Dermatophytosis And Other Sup... Health Article

There are three main forms of this condition. The first is a folliculitis on the back or upper part of the chest that consists of scattered follicular papules or pustules. These are itchy and often appear after sun exposure. In the second form, which is seen in patients with seborrheic dermatitis, there are numerous small follicular papules over the upper and lower portions of the back and chest. Erythema and greasy perifollicular scales are often seen in these patients. In the third form multiple pustules are seen on the trunk and face in patients with human immunodeficiency virus infection. This type is similar to the second form, and the patients usually have severe seborrheic dermatitis.

Scrapings or biopsy specimens from lesions show numerous yeasts occluding the mouths of follicles. Treatment with topical azole antifungals may be effective, but oral therapy with ketoconazole or itraconazole is often necessary.

In the early part of the 20th century, seborrheic dermatitis and dandruff of the scalp were thought to be caused by Malassezia yeasts because numerous organisms were present in skin scales. This view was subsequently superseded by the belief that the yeasts were secondary to a hyperproliferative state. However, evidence suggests that Malassezia is implicated in the pathogenesis of the condition. ⁵⁰

In most cases, seborrheic dermatitis responds to oral ketoconazole or topical azole antifungals. Improvement is associated with disappearance of the organisms, and relapse is associated with recolonization. Furthermore, the clinical appearances can be mimicked in animals with the application of both live and killed organisms to the skin. Some patients with seborrheic dermatitis have high antibody titers to Malassezia species.

It is unlikely that invasion of the epidermis is responsible for the appearance of seborrheic dermatitis, but an indirect disease mechanism such as sensitization or toxic damage is possible.

Seborrheic dermatitis can appear in any individual, although it is said to be particularly common in patients with neurologic disease, such as parkinsonism. In patients with AIDS, the onset of seborrheic dermatitis may be sudden and the rash more extensive than in other individuals. ⁵¹ The histology of seborrheic dermatitis is similar in all groups. Acanthosis and hyperkeratosis with elongation of dermal papillae are seen. An infiltrate of polymorphs in the epidermis above the dermal papillae is also often seen. Human immunodeficiency viruspositive patients tend to have more plasma cells in the infiltrate. These changes are similar to those seen in some forms of psoriasis.