiation therapy, or immunotherapy for metastatic melanoma
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Description
This quiz covers bacterial infections of the skin, including impetigo and cellulitis, their causes, symptoms, and characteristics. Test your knowledge of skin pathology!
