Perianal, whitish, hard papules in an infant

A 5-month-old male infant in otherwise good general health was presented with newly developed, rapidly progressing whitish perianal lesions. The patient had a previous respiratory syncytial virus (RSV) infection and was unvaccinated. According to the mother, the lesions were asymptomatic. At the initial presentation to the pediatrician, the still markedly erythematous perianal skin prompted exclusion of perianal streptococcal dermatitis (smear result: local flora). A trial of topical combination therapy with corticosteroids and antibiotics resulted in a transient reduction of erythema; however, the whitish lesions persisted. During the first dermatological consultation, the application of olive oil was recommended, but no diagnosis was established. When the patient was referred for a second opinion and the lesions persisted, palpation revealed hard, whitish papules, some of which were arranged in a “spike-like” pattern around the anus, with slight surrounding erythema (Figure 1). It was not possible to wipe them off with a swab or compress. There were no signs of itching or pain in this area. Pictures provided by the mother showed an initially more pronounced finding (Figure 2). The only noteworthy finding in the medical history was a diagnosis of seborrheic dermatitis in the father. Your diagnosis? … Diagnosis: Infantile anogenital digitate keratoses (IADK) Infantile anogenital digitate keratoses is a noninfectious, asymptomatic keratinization disorder of unknown etiology, typically presenting in infancy with erythema and resolving spontaneously within a few months. Lesions are localized to the perianal region, with possible extension to the perigenital area. The condition predominantly affects male infants. It is characterized by whitish, hard keratoses, some of which are spinular or milium-like and, unlike pustules, do not open and cannot be removed by rubbing. Coexistence of finger-shaped papules and pseudo-pustules containing macerated keratin that can be opened by rubbing has been reported among the few cases described.1-3 Perianal eczema with superinfection (bacteria, Candida) is a possible differential diagnosis. In our patient, a biopsy was not performed due to the typical clinical findings. To date, twelve cases of IADK have been described in the literature, with the oldest case report still using the diagnosis of “multiple minute digitate hyperkeratosis”.4 In the case series by Bar-Ilan et al. one father was also affected by seborrheic dermatitis,1 as in our case. The two small case series suggest that this entity may occur more frequently than reported but often remains unrecognized and undescribed as such. None.