Abstract:

A 67-year-old male presented for further management after an outside biopsy revealed mycosis fungoides (MF). He reported a two-year history of red, pruritic plaques and patches initially starting on his back and spreading outwards. At consultation, examination revealed well-defined, erythematous, scaly plaques affecting approximately 13% body surface area. Histopathology and immunohistochemistry from two biopsies confirmed CD8+ MF, and T-cell receptor (TCR) gene rearrangement was positive for clonality. He was staged as IB and began narrow-band ultraviolet-B (nbUVB) therapy 3 times weekly and augmented betamethasone dipropionate daily. After 21 weeks of treatment, areas of rash were mildly improved, and he reported a new plaque on the posterior right ear, which was attributed to pressure from his glasses and masks. On recheck, the plaque had thickened, which prompted biopsy. Histopathology and immunohistochemistry confirmed CD4+ MF with TCR gene rearrangement showing clonality identical to prior biopsy sample, supporting a single clonal proliferation with different phenotypes. This case demonstrates the rare phenomenon of immunophenotypic shift in MF. Of reported cases, a CD4+ to CD8+ shift predominates with a single report of CD8+ to CD4+ shift occurring in primary cutaneous peripheral T-cell lymphoma. The overall prognosis for immunophenotypic shifting in MF is guarded, with published reports suggesting this phenomenon is associated with a more aggressive disease. Our patient has had only mild improvement with continued nbUVB and topical steroids, and mechlorethamine was prescribed but was unaffordable. Given the limited treatment options and inadequate response to therapy, he was referred to the closest T-cell lymphoma clinic for further management.

Financial Disclosure:
No current or relevant financial relationships exist.

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Jane Gay