April 2005

Fig.3

Fig.4

Fig.5

Fig.6

Diagnosis: Follicular mucinosis (alopecia mucinosa)

Histopathology:Figures 1 and 2: Hypopigmented patches without scaling or follicular accentuation. Figure 3: H&E low power view of punch biopsy. Figure 4: H&E medium power view shows superficial perivascular and perifollicular lymphocytes.
Figure 5: H&E high power view shows lymphocytes within the follicular epithelium. Mucin is also appreciated in the follicles.
Figure 6: Colloidal iron stain highlights mucin within hair follicles. Specimen is signed out as follicular mucinosis without evidence of mycosis fungoides.

Discussion: Follicular mucinosis is characterzed histologically by mucin deposition within hair follicles. Although Kreibich in 19251 as well as Lehner and Szodoray in 19392 had described the finding of mucin in the infundibular and follicular epithelium, it was Pinkus in 19573 who first coined the term alopecia mucinosa. Since that time, alopecia mucinosa (which also became known as follicular mucinosis), have classically been divided into 2 groups: idiopathic and lymphoma-associated. Idiopathic follicular mucinosis occurs in a younger age group (children / young adults) and there are no association with cutaneous or extracutaneous disease. On the contrary, lymphoma-associated follicular mucinosis occurs in the elderly and is associated with mycosis fungoides or Sézary syndrome.

The task of differentiating between the 2 groups is difficult. Indeed, in a large case series of 44 patients with follicular mucinosis, Cerroni et al4 reported considerable overlap in age between the 2 groups. Furthermore, histopathological findings of both idiopathic and lymphoma-associated groups were initially identical, with the final designation possible only after long-term followup and the development of frank mycosis fungoides in the latter group. Lastly, PCR evidence of monoclonal T-cell receptor _ gene was present in approximately 50% of each group that were tested. The authors therefore concluded that idiopathic follicular mucinosis may represent a form of localized cutaneous T-cell lymphoma.

In the latest case series of follicular mucinosis, Böer et al5 examined 54 tissue samples from 45 patients, all of which were initially diagnosed as either follicular mucinosis or alopecia mucinosa. They made two observations. First, mucin deposits were found in the infundibular, follicular, and sebaceous epithelium and they coined the term "epithelial mucinosis." Second, they felt that all 45 patients met the histopathological diagnostic criteria of mycosis fungoides. They then concluded that "mycosis fungoides is not just an epidermotropic lymphoma, but an epitheliotropic lymphoma" and follicular mucinosis is a morphologic manifestation of mycosis fungoides.

The controversy regarding the classification of follicular mucinosis and its relationship to mycosis fungoides will undoubtedly continue until more research and better scientific tests are available.

The treatment of idiopathic follicular mucinosis is difficult and no consensus exists. Treatments that have been reported as successful include dapsone, indomethacin, interferon, isotretinoin, and minocycline.

1. Kreibich C. Mucin bei Hauterkrankungen. Archiv für Dermatologie und Syphilis. 1925;150:243-248.
2. Lehner E, Szodoray L. Ein ungewöhnlicher sich durch entzündliches Follikularödem auszeichnender Hautausschlag. Dermatol Wochenschr. 1939;108:679-685.
3. Pinkus H. Alopecia mucinosa, inflammatory plaques with alopecia characterized by root-sheath mucinosis. Arch Dermatol. 1957;76:419-426.
4. Cerroni L Fink-Puches R, Bäck B, et al. Follicular mucinosis. A critical reappraisal of clinicopathological features and association with mycosis fungoides and sezary syndrome. Arch Dermatol. 2002;138:182-189.
5. 4. Böer A, Guo Y, and Ackerman AB. Alopecia mucinosa is mycosis fungoides. Am J Dermatopathol. 2004;26:33-52.

6.Yotsumoto S, Uchimiya H, Kanzaki T. A case of follicular mucinosis treated successfully with minocycline. Br J Dermatol. 2000;142:841.

7.LeBoit PE. Alopecia mucinosa, inflammatory disease or mycosis fungoides: must we choose? And are there other choices? Am J Dermatopathol. 2004;26:167-170.

Thanks to Dr. Laurence Cheung for presenting this case.