Piedra

“Piedra” means “stone”, reflecting the fungal elements’ adherence to one another to form nodules along the hair shaft. Piedra is a superficial infection that begins under the cuticle of the hair and extends outward, which can lead to weakening and breakage of the hair. As the nodules enlarge, they can even envelope the hair shaft ( Fig. 77.1 ). The two major forms – black piedra and white piedra – are distinguished by their clinical appearance and findings on microscopic examination ( Table 77.4 ).

Causes of nodules on hair shafts.

Patients with black piedra develop asymptomatic brown to black nodules along the hair shaft. White piedra manifests with soft, less adherent nodules that are typically white but may also be red, green, or light brown in color. In addition to white piedra, Trichosporon spp., especially T. asahii , can cause trichosporonosis in immunocompromised patients. This serious systemic infection presents with fungemia, fever, pulmonary infiltrates, and skin lesions. The latter are typically papulovesicular and purpuric, often with central necrosis; another potential finding is creamy white plaques resembling the in vitro fungal colonies. Trichosporon endocarditis, usually involving prosthetic valves, can also occur.

Tinea nigra

After a 10- to 15-day incubation period, tinea nigra most commonly presents as a single, sharply marginated, brown to gray–green macule or patch that can be velvety or have mild scale ( Fig. 77.2 ). There are usually no associated symptoms (i.e. pruritus), and no predisposing factors have been identified. Although most frequently seen on the palms, tinea nigra can also appear on the soles, neck, and trunk. Palmoplantar lesions are said to resemble acquired acral melanocytic nevi, but the former are usually larger, lighter in color, and lack the linear striations of acral nevi . The advancing border of a tinea nigra lesion may also be more darkly pigmented than its center. While the disease tends to be chronic, recurrence after effective treatment is infrequent except in the case of re-exposure.

Tinea nigra.

Single, sharply demarcated brown macule on the finger.

Courtesy, Frank Samarin, MD.

Tinea (pityriasis) versicolor

Patients usually present with multiple oval-to-round macules, patches or thin plaques with mild, fine scale. Demonstration of this associated scale may require scratching or stretching the skin surface. The lesions are often confluent centrally within areas of involvement, which may be extensive. Seborrheic regions, in particular the upper trunk and shoulders, are the favored sites. Less frequently, lesions are seen on the face (especially in children), scalp, antecubital fossae, submammary region, and groin. Involvement of flexural areas is sometimes referred to as “inverse” tinea versicolor.

The most common colors are brown (hyperpigmented; Fig. 77.3A ) and whitish-tan (hypopigmented; Fig. 77.3B ); occasionally there is mild inflammation leading to a pink color ( Fig. 77.3C ). Hypopigmentation may be secondary to either reduced tanning or inhibition of melanin production by dicarboxylic acids that result from metabolism of skin surface lipids by the yeast. In general, tinea versicolor is asymptomatic and the major concern is its appearance.

Tinea (pityriasis) versicolor.

A Hyperpigmented variant with confluence on the lower chest. B Hypopigmented variant on the face. C Coalescing pink lesions with fine scale. D Yeast and short hyphal forms in the stratum corneum highlighted by a PAS stain (inset).

A, B, Courtesy, Kalman Watsky, MD; D, Courtesy, Lorenzo Cerroni, MD.

Malassezia ( Pityrosporum ) folliculitis

This condition is most commonly seen in young women and is characterized by pruritic, monomorphic follicular papules and pustules on the upper trunk, arms, neck and, occasionally, the face. It is due to excessive growth of M. furfur and M. globosa within the hair follicle, with resulting inflammation due to yeast products as well as free fatty acids generated by fungal lipases. Only yeast forms are observed, i.e. no hyphal forms as in tinea versicolor.

Tinea corporis

Tinea corporis is a dermatophyte infection of the skin of the trunk and extremities, excluding the hair, nails, palms, soles, and groin. The infection is generally restricted to the stratum corneum and most commonly affects exposed skin. Any dermatophyte can potentially cause tinea corporis, but T. rubrum is the most common pathogen worldwide, followed by T. mentagrophytes ( Table 77.8 ).

Tinea corporis can result from human-to-human (including autoinoculation, e.g. from tinea capitis or pedis), animal-to-human (often transmitted by domestic animals), or soil-to-human spread (see Table 77.7 ). Sources include occupational or recreational exposure (e.g. military housing, gymnasiums, locker rooms, outdoor activities, wrestling) and contact with contaminated clothing or furniture .

There are multiple clinical presentations of tinea corporis, and they can mimic other dermatologic conditions ( Table 77.9 ). As with most dermatophyte infections, the extent of inflammation depends on the causative pathogen and the immune response of the host. Because hair follicles serve as reservoirs for infection, hairier areas of the body may be more resistant to treatment.

The typical incubation period is 1 to 3 weeks. Infection spreads centrifugally from the point of skin invasion with central clearing of the fungus, typically resulting in annular lesions of varying sizes ( Fig. 77.6A–D ). Arcuate, circinate, concentric, and oval lesions can also develop ( Fig. 77.6D–F ). Although scale is usually present, it may be lessened or absent if topical corticosteroids have been used (tinea “incognito”). Pustules within the active border are suggestive of tinea (see Fig. 77.6E ). Lesions are occasionally vesicular, granulomatous, or verrucous ( Fig. 77.6G ). Associated symptoms may include pruritus and burning.

Tinea corporis.

A There is a subtle annular configuration with a border composed of individual, slightly scaly papules. B Classic annular lesion with a scaly raised border and central clearing. C Annular lesion with trailing scale reminiscent of erythema annulare centrifugum. D Multiple annular and circinate lesions of various sizes on the upper back. E Scaly concentric rings on the arm. F Pustules within multiple figurate lesions on the upper arm. G Inflammatory nodules on the dorsal hand and a thick granulomatous plaque on the distal forearm (tinea profunda). There is associated scale, including on the digits, and a few of the papulonodules are follicular (Majocchi granuloma).

B, D, Courtesy, Julie V Schaffer, MD. C, G Courtesy, Kalman Watsky, MD.

Tinea profunda, nodular perifolliculitis (including Majocchi granuloma), and tinea imbricata represent clinical variants of tinea corporis . Tinea profunda results from an excessive inflammatory response to a dermatophyte, analogous to a kerion on the scalp. It may have a granulomatous or verrucous appearance and be mistaken for cutaneous tuberculosis or a dimorphic fungal infection. Nodular perifolliculitis , usually caused by T. rubrum , is characterized by follicular papulopustules or granulomatous nodules that result from a deep dermatophyte folliculitis with disruption of the follicular wall ( Fig. 77.7 ). This variant is most commonly seen in women who have tinea pedis or onychomycosis and shave their legs, and it can also occur in the setting of immuno­suppression. The lesions may be extensive or even vegetating, and a prolonged granulomatous reaction (as described by Majocchi) can develop.

Nodular perifolliculitis (Majocchi granuloma).

Perifollicular inflammation and follicular pustules on the leg due to Trichophyton rubrum . A few of the lowermost papules have a granulomatous appearance.

Courtesy, Kalman Watsky, MD.

Tinea imbricata is a dermatophytosis caused by the anthropophilic dermatophyte T. concentricum . It causes chronic infections in an equatorial band encompassing the South Pacific, Asia, and Central and South America. The clinical presentation consists of concentric annular rings resembling erythema gyratum repens.

Tinea cruris

Tinea cruris is a dermatophyte infection of the inguinal region, in particular the inner aspects of the upper thighs ( Fig. 77.8 ) and crural folds, with occasional extension onto the abdomen and buttocks. The three most common causative agents are Epidermophyton floccosum , T. rubrum , and T. mentagrophytes ( Table 77.10 ).

Tinea cruris.

A thin, “broken-up” erythematous plaque with an arciform papular border on the upper inner thigh.

This condition is more often seen in men than in women, since the scrotum provides a warm and moist environment that encourages fungal growth and men are more likely to have tinea pedis and onychomycosis as a source of dermatophytes. Other predisposing factors include obesity and excessive perspiration. Tinea cruris is frequently associated with tinea pedis because clothing that is brought over the feet is contaminated and then comes in contact with skin in the groin region.

The initial sign of infection is usually an area of erythema and pruritus in the fold between the scrotum and the inner thigh. Characteristic lesions are sharply demarcated with a raised, erythematous, scaly advancing border that may contain pustules or even vesicles. Lesions can initially be circinate and then become serpiginous. The disease may remain unilateral or become bilateral.

The duration of infection depends on the causative pathogen. Infections with T. rubrum and many other anthropophilic species tend to be chronic, sometimes with leathery and lichenified lesions. In contrast, the zoophilic form of T. mentagrophytes (previously T. mentagrophytes var. mentagrophytes ) and other animal-acquired strains often cause acute infections with a prominent inflammatory component that may include pustules and vesicles (see Table 77.10 ). The scrotum itself is generally spared in tinea cruris. If the scrotum is involved or there are erosions or satellite pustules, cutaneous candidiasis should be considered. Measures to prevent recurrences of tinea cruris include wearing loose clothing, drying thoroughly after bathing, using topical powders, weight reduction (if obese), laundering contaminated clothing and linens, and treating concomitant tinea pedis.

Tinea manuum

Dermatophyte infections on the dorsal aspect of the hand have a clinical presentation similar to tinea corporis. However, dermatophyte infection of the palm and interdigital spaces has distinct characteristics and is referred to as tinea manuum. The reason for the two different clinical pictures is thought to be related to the lack of sebaceous glands on the palms. The typical causative organisms are the same as those for tinea pedis and tinea cruris: T. rubrum , T. mentagrophytes , and E. floccosum . Infections with Neoscytalidium dimidiatum and N. hyalinum , two non-dermatophyte fungi, can have a tinea manuum-like appearance.

Moccasin-type tinea pedis is often present in patients with tinea manuum, and the two share clinical features such as chronicity and hyperkeratosis. Tinea manuum is usually non-inflammatory and often unilateral (“two feet and one hand syndrome”) ( Fig. 77.9 ; see Fig. 77.15A ); there is hyperkeratosis of the palms and digits, including within creases, that fails to respond to emollients . Tinea unguium of the involved hand can serve as a clue to the diagnosis, but infection of all the fingernails is uncommon. Other presentations include exfoliative, vesicular, and papular variants. The differential diagnosis may include psoriasis, irritant or allergic contact dermatitis, dyshidrosis, and a “dermatophytid” reaction.

Tinea manuum.

A Diffuse scaling of the palm of one hand, with accentuation in the creases. B Multiple collarettes of scale reminiscent of keratolysis exfoliativa on one palm.

Tinea barbae

Tinea barbae is a dermatophytosis that involves the bearded areas of the face and neck in men. Because the disease is often acquired from animals, the causative organisms are typically zoophilic dermatophytes, namely T. mentagrophytes and T. verrucosum . Infection with Microsporum canis or T. rubrum is uncommon. In some geographic regions, other anthropophilic dermatophytes ( T. schoenleinii, T. violaceum , and T. megninii ) are endemic and cause tinea barbae. With the increased use of disposable razors and disinfectants, the incidence of tinea due to contaminated razors in barbershops has been dramatically reduced.

Since zoophilic organisms are the most common culprit and affected areas often have a large number of terminal hair follicles, the clinical presentation tends to be severe, with intense inflammation and multiple follicular pustules. Abscesses, sinus tracts, bacterial superinfection, and kerion-like boggy plaques can develop. Patients may have constitutional symptoms such as malaise as well as lymphadenopathy and even scarring alopecia. A second type of tinea barbae is superficial, less inflammatory, and similar to tinea corporis; T. rubrum is usually the causative agent in this variant ( Fig. 77.10 ). Alopecia may be present in the center of the lesion, but it is reversible. Other conditions that can mimic tinea barbae include bacterial folliculitis, viral infections (herpes simplex or zoster), acne vulgaris, cervicofacial actinomycosis, and a dental sinus tract. Spontaneous resolution may occur if all of the infected hairs fall out.

Superficial form of tinea barbae due to Trichophyton rubrum .

Several follicular pustules are evident.

Courtesy, Jean L Bolognia, MD.

Tinea faciei

While some dermatophyte infections of the face have classic features, e.g. scale, annular configuration, pustules in the border, others can be more difficult to diagnose clinically and require a high index of suspicion ( Fig. 77.11 , Table 77.9 ).

Tinea faciei.

A Erythema and scale on the nose and philtrum of a young child. The location and lack of central clearing may lead to the misdiagnosis of dermatitis with secondary impetiginization. B Child with pink papules, a few tiny pustules, and thin annular and arcuate scaly plaques in a perinasal and perioral distribution. These clinical findings could be mistaken for periorificial dermatitis. C Hyperpigmented lesions with subtle arcuate and annular configurations in a woman with darkly pigmented skin. There is minimal scale following the use of topical corticosteroids (“tinea incognito”). The clue to the application of topical corticosteroids is the relative hypopigmentation as compared with the more medial cheek.

A, Courtesy, Julie V Schaffer, MD; B, Courtesy, Antonio Torrelo, MD; C, Courtesy, Kalman Watsky, MD.

Tinea capitis

Tinea capitis is a common dermatophyte infection of the scalp in children ( Fig. 77.12 ), whereas adult infection occurs infrequently. The causative pathogens are members of only two genera: Trichophyton and Microsporum . T. tonsurans is currently the most common cause of tinea capitis in the US (accounting for >90% of cases), with a predilection for individuals of African descent , and M. canis is the second most frequent etiology. Globally, there is significant variation in the epidemiology of tinea capitis. While M. canis is a common cause in many countries, T. tonsurans has emerged as a major agent in Europe and elsewhere. The incidence of tinea capitis due to T. violaceum , which is endemic in Africa, has also recently increased in some areas of the US and Europe (especially western and Mediterranean regions), likely reflecting immigration patterns. The anthropophilic dermatophyte M. audouinii , which was once common and then subsequently diminished secondary to social and therapeutic advances, has more recently reappeared in Europe and may also potentially re-emerge in the US.

Tinea capitis.

The range of clinical presentations of tinea capitis due to Trichophyton tonsurans , from mild scalp scaling ( A ) to patchy alopecia with black dots ( B ) or scale ( C ) to large areas of alopecia with pustules and scale-crust ( D ). E Kerion formation due to T. tonsurans. F Microscopic examination of involved hairs demonstrates an endothrix pattern (KOH–chlorazol black stain). G Histologic examination shows arthroconidia and hyphae within hair shafts to the level of Adamson’s fringe (limit of the zone of keratinization; inset).

B, Courtesy, Louis A Fragola, Jr, MD; G, Courtesy, Lorenzo Cerroni, MD.

Different clinical presentations arise from the various causative organisms. For example, T. tonsurans causes an endothrix infection (see below), which classically results in “black dot” tinea capitis due to hair breakage near the scalp. In contrast, M. audouinii is an ectothrix form of tinea capitis that typically presents with dry, scaly patches of alopecia (“gray patch” tinea capitis). Both the pathogenicity of the culprit organism and the host immune response are factors that determine the severity of disease. Tinea capitis can range from non-inflammatory scaling that resembles seborrheic dermatitis (especially with T. tonsurans ; Fig. 77.12A ) to a severe pustular reaction with alopecia, known as a kerion. Alopecia with or without obvious scale is the most common presentation of tinea capitis ( Fig. 77.12B–D ). The alopecia may occur in discrete patches or involve the entire scalp. Use of dermoscopy can highlight “comma”, “corkscrew”, and dystrophic broken hairs that represent clues to the diagnosis of tinea capitis (see Ch. 69 ) . Many patients have posterior cervical and posterior auricular lymphadeno­pathy, which is helpful in differentiating tinea capitis from less inflammatory causes of alopecia, such as alopecia areata.

A kerion results from advanced disease coupled with an exaggerated host response that leads to boggy, purulent plaques with abscess formation and associated alopecia ( Fig. 77.12E ). Some patients may even become systemically ill with extensive lymphadenopathy. The hair in the affected area usually returns, but the longer the infection persists, the more likely the alopecia will be permanent. If a kerion is misdiagnosed as a bacterial abscess and treated with antibiotics following incision and drainage, the infection will likely worsen, thereby increasing the likelihood of scarring alopecia.

The “carrier state” of T. tonsurans refers to a clinical situation in which there are no obvious signs or symptoms of a scalp infection, yet a positive fungal culture is obtained. Although also seen in children, this typically occurs in adults who have been exposed to infected children. The carriers shed the fungus and are considered contagious . Consequently, some experts advocate treating all carriers with oral or topical antifungals.

For those dermatophytes that invade hair, three patterns of invasion exist: endothrix, ectothrix, and favus ( Fig. 77.13 ):

• •
  

  The endothrix pattern results from infection with anthropophilic fungi in the genus Trichophyton and is characterized by non-fluorescent arthroconidia within the hair shaft ( Fig. 77.12F ). The clinical presentation varies from scaling to “black dots” with patchy alopecia to kerion formation. T. tonsurans and T. violaceum are important causes of endothrix infection.

  
  
• •
  

  The ectothrix pattern occurs when arthroconidia are formed from fragmented hyphae outside the hair shaft (see Fig. 77.13 ). Cuticle destruction ensues. Ectothrix infection can be fluorescent ( Microsporum ) or non-fluorescent ( Microsporum and Trichophyton ), as determined by Wood’s lamp examination. Clinical features vary from patchy, scaly alopecia with little inflammation that may mimic alopecia areata to kerion formation.

  
  
• •
  

  Favus is the most severe form of dermatophyte hair infection and is most frequently caused by T. schoenleinii . Hyphae and air spaces are observed within the hair shaft, and a bluish-white fluorescence by Wood’s light examination is typically seen. Favus presents as thick, yellow crusts composed of hyphae and skin debris (“scutula”). Scarring alopecia may develop in chronic infections ( Fig. 77.14 ).

  
  

  
  

  
  

  

  
  

  
  

  Favus due to Trichophyton schoenleinii .

  
  

  Scarring alopecia with erosions and several scutula on the occipital scalp. The latter represent masses of keratin plus fungi.

  
  

  Courtesy, Israel Dvoretzky, MD.

  
  

The three patterns of hair invasion and the causative dermatophytes.

Tinea pedis

Tinea pedis is a dermatophyte infection of the soles and interdigital web spaces of the feet. Infection of the dorsal aspect of the foot is considered tinea corporis. The feet are the most common location for dermatophyte infections, and the majority of the US adult population has experienced tinea pedis. This condition is more common in adults than children and is found around the world, affecting both sexes. The lack of sebaceous glands and the moist environment created by occlusive shoes are important factors in the development of tinea pedis . In fact, tinea pedis is uncommon in populations that do not wear shoes. However, the fungus may be acquired from going barefoot (locker rooms, gyms, public facilities).

The dermatophytes that are typically responsible for tinea pedis are T. rubrum , T. interdigitale (previously T. mentagrophytes var. interdigitale), T. mentagrophytes , E. floccosum , and T. tonsurans (in children). Non-dermatophyte pathogens that produce clinical findings identical with tinea pedis include Neoscytalidium dimidiatum and N. hyalinum (moccasin and interdigital types) and, occasionally, Candida spp. (interdigital type). There are four major clinical types of tinea pedis, as outlined in Table 77.11 : moccasin ( Fig. 77.15A ), interdigital ( Fig. 77.15B ), inflammatory ( Fig. 77.15C ), and ulcerative. Each type has different associated morbidities and complications that can affect diagnostic considerations and therapeutic options. These include bacterial superinfection (the “dermatophytosis complex”), dermatophytid reactions, cellulitis (especially in patients who have venous hypertension, harvested saphenous veins, and chronic edema), and even osteomyelitis leading to amputation in diabetics. Other conditions that can mimic tinea pedis are listed in Table 77.9 . KOH examination and culture easily differentiate the moccasin and inflammatory forms of tinea pedis from these entities . Erythrasma can be diagnosed with Wood’s light examination because of its “coral red” fluorescence. Oral antifungal therapy should be considered in diabetics, immunocompromised patients, and those with moccasin-type tinea pedis. Finally, other dermatophyte infections often occur together with tinea pedis – in particular, tinea cruris, onychomycosis, and tinea manuum – and these sites should be examined ( Fig. 77.16 ).

Table 77.11

The four major types of “tinea pedis” caused by dermatophytes and non-dermatophytes.

 

Tinea pedis.

A Diffuse scaling on both feet (moccasin type) as well as on the right hand, representing “one hand–two feet” tinea. B Maceration between the third and fourth toes in the interdigital form. C Erythema, scale-crust, and bullae in the inflammatory form. D Extension of tinea pedis onto the dorsal foot in a serpiginous configuration of erythema and papules. Scale is minimal due to the patient’s use of a potent topical corticosteroid for presumed dermatitis.

B, Courtesy, Jean L Bolognia, MD; D, Courtesy, Julie V Schaffer, MD.

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