Follicular mucinosis is a cutaneous disorder distinguished by the buildup of mucin in the sebaceous glands and the pilosebaceous follicles. It is associated with a number of diseases, including systemic lupus erythematosus, mycosis fungoides, and several dermatoses, but it may also arise as a separate clinical entity. The presence of single or multiple well-delineated erythematous plaques with alopecia is the typical presentation. Histological examination of the lesions is necessary to make the diagnosis.
Follicular mucinosis (also known as alopecia mucinosa) is a rare cutaneous disease characterized by the accumulation and deposition of mucin in hair follicles and sebaceous glands, with follicular keratinocytes being the presumable origin of excessive mucin    . The pathogenesis of follicular mucinosis is yet to be revealed, and the clinical presentation varies only slightly across different subtypes that have been described in the literature     
Because of the wide differential diagnosis that may be seen with follicular mucinosis, particularly in older adults, the physician must conduct a thorough clinical investigation. Firstly, the course of symptoms, their severity, as well as their progression or possible relapse should be assessed. It must be noted that some of the underlying etiologies (eg. mycosis fungoides) might develop before, after, or together with follicular mucinosis, which is why a detailed personal history is essential in revealing disease that can point to the causative illness  . A meticulous inspection of the skin that will allow detection of typical erythematous plaques and alopecia is perhaps even more important in narrowing the number of possible diagnoses. To confirm follicular mucinosis, however, a biopsy of the lesion and subsequent histopathological examination is necessary   . Confirmation of mucin deposition in the external root of the hair follicle and sebaceous glands and an abundant lymphocytic infiltrate in the follicles are main microscopic findings  . Many studies have attempted to find histological criteria that could differentiate between idiopathic and secondary forms of follicular mucinosis, but the appearance of both subtypes on histology is virtually identical  . Thus, the classification rests on clinical criteria and the ability of the physician to recognize main clinical features.