Abstract
BACKGROUND: Mantle cell lymphoma (MCL) is an aggressive B-cell non-Hodgkin lymphoma that rarely presents with cutaneous involvement, which typically occurs in advanced disease stages. Primary cutaneous manifestations are particularly uncommon and frequently misdiagnosed. We report a diagnostically challenging case of MCL that first appeared as a nodule on the lower leg. CASE SUMMARY: An elderly female had a painless red nodule on the front of her right lower leg for six months. Positron emission tomography-computed tomography showed a soft tissue mass at the same site and increased activity in the right groin lymph nodes. Skin and lymph node biopsies, along with immunostaining, confirmed MCL. The patient began combination chemotherapy, resulting in a marked improvement of skin lesions and lymphadenopathy after two weeks. CONCLUSION: Cutaneous manifestations, though uncommon, may serve as the initial clinical presentation of MCL. Dermatologists and pathologists should maintain heightened awareness of this diagnostic possibility when evaluating persistent, atypical cutaneous nodules, particularly in elderly patients. Histopathological evaluation with complete immunophenotypic profiling is paramount for accurate diagnosis.