Follicular mucinosis and follicular mycosis fungoides: clinicopathological evaluation of seven cases.

OBJECTIVE Follicular mucinosis is a disease characterized by follicular degeneration and mucin accumulation. It can be seen in mycosis fungoides, although idiopathic or forms associated with other diseases are also known. Follicular mycosis fungoides is a type of mycosis fungoides with different clinicopathological and prognostic features. MATERIAL AND METHOD Seven cases with follicular centered lesions and multiple biopsies (2-6) were included. Cases were evaluated according to their clinical, histological and immunophenotypical features and follow-up data. RESULTS All cases were male, and the mean age was 40.3 (range 18-61). Clinical complaints were follicular prominence, erythema and alopecia at head and neck, trunk, and lower limbs. Follicular mucinosis (6/7), and dermal lymphoid infiltration showing minimal-intensive folliculotropism accompanied by eosinophils was seen. Lymphoid infiltration was composed of small-medium sized cells, with scattered hyperchromatic nuclei in six cases. In one case there was only minimal cytological atypia. Intense folliculotropism of atypical lymphocytes and dense dermal infiltration without follicular mucinosis was seen in one case. Local and/or systemic treatments were applied and partial remission was achieved histologically. In three cases new and increasing lesions were seen. Density of infiltration and atypia were increased. CONCLUSION The findings supported the opinion that follicular mucinosis is an important finding seen in mycosis fungoides. There can be important differences concerning the amount of infiltration and degree of atypia. In cases where the density of infiltration associated with follicular mucinosis is not diagnostic for MF, there can be progression over time. Long-term follow up is necessary in such cases where the differential diagnosis is difficult.