Histopathology of Cutaneous Inflammatory Disorders in Children

Inflammatory dermatoses encompass a variety of histologic patterns that affect different portions of the skin. In spongiotic, psoriasiform, lichenoid, pityriasiform, and blistering disorders, there are predominately epidermal and junctional activities with variable superficial dermal inflammation. Hypersensitivity reactions can show either epidermal or mostly dermal changes depending on whether the exposure of the exogenous allergen occurs through an external or internal route, respectively. Exceptions include erythema multiforme and Stevens-Johnson syndrome/toxic epidermal necrolysis, where the etiology is often due to infection or ingested medications, but the histologic features are almost exclusively confined to the epidermis and dermoepidermal junction. Autoimmune disorders are unique in that lesions typically incorporate a mixture of epidermal and dermal inflammatory patterns with periadnexal inflammation, while the vast majority of vasculitis/vasculopathy and alopecia have changes limited to only the vessels and hair follicles, respectively. It is critical to recognize that a relatively limited number of histologic patterns are seen in a large array of clinical entities. Therefore, clinicopathologic correlation and careful examination of histologic details are of the utmost importance when evaluating skin biopsies for inflammatory disorders.

Neonatal eosinophilic pustulosis*

A pre-term, 7-week-old male infant presented with a recurrent pustular eruption involving his face and scalp with associated peripheral blood eosinophilia. Skin biopsy revealed spongiosis with numerous dermal and epidermal eosinophils without predominant follicular involvement. Immunohistology showed deposition of eosinophil granule major basic protein and eosinophil derived neurotoxin in the dermis and epidermis. He responded to conservative management. We discuss the differential diagnosis of neonatal eosinophilic pustular eruptions and suggest the term 'neonatal eosinophilic pustulosis' to best describe our case.

[Pustular diseases of the newborn]

In the newborn, there exists a wide spectrum of pustular skin diseases. These range from transitory, benign adaptation disorders up to systemic, life threatening illnesses. In 30-60% of newborns pustules are observed in association with the relatively harmless Erythema toxicum, the origin of which is still unknown today. It is necessary to differentiate this from the pustular diseases which may be of infectious or non-infectious nature and which require therapy. Typical pathogens include Malassezia furfur, Staphylococci, Streptococci, Candida spp. and the herpes virus group.

Eosinophilic Pustular Folliculitis in Infancy

In the standard literature of dermatology and dermatopathology "eosinophilic pustular folliculitis in infancy" is presented as a distinctive inflammatory disease of the skin, to wit, a variant of "Ofuji's eosinophilic folliculitis". Assessment critically of the first publication devoted to the subject revealed a potpourri of findings clinical and histopathologic, with no clear criteria being set forth by the authors to enable diagnosis, with precision. Our review of all articles dedicated to the matter of "eosinophilic pustular folliculitis in infancy" shows that criteria for diagnosis are found with great difficulty. The majority of patients reported on had neither "eosinophilic folliculitis," nor did they present themselves clinically in any way similar to what was originally described by Ofuji. The findings histopathologic told of most commonly were dense and diffuse infiltrates in the dermis that contained many eosinophils, sometimes with periadnexal distribution. We think that the findings reported on in several articles suggest that the patients more likely had a variety of different diseases, among them scabies, insect bites, impetigenized nummular dermatitis, and linear IgA-dermatosis. For clarification of terminology, we suggest that "eosinophilic folliculitis" is better defined as a pattern histopathologic than as a distinctive disease entity. It may be encountered in a variety of conditions (eg, Ofuji's disease, arthropod bites, scabies, or dermatophytosis). In sum, no clear criteria have been established for diagnosis of "eosinophilic pustular folliculitis of infancy" and there is no convincing evidence, at present, that "eosinophilic pustular folliculitis of infancy" qualifies as a distinctive inflammatory disease of the skin.

Neonatal eosinophilic pustular folliculitis

Eosinophilic pustular folliculitis (EPF) of infancy is a rare disorder which may begin in the neonatal period and cause considerable parental anxiety. It must be distinguished from other causes of a pustular eruption in neonates, including infection and erythema toxicum neonatorum, and rare disorders such as transient neonatal pustular melanosis, infantile acropustulosis and Langerhans' cell histiocytosis. Skin smears and occasionally skin biopsy may be necessary to reach a diagnosis. We report a case of a Caucasian child with an unusually early onset of EPF in the first day of life. We wish to emphasize the importance of recognizing this self-limiting condition in order to prevent inappropriate antimicrobial treatment.