Some patients with mycosis fungoides present with follicular papules and plaques characterized histopathologically by abundant deposits of mucin within hair follicles that are surrounded by a more or less dense infiltrate of T lymphocytes (Figs 2.43 & 2.44) . The hair follicles are infiltrated by the lymphocytes (pilotropism). The epidermis between affected follicles may be spared or involved by the disease ('epidermal mucinosis') (Fig. 2.45). Alopecia resulting from destruction of the follicles is common (alopecia mucinosa), either generalized or localized (Fig. 2.46). Itching is severe and represents a major problem in this variant of mycosis fungoides, and may be non-responsive to standard treatments.
A variant of mycosis fungoides with marked involvement of the hair follicles but without deposition of mucin has also been described (pilotropic mycosis fungoides) (Fig. 2.47); its relationship with follicular mucinosis-associated mycosis fungoides is unclear, but it seems that pilotropic mycosis fungoides represents a distinct clinicopathological variant of the disease .
In patients with marked involvement of the hair follicles, with or without deposition of mucin, a localized eruption of small infundibular cysts and comedones infiltrated by neo-plastic T lymphocytes can be observed (mycosis fungoides with eruptive cysts and comedones) (Figs 2.48 & 2.49). The clinical picture is similar to that observed in 'milia en plaques'.
We believe that 'idiopathic generalized follicular mucinosis' represents a variant of mycosis fungoides with marked
Fig. 2.43 Mycosis fungoides with follicular mucinosis. Follicular erythematous papules and plaques on the thigh.
deposition of mucin within hair follicles, and cases of progression to late-stage mycosis fungoides and death have been well documented . We have also observed patients with clear-cut mycosis fungoides-associated follicular muci-nosis who went into clinical remission after conventional
treatments, and who subsequently relapsed with skin lesions showing clinical and histopathological features of 'idiopathic' follicular mucinosis, again suggesting that this condition represents a variant of mycosis fungoides. Even 'benign' localized follicular mucinosis may represent a variant of mycosis fungoides, conceptually and biologically similar to localized pagetoid reticulosis and 'unilesional' mycosis fungoides .
Some authors report a worse prognosis in mycosis fun-goides associated with follicular mucinosis in comparison to patients with 'common' mycosis fungoides .
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