Follicular mucinosis. A reaction pattern in follicular epithelium.

Follicular mucinosis is a histologic term for a reaction pattern in follicular epithelium. Although it is the sine qua non for alopecia mucinosa as a disease sui generis, it may occur in a variety of unrelated conditions, which may be inflammatory, hamartomatous, hyperplastic, or neoplastic. Follicular mucinosis is rare in plaque and nodular lesions of mycosis fungoides, but when it occurs, the malignant lymphoma is not related to the condition known as alopecia mucinosa. In short, alopecia mucinosa is a wholly benign condition and is not premonitory or an early aspect of mycosis fungoides. Follicular mucinosis is not synonymous with alopecia mucinosa but is analogous to other histologic reaction patterns of cutaneous epithelium such as epidermolytic hyperkeratosis, focal acantholytic dyskeratosis, and cornoid lamellation.