Fungi and yeasts can cause both superficial and deep infections in the skin with a great variation in clinical findings. In healthy hosts, commensal organisms such as candida remain superficial, whereas in the setting of an immunocompromised host they can be opportunistic, disseminated, and in some, lethal. Being familiar with both the common and uncommon fungi and yeasts and how they can present in the skin is important to allow for early diagnosis and treatment.
Dermatophyte infections in the skin are common, often pruritic, and almost always demonstrate persistent erythema and scaling of the affected regions. Tinea capitis can present with alopecia, broken hairs, localized or diffuse, fine scalp scaling, pustules, or painful boggy plaques with reactive cervical or occipital lymphadenopathy. Tinea, like other fungi and yeasts, tends to involve moist anatomic locations such as the body folds (axillae and groin) and the nail folds. Tinea corporis and faciei classically display the telltale annular or arcuate expanding patches or thin plaques with prominent scale at the leading edges. Appreciating this annularity can be difficult in some anatomic sites that are more convex or complicated such as around the ears or nose. Similarly difficult is when topical corticosteroids are used inadvertently on cutaneous dermatophyte infections resulting in a misleading clinical appearance with less scaling and erythema.
Candidal infections in the skin are also diverse, resulting in oral leukoplakia (thrush); the fissuring and erythema of the oral commissures known as angular cheilitis ; chronic paronychia; itching, erythema and white discharge of candidal vulvovaginitis; and the beefy red, erosive intertrigo of the folds with surrounding satellite pustules seen commonly in the diaper region of infants. In newborns, congenital candidiasis can take on multiple forms, including a widespread miliaria-like eruption, pustules, or erosions that are most likely self-limited in full-term patients, but can disseminate in those born prematurely.
Deep fungal and mold infections include those regional organisms that infect otherwise well patients, such as Histoplasmosis and Coccidiomycosis , and those opportunistic and ubiquitous pathogens such as Fusarium , Aspergillosis, and the zygomycoses. Although many of these fungi and molds can present with nonspecific skin lesions, including abscesses, ulcers, verrucous or hyperkeratotic plaques, or nodules with central crusts or eschars, some more specific eruptions are also seen with these infections. These more specific eruptions can be a clue to the underlying immune status of the patient, including erythema nodosum seen more commonly in immunocompetent patients with coccidiomycosis or histoplasmosis versus the disseminated molluscum-like papules seen more in immunocompromised patients with these same infections.