Introduction

Granulomatous mycosis fungoides (GMF) is a rare variant of MF/cutaneous T-cell lymphoma (CTCL) characterized by epidermotropism and granulomatous infiltrates. Although an enhanced immune response associated with granulomatous formation may indicate a good prognosis in MF patients, cases with aggressive course have also been reported. Given the variable skin manifestations of GMF and the lack of typical patch/plaque lesions in some cases, we aimed to perform a clinical analysis of GMF patients focusing attention on clinical features and impact on prognosis.

Methods

In this single-center, observational retrospective study, medical charts of all GMF cases registered in our database from January 2011 to December 2020 were reviewed with regard to demographics, clinicopathological features, treatment modalities, follow-up, and outcomes.

Results

A total of 6 GMF cases (4 males, 2 females; mean age 65.6 years) were studied, representing 0.8% of all MF patients (n = 728) in our registry. Three distinct clinical patterns were recorded: cases with typical of classic MF lesions, consisting of erythematous, scaly, infiltrated plaques (n = 2); patients with typical and atypical MF lesions (n = 1), consisting of flat, red, scaly patches combined with dermatofibroma-like lesions (n = 1); and cases with exclusively atypical lesions (n = 3), mostly mimicking granulomatous disorders. The following atypical presentations were observed: granuloma annulare-like lesions (annular smooth papules and plaques with central clearing) (n = 1); sarcoid-like plaques with bluish-purple papules and ulcerative oral/genital lesions (n = 1); and psoriasiform plaques with rosacea-like lesions. Contrary to “classic” MF cases, all “atypical” cases showed a trend towards more rapid disease progression, thus poor prognosis, including two cases of CD30+ large cell transformation in either skin or extracutaneous (both nodal and central nervous system) sites and ultimately lymphoma-related death (n = 1).

Conclusions

This case series indicated that GMF can be associated with a range of skin lesions, both typical and atypical of ‘classic” MF. Among GMF cases, patients presenting with atypical lesions seemed to have a distinct, but usually worse, prognosis compared to patients with classic-type MF lesions, possibly reflecting the potential biologic differences of GMF. Further research is still needed to elucidate whether or not certain presentations may carry different prognostic implications, opening new perspectives for accurate disease classification.