Morphologic mimicry of cutaneous T-cell lymphoma as classic Hodgkin lymphoma-a case report.

BACKGROUND: Cutaneous T-cell lymphoma (CTCL) and classic Hodgkin lymphoma (cHL) are distinct lymphoid neoplasms with differing cells of origin and immunophenotypes. Morphological overlap between these entities can pose significant diagnostic challenges, particularly in patients with a concurrent or prior lymphoma diagnosis. CASE PRESENTATION: A 67-year-old male with a history of cHL and mycosis fungoides/lymphomatoid papulosis presented with new PET-positive right groin lymphadenopathy. Biopsy revealed atypical cells morphologically consistent with Hodgkin/Reed-Sternberg cells. However, clonal T-cell receptor beta gene rearrangement and immunophenotypic findings were inconsistent with cHL, and integration of these results with the patient's clinical history led to a final diagnosis of nodal involvement by CTCL. CONCLUSION: CTCL can morphologically mimic cHL, representing a significant diagnostic pitfall. This case underscores the critical role of immunophenotyping, molecular studies, and clinical context in accurately diagnosing complex hematolymphoid neoplasms.