A case-control study of clinicopathologic features, prognosis, and therapeutic responses in patients with granulomatous mycosis fungoides

Background Granulomatous mycosis fungoides (GMF) is an uncommon variant of mycosis fungoides (MF). Objective We sought to analyze the relative frequency, clinicopathologic characteristics, prognosis, and therapeutic responses of GMF. Methods We conducted a retrospective case-control study of patients with GMF and age- and stage-matched patients with classic MF between 1981 and 2012. Results A total of 27 patients with GMF were identified, representing 6.3% of all patients with MF at our center. Skin manifestations were similar to classic MF having an atypical lichenoid CD4 + CD8 − lymphocytic infiltrate with interstitial histiocytes and/or perivascular granulomas with giant cells. Fewer patients with GMF achieved a partial response or complete response with topical (57% vs 83%; P  = .002) or ultraviolet light (62% vs 90%; P  = .006) therapy. The 5- and 10-year progression-free survival rates were significantly lower in patients with GMF (59% and 33%) compared with patients with classic MF (84% and 56%; P  = .02), but overall survival was similar between groups (86% and 72% vs 85% and 85%; P  = .54). Limitations The retrospective methodology may underestimate the frequency of GMF. The median follow-up time may be too short to detect possible differences in overall survival. Conclusion More frequent disease progression and poorer response to skin-directed therapies were observed in patients with GMF. Our findings may be helpful in selecting the most appropriate treatment for these patients.