ALOPECIA MUCINOSA (FOLLICULAR MUCINOSIS)
Alopecia mucinosa occurs in two clinical forms, primary (idiopathic) and secondary (associated with variety of disorders including lymphomas, lupus erythematosus, and in the background of miscellaneous conditions).  The distinction is best made with the retrospectoscope. In general,  well-developed lesions on the head and neck of younger patients (less than age 40) in the absence of overt evidence of some other condition will be of the primary variety.

The condition is characterized histologically by the expansion of the follicle by increased acid-mucopolysaccharide (mucin) associated with shrinkage of the follicular keratinocytes. The shriveled keratinocytes interconnect in a syncytium. It should be noted that this type of change is seen to a minimal degree in many folliculoreactive processes, and the diagnosis of follicular mucinosis should only be considered when the changes are prominent.


This biopsy is from a large area of alopecia that is slightly indurated, erythematous, and minimally scaly. Two other smaller, similar foci are also present in the scalp. The patient is a 28 year old male. The patient has no overt evidence of a systemic disease.
 
Scan power view. All follicles are altered. Follicular plugging is present, but there are no keratinocyte alterations that would be suggestive of lupus erythematosus.
Low power view of the follicle located in the right side of the picture. There is bulbous expansion of the follicle, and there should be at least this much alteration to consider the diagnosis of alopecia mucinosa.
High power view of the above. A large amount of mucin (basophilic material) is deposited between shriveled epithelial cells that form a reticulated syncytium.

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