What is alopecia mucinosa?

This term actually refers to two entirely different causes of hair loss. The conditions have in common a similar histologic finding—follicular mucinosis, the accumulation of mucin (acid mucopolysaccharides) within the follicular epithelium, resulting in hair damage and hair loss.

The first form of alopecia mucinosa is a benign condition found in young and otherwise healthy individuals. One or more oval or circular hairless patches or plaques are present, which can be hypopigmented or erythematous and may be scaly, eczematous, or studded with minute papules. The condition usually involves the head, neck, upper arms, or upper torso. Spontaneous resolution usually occurs in months to years.



The second form of alopecia mucinosa occurs in patients with mycosis fungoides, a form of cutaneous T-cell lymphoma. Patients are usually elderly, and numerous, often large, hairless, erythematous, and indurated plaques are found (Fig. 20-7). Histologically, follicular mucinosis is present, but an atypical lymphocytic infiltrate that often invades the epidermis and follicles is also seen. This atypical cellular infiltrate allows for the diagnosis of mycosis fungoides. The hairless lesions and histologic follicular mucinosis are merely manifestations of the underlying lymphoma.

Gibson LE, Brown HA, Pittelkow MR, Pujol RM: Follicular mucinosis, Arch Dermatol 138(12):1615, 2002.