Clinical and histopathologic spectrum of alopecia mucinosa/follicular mucinosis and its natural history in children

Background: Some authorities consider alopecia mucinosa (AM)/follicular mucinosis (FM) to invariably represent mycosis fungoides (MF). This understanding of AM/FM derives from observations in adults. Objectives: We sought to explore the clinicopathologic features and natural history of pediatric AM/FM. Methods: Medical records were searched for children given the diagnosis of AM/FM from 1998 through 2009. Diagnosis of AM/FM was defined as the presence of well-demarcated hairless plaques with follicular prominence plus an abundance of mucin on histopathologic examination. Results: Forty children with a clinical diagnosis of AM/FM were identified. Nine did not meet the inclusion criteria. In the 31 remaining cases (16 boys, 15 girls) the mean age at onset was 9 ± 3.5 years. Histopathologic examination showed folliculotropism in 28 patients (90%) and epidermotropism in 15 (48%). Twelve cases fulfilled the International Society of Cutaneous Lymphomas (ISCL) diagnostic criteria for early MF. The histopathologic findings were typical of MF in only in two of these cases. T-cell receptor gene rearrangement was positive in 3 of 6 (50%) of tested samples, one in a patient who fulfilled the ISCL criteria for early MF. Mean duration of follow-up was 6.2 ± 3.7 years. All skin lesions resolved and none persisted or recurred. Hodgkin lymphoma was diagnosed 6 months after diagnosis of AM/FM in one patient. Limitations: This was a retrospective study. Conclusions: Although some pediatric cases meet the diagnostic criteria for MF, AM/FM cannot be regarded unequivocally as early follicular MF in this age group. We suggest the current diagnostic criteria for early MF should exclude children with AM/FM. Long-term follow-up of children with AM/FM is nevertheless warranted.