Follicular Mucinosis Presenting as an Acneiform Eruption: A Follow-up Study

: It has been proposed by many authors that follicular mucinosis is directly associated with mycosis fungoides (MF). Follicular mucinosis may be classified into 3 main clinical variants: a benign idiopathic form in children and young adults, which includes an acneiform presentation; an idiopathic form in older patients with a benign course; and a third variant that occurs in adults and is associated with MF. Our goal was to study the relationship between the acneiform variant of follicular mucinosis and MF. Eight patients previously diagnosed with the acneiform variant of follicular mucinosis were identified. Biopsy specimens were reviewed to evaluate the histopathologic attributes that characterize the disease and the infiltrate's immunohistochemistry. Also, patient follow-up was assessed to evaluate the clinical course of the disease. Median age of onset of disease was 29.5 years; 95% of lesions were located in the head and neck region. Biopsy specimens showed a moderate to dense perivascular, perifollicular, and interstitial infiltrate of lymphocytes with mucinous deposits within the follicular epithelium. On immunohistochemistry, the infiltrate showed prominent leukocyte common antigen (LCA) positivity and a CD3-positive and CD4-positive infiltrate with rare CD20-positive cells. None of the study patients showed evidence of MF after a mean follow-up of 3 years. The benign course of disease demonstrated in the study patients suggests that the acneiform variant of follicular mucinosis probably represents a subpopulation of the benign idiopathic form of the disease. However, given that histopathologically this variant cannot be distinguished from the lymphoma-associated variant of follicular mucinosis, longitudinal evaluation is still warranted in these patients.