Psoriasis in patients with mycosis fungoides: a clinicopathological study of 25 patients.

BACKGROUND: It has been reported that patients with psoriasis are at increased risk for developing lymphoma including cutaneous T-cell lymphomas (CTCL). However, the comorbidity and the histopathologic correlation of psoriasis and mycosis fungoides (MF) have been less studied.

OBJECTIVE: The objective of this study was to investigate the relation between MF and psoriasis.

METHODS: We retrospectively reviewed and re-evaluated all MF cases diagnosed and followed in a 16-year period who carried both MF and psoriasis diagnoses.

RESULTS: Forty-one of 321 MF patients was the rate of psoriasis' comorbidity according to medical records. Twenty-five patients (7.8%) finally met the inclusion criteria. The rest were excluded due to inadequate evidence. Twenty patients had psoriatic lesions at the time of MF diagnosis. In 23 patients, there was histological confirmation of both diseases. Six patients (24%) were diagnosed with folliculotropic MF, two were diagnosed with pustular psoriasis, and six patients were affected by palmoplantar and nail psoriasis. In four patients, there was a very short time interval between MF and psoriasis diagnosis. Fourteen patients with psoriasis had been previously treated with immunomodulatory regimens. Interestingly, in eight patients, typical histological findings of both diseases were detected in the same biopsy specimen.

CONCLUSION: Our results support the opinion that the association between psoriasis and MF does exist. It is most possibly related to the chronic lymphocyte stimulation that occurs during psoriasis that eventually leads to a dominant clone and the evolution to CTCL. Our study suggests that apart from cases of early MF, which are being indeed misdiagnosed as psoriasis, there is another group of patients, where psoriasis truly coexists with - or even progresses to - MF.