Several factors may help identify aggressive mycosis fungoides

By David Douglas

NEW YORK (Reuters Health) - Factors including the density of perifollicular infiltrate may help to differentiate indolent and aggressive folliculotropic mycosis fungoides (FMF), according to Dutch researchers.

"While previously FMF had been considered as an aggressive type of MF, in (this) study we have differentiated between FMF patients with an indolent and aggressive disease course, based on clinical and histological features," Dr. Suzanne van Santen of Leiden University Medical Center told Reuters Health by email.

"These findings," she added, "may have therapeutic implications, since patients with indolent FMF might benefit from less aggressive skin-directed therapies."

As reported online June 8 in JAMA Dermatology, Dr. van Santen and colleagues studied 147 men and 56 women with FMF.

The 17 patients with histologically early plaque-stage FMF had a 10-year overall survival (OS) of 71%, very similar to the 80% seen in those with only patches and/or follicular papules.

The corresponding OS rate in the 41 patients with advanced plaque-stage FMF (25%) was almost identical to that of patients presenting with tumors (27%).

These and other findings led the researchers to identify three subgroups with significantly different survival. Early skin-limited FMF, seen in 84 patients, had an OS of 92% at five years and 72% at 10 years.

Corresponding proportions for advanced skin-limited FMF, seen in 102 patients, were 55% and 28%. For the 17 patients presenting with extracutaneous disease these were 23% and 2%.

Factors including sex, the extent of skin lesions and the duration of skin disease prior to diagnosis had no effect on survival or disease progression.

Independent risk factors for disease progression and poor survival were being older than 60 years at diagnosis, large cell transformation and the presence of extensive secondary bacterial infection.

The researchers conclude, "Clinical presentation and density of perifollicular infiltrate help to differentiate indolent FMF from aggressive FMF."

Dr. Peggy Wu of Beth Israel Deaconess Medical Center, Boston, told Reuters Health by email, "This large prospective cohort study . . . demonstrates what many of us have long suspected - that not all FMF is equal and the finding of folliculotropic tumor infiltrates is not enough to confer a worse prognosis."

"Folliculotropism and follicular mucinosis in the context of mycosis fungoides has been challenging to interpret in the current tumor-node-metastasis-blood staging and prognostic schema," added Dr. Wu, who is medical director of dermatology and was not involved in the study.

"This article," she concluded, "highlights the importance of clinicopathologic correlation in distinguishing between indolent and aggressive FMF, namely that a sparse infiltrate of malignant cells in the plaques behaves comparably to classic early stage (IA-IIA) MF whereas a higher density of folliculotropic neoplastic T cells portends a similar prognosis as tumor stage disease."

SOURCE: http://bit.ly/1XWDHeQ

JAMA Dermatol 2016.

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