Follicular cutaneous T-cell lymphoma: a clinicopathological study of nine cases

Nine patients with follicular cutaneous T-cell lymphoma (CTCL), a recently described variant of lymphoma, are presented. On the basis of clinical manifestations and disease course, three groups of patients were distinguished: (i) two patients with follicular CTCL not associated with conventional lesions of mycosis fungoides (MF) and showing no evolution towards MF in follow-up periods of 3 and 6 years; (ii) one patient; with follicular CTCL that evolved into conventional MF within 3 years; (iii) six patients showing conventional MF lesions either before or concurrently with the follicular lesions and thus representing follicular CTCL of the true MF type. The follicular lesions included hair-devoid patches or plaques with spiky hyperkeratotic papules (four patients), keratosis pilaris-like lesions (four), comedo-like lesions (four), follicular papules with alopecia (three) and milia-like lesions (three). Histopathological examination showed perifollicular and intrafollicular lymphocytes, without mucin deposition and with minimal or no involvement of the overlying epidermis. Significant syringotropism was also observed in three cases. Immunohistochemical analysis showed the predominance of CD4+ T cells, deletion of CD7 in some cases, Ki-67+ lymphocytes confined mainly to the follicular epithelium, and expression of keratinocyte intercellular adhesion molecule-1 exclusively in the hair follicle. T-cell receptor gamma gene rearrangement was positive in the one case studied from each group. Different treatment modalities were employed, the most commonly used as monotherapy being phototherapy: psoralen ultraviolet A in four patients, two of whom showed a complete clinical and histopathological remission, and ultraviolet B in one patient, who showed a complete remission (both clinical and histopathological). This study indicates that follicular CTCL is more common than reflected in the literature, has heterogeneous clinical manifestations, and is either an expression of or closely related to MF. The influence of the follicular involvement on the therapeutic response remains to be clarified. However, our therapeutic experience clearly suggests that some patients with follicular CTCL can benefit from phototherapy.