Hypopigmented CD8 + Mycosis Fungoides in Sri Lanka: Clinicopathologic Evidence for an Indolent Variant.

BACKGROUND

Mycosis fungoides (MF) is the most common primary cutaneous T-cell lymphoma and typically presents with erythematous or scaly patches in older adults with a CD4 + immunophenotype. In Sri Lanka, however, a hypopigmented variant with CD8 + predominance and an apparently indolent clinical course is frequently encountered.

METHODS

A retrospective descriptive study was conducted on 243 patients with histologically confirmed MF diagnosed at the National Hospital, Kandy, between 2018 and 2024. Clinical, histopathologic, and immunophenotypic features were reviewed in all cases. A subset of 27 patients with a minimum follow-up of 2 years was analyzed for treatment modalities and clinical outcomes. Diagnoses were established according to WHO-EORTC 2018 criteria.

RESULTS

Patients predominantly presented with hypopigmented patch-stage disease involving sun-protected sites. Histology showed subtle epidermotropism with small Pautrier microabscesses and a characteristic "eyeliner" pattern. Immunohistochemistry demonstrated a CD8 + -predominant infiltrate in 95.9% of cases, with absent or reduced CD4 expression. Most patients achieved complete or partial remission with topical therapy or phototherapy, and no progression to plaque or tumor stage was observed.

CONCLUSIONS

Hypopigmented CD8 + MF in Sri Lanka represents an indolent clinicopathologic variant within the MF spectrum, recognition of which is essential to avoid misdiagnosis and overtreatment.