[Follicular mucinosis in childhood: a case report and review of the literature].

Follicular mucinosis is defined as the accumulation of mucin in the follicular epithelium and sebaceous glands.1 It can present in isolation with an unknown etiology2 or in association with several conditions, including various types of hematologic malignancy. We report the case of an 8-year-old girl with no medical history of interest who was referred for a lesion on the dorsum of the nose that had appeared 2 months previously. She had been treated unsuccessfully with 1% hydrocortisone cream prescribed by her primary care physician. The lesion was a well-delimited, slow-growing, prominent, pruritic, and slightly infiltrated erythematous plaque (0.7 × 1 cm) with follicular hyperkeratosis (Fig. 1). The patient reported no history of injury, local infection, or insect bite and had no other lesions or palpable locoregional lymph nodes. Histopathology revealed several hair follicles with abundant intraepithelial mucin in the dermis, although there was no evidence of an inflammatory infiltrate or other signs of malignancy. The findings were compatible with a diagnosis of follicular mucinosis (Fig. 2). After administration of topical 1% methylprednisolone aceponate cream twice daily for 7 days, the lesion resolved completely, with no signs of recurrence after 1 year of follow-up. Follicular mucinosis was first reported by Pinkus3 in 1957 in a description of the histology findings for a series of patients with characteristic cutaneous lesions and mucin deposits in the hair follicles. The same year, Braun-Falco4 reported the first cases of follicular mucinosis associated with hematologic malignancies, specifically lymphoreticular malignancies. Emmerson and Coskey later established the current classification of the disease into 3 well-differentiated forms. The first type, known as benign follicular mucinosis, usually affects children and young adults and is generally not associated with comorbidity. The lesions are usually located on the face and tend to resolve spontaneously in a few months. The second type, lymphoma-associated follicular mucinosis, which comprises conditions such as mycosis fungoides or Sézary syndrome, differs from the first type in that it affects older patients (usually aged 40-70 years) and has a chronic course; there is no underlying systemic disease. The third type is follicular mucinosis, which is a manifestation of systemic malignancy and mainly affects elderly patients.5