Tinea capitis is a superficial fungal infection caused by dermatophytes in the scalp and hair, mostly in children, and can be divided into tinea alba, black dot ringworm, tinea favus, and kerion on the basis of different pathogens and clinical manifestations.
The pathogens are mainly trichophyton tonsurans, microsporum canis, and microsporum audouinii, as well as other trichophytons, such as trichophyton schoenleinii and trichophyton violaceum.
Tinea capitis is mainly transmitted by direct or indirect contact with infected patients or animals, and individuals with trauma caused by haircuts are susceptible to infection. Therefore, haircut is one of transmission routes. However, tinea capitis may not occur after fungal infection, which is closely related to the body resistance to fungi. Most adults are more resistant than children, so tinea capitis is more common in children.
Signs and Symptoms
The manifestations of tinea capitis vary from non-inflammatory desquamation similar to seborrheic dermatitis to severe pustular rash with hair loss. Hair loss with or without scales is the most common manifestation of tinea capitis. Hair loss can be localized in the scattered patches or involved in the entire scalp. Posterior cervical or postauricular enlarged lymph nodes may be present.
Skin lesions are grayish white, round or oval, scaly patches, with or without satellite lesions. The hairs in the affected area are usually fractured 2 - 4 mm from the scalp, and are sheathed by white fungi. Subjective symptoms are generally absent, but mild pruritus may be occasionally present. The skin lesions generally do not extend anymore 6 months after onset, and are relatively stationary. During adolescence, the sebaceous glands develop and sebum secretion increases, and the disease tend to heal spontaneously as long-chain fatty acids inhibit fungal growth. If without secondary infection, there are not scars and baldness. Sometimes, the disease can be manifested by inflammatory papules, can progress into kerion in severe cases, and is often caused by contact with infected dogs, cats, and rabbits.
Figure 1 tinea alba
Black dot ringworm
Skin lesions of the illness are smaller in size and larger in amount compared to tibea alba., and generally there is no inflammatory reaction. The infected hairs are fractured once growing up from the scalp, and the residual hairs are in the follicular orifices, which are small black dots. There is mild pruritus or no subjective symptoms. After a long course of treatment, scars may remain after healing, causing focal baldness.
Figure 2 black dot ringworm
The illness occurs mainly in children, and can also be seen in adults and adolescents. Initial skin lesions are pustules or vesicles in the follicular orifices, gradually developing into yellow scabs. The base of the yellow scabs sticks tightly the peripheral follicular orifices, with hair penetration from the center. After removal of the crusts, there are red, slightly depressed erosion, often accompanied by rat urine-like odor. The infected hairs are dry, dull, and uneven. Generally, there is mild pruritus or no obvious subjective symptoms. If the condition persists for a long time, atrophy of the hair follicles and scalp may occur, resulting in large scars and permanent baldness.
Figure 3 tinea favus
Strong body reactions cause obvious infectious granulomatous reactions, and the typical manifestations are one to several, round, dark red, infiltrating or bulging, inflammatory masses, with clustered, small pustules on the surface, and small amounts of pus can be discharged when squeezing. The hairs in the affected area are loose. There may be different degrees of pain and tenderness, and regional lymph nodes are often enlarged. Scars often remain after healing, which can lead to permanent baldness. Sometimes, kerion presents with atypical clinical manifestations, especially in adults, and are easily misdiagnosed as abscesses.
Figure 4 kerion
Asymptomatic carriers have no symptoms of tinea capitis, but positive fungal culture is present, more common in school students or family members of patients. Appliances contaminated by the infected hairs are often the source of infection, and the illness can last for 6 weeks to 6 months if without treatment.
Tinea capitis can be diagnosed on the basis of clinical manifestations and microscopic examination of potassium hydroxide (KOH) with the scales or infected hairs. The size and morphology of spores inside or outside the hair shafts can help distinguish pathogens and guide treatment.
Tinea capitis caused by microsporum canis and microsporum audouinii is blueish green under a Wood lamp, and can be differentiated from erythrasma.
If necessary, fungal culture of the infected hairs can be performed. The rash on the scalp in children can be similar to abscesses, and culture may be needed.
Griseofulvin is still preferred and is most sensitive to microsporum. The treatment regimen is 0.6 - 0.8 g/d in adults, 15 - 20 mg / (kg.d) in children, orally after meals in 3 divided doses for 3 - 4 weeks. Ketoconazole is the most sensitive to trichophyton tonsurans, and the dose in children is 5mg / (kg.d) in single dose orally at meals for 4 - 8 weeks. Other treatment regimens are itraconazole 0.2 g/d in adults, 0.1 g/d in children, orally at meals once daily for 4 - 6 weeks and terbinafine 250 mg/d in adults, 125 mg/d in children, orally for 4 - 8 weeks. In the acute phase of kerion, a small dose of corticosteroids can also be indicated in a short term.
Common topical medications are 5% - 10% sulfur ointment, 2.5% iodine tincture, and 3% clotrimazole cream for 1 month. If with obvious inflammation, fungicides, such as 0.1% ethacridine, 1:4000 potassium permanganate solution, and 0.1% nitrofurazone, and topical antibiotic ointments, such as ciprofloxacin ointment, can be administered.
During treatment, daily hair wash with warm soapy water should be performed to remove scales and crusts, preventing from the extension of skin lesions. Thick crusts can be removed with 5% salicylic acid ointment before topical medication. Haircuts every 7 - 10 days are necessary.
Permanent hair loss and atrophic scars remain after healing in tinea favus.
There are neither scars nor permanent hair loss after healing in tinea alba.
Focal hair loss and spotted atrophic scars often remain after healing in black dot ringworm.
Scars and localized permanent hair loss remain after healing in kerion.
The hairs, scales, and crusts of the infected patients should be burned, and clothes contaminated by patients should be sterilized.