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Follicular mucinosis is an uncommon inflammatory disorder characterized histologically by mucin accumulation in the follicular epithelium. The condition is generally divided into primary and secondary forms, the latter being frequently associated with mycosis fungoides. Lesional skin T-cell clonality has been documented in some patients with follicular mucinosis, even those with no histologic evidence of cutaneous lymphoma. In this report, we describe a patient with clonal idiopathic primary follicular mucinosis who had complete clinical, histologic, and molecular remission with minocycline therapy.

Follicular mycosis fungoides (FMF) is a recognized variant of mycosis fungoides. In this review, the authors characterize the distinct histopathological and immunohistochemical patterns of FMF that have been reported in the literature. This article is an extensive review of the literature cited in Medline and own data of the authors. The major patterns of FMF histopathology, immunohistochemistry, and molecular genetics are summarized in this review. Histologically, the quintessential finding in FMF is small to medium atypical CD3+ CD4+ CD8- T lymphocytes around and within the epithelium of the hair follicles. This finding is requisite to the diagnosis. However, this finding may be obscured by a host of other patterns often identified in FMF. This includes basaloid folliculo-lymphoid hyperplasia, a granulomatous reaction, eosinophilic folliculitis, and follicular cystic changes with subtle atypical lymphocytes in the cyst wall. Follicular mucinosis (MF) and syringo-tropism are also variably present. Immunohistochemistry of all reported cases uniformly show a CD4+ T cell infiltrate. This review emphasizes and discusses the broad spectrum of histologic changes which may be seen in FMF, clues to the diagnosis, and some potential mimickers.

Folliculotropic mycosis fungoides is associated with a worse prognosis than classical mycosis fungoides (MF), but whether this is due to resistance to skin-directed therapy or to biological differences is unclear. We discuss a case of a patient with folliculotropic MF (stage IIA) who progressed to develop Sézary syndrome (SS), stage IVB, over 6 years. A 40-year-old man presented with pruritic plaques affecting his head and trunk, characterized by follicular plugging. The histology was consistent with folliculotropic MF and T-cell gene analysis studies revealed a T-cell clone in the skin only. His condition gradually deteriorated and 5 years after presentation, T-cell gene analysis studies revealed the presence of a clone in the blood identical with that seen in the skin. His condition progressed with the development of erythrodermic disease and a leukaemic blood picture and he subsequently died of systemic nodal and visceral involvement. We present the first report detailing the stepwise progression of a patient with stage IIA folliculotropic MF to SS. This case demonstrates that MF and SS represent a clinical spectrum of the same disease.

The pathological features of alopecia areata were described in association with those of follicular mucinosis in the scalp pathology of an 18-year-old woman. The immunohistochemical picture of the inflammatory infiltrate showed a high CD4/CD8 ratio (25:1), which was significantly different from the CD4/CD8 ratio in patients with alopecia areata. The abundance of helper/inducer cells along with the involvement of the upper part of the hair follicles might explain the development of follicular mucinosis in this case. Different possibilities were discussed, but the clinical presentation and the follow-up favored the clinical and pathological interpretation of alopecia areata with incidental findings of follicular mucinosis.

Two patients with the benign type of follicular mucinosis (FM) are presented. Their clinical features and course were characteristic for this subgroup of FM. Light and electron microscopy, direct immunofluorescence, and immunoperoxidase cell marker studies were undertaken to characterize the nature of the disease process. Light microscopy confirmed the follicular outer root sheath and sebaceous gland epithelial degenerative changes. The infiltrating inflammatory cells were morphologically benign. Electron microscopy detailed the cellular associations in the areas of degenerative change. Disattached keratinocytes were closely apposed to significant numbers of macrophages and Langerhans cells. Direct immunofluorescence studies demonstrated primarily complement (C3) and fibrinogen/fibrin in areas of reticular degeneration. Immunoperoxidase studies revealed large numbers of T cells and macrophages and a striking increase in the number of Langerhans cells in the affected follicular epithelium. The findings suggest that cell-mediated immune mechanisms may play a role in the pathogenesis of this disorder.