Pagetoid reticulosis (Woringer-Kolopp disease) mimicking eczema: a case report with immunophenotypic analysis and literature review.

Pagetoid reticulosis (PR), also known as Woringer-Kolopp disease (WKD), is a rare subtype of cutaneous T-cell lymphoma. Due to its low incidence and non-specific clinical presentation, it is frequently prone to misdiagnosis. We report the case of a 53-year-old female with a 5-year history of a recalcitrant, pruritic erythematous plaque on the right ankle, initially mismanaged as chronic eczema. Clinical examination revealed a solitary, well-demarcated, infiltrated scaly plaque at an acral site. Histopathological analysis demonstrated striking epidermotropism of medium-sized atypical lymphocytes with a pagetoid distribution and Pautrier-like microabscesses. Immunohistochemistry (IHC) revealed a T-cell lineage (CD3+/CD5+) with significant loss of CD4, CD7, and predominantly absent CD2/CD8 expression. A Ki-67 proliferation index of approximately 40% and focal CD30 positivity were observed, while EBER in situ hybridization was negative. Following a definitive diagnosis of localized PR, the patient was treated with topical clobetasol propionate twice daily, resulting in substantial clinical resolution. Literature review highlights the marked immunophenotypic heterogeneity of WKD and its favorable prognosis in localized forms. For treatment-refractory acral plaques, a high index of clinical suspicion is paramount. Early biopsy with appropriate immunophenotypic evaluation is essential to avoid diagnostic delay and guide effective local treatment, including radiotherapy or surgical excision.