Keratoderma-like T cell dyscrasia: A report of 13 cases and its distinction from mycosis fungoides palmaris et plantaris

Background: Atypical epitheliotropic T cell lymphocytic infiltrates are commonly encountered in routine and consultative dermatopathology practices and typically do not represent mycosis fungoides. Other conditions can mimic certain light microscopic and phenotypic findings encountered in mycosis fungoides, comprising a diverse spectrum of conditions including the lymphomatoid drug reaction, collagen vascular disease, viral hypersensitivity reactions and cutaneous T cell dyscrasia. Aims: To examine biopsies obtained from cutaneous T cell dyscrasia localized to the palms and soles and to evaluate whether it exhibits a morphologic and pathogenetic continuum with mycosis fungoides plantaris et palmaris. Methods: We examined 13 biopsies showing an epidermotropic superficial lymphocytic infiltrate from thirteen patients who presented with a palmar and/or plantar keratoderma without other sites of cutaneous involvement. Conventional light microscopy, immunophenotyping and clonality studies were carried out. The clinical features were recorded. Results: Biopsies showed a variably dense, superficial, angiocentric CD4 or CD8 dominant lymphocytic infiltrate accompanied by a non-destructive pattern of epidermotropism. Low-grade cerebriform atypia along with variable diminution in the expression of CD7 and CD62L was noted. In three cases, statins were suspected to be the cause. Due to lack of familiarity with the entity, treatment interventions were inconsistent and not aggressively pursued. There was no evidence of disease progression to mycosis fungoides in any case. Limitations: The limitations of this study include the lack of long-term follow up and information on the nature of the therapeutic interventions and responses to treatment. Conclusion: The spectrum of cutaneous lymphoid dyscrasias should be expanded to include cases manifesting as palmo-plantar keratoderma. These cases are to be distinguished from mycosis fungoides palmaris et plantaris. As with other forms of cutaneous lymphoid dyscrasia, the lesions tend to be persistent. The course however, is indolent in most cases.