WOOD'S LAMP EXAMINATION
When do I do it?
- In every patient with possible Microsporum canis infection (inflammatory and non-inflammatory alopecia)
What can I find?
- Fluorescing hairshafts
What do I need?
- Wood's lamp
How do I do it?
- Illuminate the affected area in a darkened room. In 50 - 60% of Microsporum canis infections there will be greenish fluorescence which runs along the hair shafts.
- In the case of negative results → perform a fungal culture using the McKenzie toothbrush technique (see: Fungal Culture, Tip).
- Pluck hairs with fluorescence along hair shafts and use them for trichoscopy and/or fungal culture.
- Cultures can be done in the clinic using a commercial DTM tube or plate or sent to an outside laboratory for culture.
- Drugs, soaps and bacteria (Pseudomonas sp.) or occasional individual scales can fluoresce as well, but they should not be associated with the hair shafts
- Be careful: A lack of fluorescent areas does not rule out dermatophytosis
A discrete swelling containing purulent material, typically in the subcutis
Absence of hair from areas where it is normally present; may be due to folliculitis, abnormal follicle cycling, or self-trauma
well-circumscribed, circular, patchy to coalescing alopecia, often associated with folliculitis
Regional subcutaneous edema
Ring-like arrangement of lesions
Thinning of the skin or other tissues
Fluid-filled elevation of epidermis, >1cm
Blood-filled elevation of epidermis, >1cm
dilated hair follicle filled with keratin, sebum
Dried exudate and keratinous debris on skin surface
Nodule that is epithelial-lined and contains fluid or solid material.
Extensive loss of pigment
Patches due to hemorrhage >1cm
Circular scale or crust with erythema, associated with folliculitis or ruptured pustules or vesicles
Defect in epidermis that does not penetrate basement membrane. Histopathology may be needed to differentiate from ulcer.
Red appearance of skin due to inflammation, capillary congestion
Thick crust often related to necrosis, trauma, or thermal/chemical burn
Erosions and/or ulcerations due to self-trauma
Excessive stratum corneum, confirmed via histopathology. This term is often used to describe the nasal planum and footpads.
Ulcer on skin surface that originates from and is contiguous with tracts extending into deeper, typically subcutaneous tissues
Accumulation of scale adherent to hair shaft
Increased melanin in skin, often secondary to inflammation
Partial pigment loss
Lack of hair due to genetic factors or defects in embryogenesis.
Lack of cutaneous pigment
Loss of hair pigment
Thickening of the epidermis, often due to chronic inflammation resulting in exaggerated texture
Flat lesion associated with color change <1cm
Increased melanin in skin, may be secondary to inflammation.
Multifocal, papular, crusting dermatitis; a descriptive term, not a diagnosis
A erythematous, macular, papular rash; the erythematous macules are typically 2-10 mm in diameter with coalescence to form larger lesions in some areas
A solid elevation >1cm
Abnormal nail morphology due to nail bed infection, inflammation, or trauma; may include: Onychogryphosis, Onychomadesis, Onychorrhexis, Onychoschizia
Abnormal claw curvature; secondary to nail bed inflammation or trauma
Claw sloughing due to nail bed inflammation or trauma
Claw fragmentation due to nail bed inflammation or trauma
Claw splitting due to nail bed inflammation or trauma
Solid elevation in skin ≤1cm
Solid elevation in skin ≤1cm
Inflammation of the nail fold
Flat lesion associated with color change >1cm
Small erythematous or violaceous lesions due to dermal bleeding
Venous dilation; most commonly associated with hypercortisolism
Flat-topped elevation >1cm formed of coalescing papules or dermal infiltration
Raised epidermal infiltration of pus
Net-like arrangement of lesions
Accumulation of loose fragments of stratum corneum
Fibrous tissue replacing damaged cutaneous and/or subcutaneous tissues
Undulating, serpentine (snake-like) arrangement of lesions
Permanent enlargement of vessels resulting in a red or violet lesion (rare)
A defect in epidermis that penetrates the basement membrane. Histopathology may be needed to differentiate from an erosion.
Wheals (steep-walled, circumscribed elevation in the skin due to edema ) due to hypersensitivity reaction
Fluid-filled elevation of epidermis, <1cm
Steep-walled, circumscribed elevation in the skin due to edema